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Technical Report 009
Technologies and Services
Your reference in media technology and innovation
May 2010
L’Ancienne Route 17A
1218 Le Grand-Saconnex
[email protected]
All rights reserved.
EBU Technical Report 009
P2P Technologies & Services
A year in the Internet business is like a dog year, equivalent to seven years in a regular person’s life. Vint Cerf, Internet pioneer
General Glossary ................................................................................................... 9
Executive Summary ..............................................................................................15
Internet Media Distribution Technologies .........................................................22
Unicast streaming ..................................................................................... 22
IP Multicast streaming ................................................................................ 23
File Downloading....................................................................................... 24
Progressive Download ................................................................................. 24
Peer-to-Peer (P2P) .................................................................................... 25
Podcasting .............................................................................................. 26
Content Distribution Networks (CDNs) ............................................................. 26
Hybrid P2P – CDN systems ............................................................................ 28
A short history of P2P..................................................................................29
First generation P2P................................................................................... 29
Second generation P2P ............................................................................... 30
Third generation P2P.................................................................................. 31
A wealth of P2P networks and clients ..............................................................31
Freenet .................................................................................................. 33
Gnutella ................................................................................................. 34
Kazaa .................................................................................................... 35
BitTorrent............................................................................................... 36
µTorrent................................................................................................. 38
Tribler ................................................................................................... 39
P2P-enabled Adobe Flash player .................................................................... 40
P2P Business Environment ............................................................................40
Business Model and Cost Considerations ........................................................... 42
P2P Business Opportunities and Challenges ....................................................... 43
P2P Business Models ................................................................................... 43
P2P use cases ............................................................................................46
Streaming media services ............................................................................ 46
P2P-enabled Internet-format catch-up TV services .............................................. 46
P2P-enabled Internet device to record broadcast programmes................................ 46
Progressive download services ...................................................................... 47
Deferred download services ......................................................................... 47
Broadcast content related URI available from P2P-enabled Internet device ................ 47
Protected content with Portal....................................................................... 47
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Protected content without Portal ...................................................................47
PIP to display signing services........................................................................47
P2P-enabled IPTV HNED accessing CoD services ..................................................48
Broadcast subtitles to be carried by P2P ...........................................................48
P2P-enabled Internet DVR to record broadcast content .........................................48
Protected content on multiple devices.............................................................48
Picture-in-Picture (PIP) to display Internet content related to main broadcast .............48
Pre-positioned download services ...................................................................48
Customized Programming Guides....................................................................49
Broadcast Technical and Commercial Requirements for a Viable P2P System ............ 49
Motivations and objectives ...........................................................................50
Working assumptions ..................................................................................51
System architecture ...................................................................................51
General P2P-related requirements ..................................................................53
P2P delivery-related requirements..................................................................54
Social networks and user preferences ..............................................................55
Content formats ........................................................................................55
Content delivery........................................................................................55
Content acquisition ....................................................................................56
Service management and service monitoring......................................................56
Management of P2P functions in a CE device......................................................57
Security issues ..........................................................................................57
Geolocation, DRM and storage-related issues .....................................................57
Network neutrality.....................................................................................58
Existing commercial P2P services................................................................... 58
Octoshape ...............................................................................................59
RawFlow .................................................................................................59
Abacast ..................................................................................................60
BitTorrent DNA .........................................................................................61
PPlive ....................................................................................................62
SwarmPlayer ............................................................................................63
P2P Trials, Experiments and Experiences......................................................... 64
Eurovision Song Contest ...............................................................................64
EBU Member Services ..................................................................................64
EBU Test at IBC 2006 ..................................................................................65
Prix Europa 2006 concert .............................................................................66
WDR evaluations of PPLive and TVants .............................................................66
Danish Broadcasting corporation P2P trials using RawFlow and Octoshape ..................67
EBU P2P Media Portal..................................................................................69
EBU’s Tribler experiences ............................................................................70
IBC 2008 and IBC 2009 – P2P-Next trial using a Pioneer set-top-box...........................71
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P2P Social Networks....................................................................................72
Free-riding issue ....................................................................................... 72
User data and privacy issues ......................................................................... 73
Consumer Electronics ..................................................................................74
P2P-enabled Devices .................................................................................. 74
Implications of P2P for CE Devices.................................................................. 74
Motivation for CE vendors to build P2P Enabled Devices........................................ 74
Internet TV Products .................................................................................. 76
Telecom Views on P2P Distribution Systems and Services .....................................76
Business Opportunities................................................................................ 76
Challenges for Telcos ................................................................................. 77
ISP- P2P Collaboration ................................................................................ 77
Integration of P2P Client at Customer Premises Equipment.................................... 78
P2P-related Geolocation Systems ...................................................................79
Accuracy ................................................................................................ 80
Robustness .............................................................................................. 80
Security ................................................................................................. 80
Secure connection ..................................................................................... 80
Server side components .............................................................................. 80
Interoperability ........................................................................................ 80
Flexibility of coverage ................................................................................ 81
End User Access ........................................................................................ 81
P2P-related Metadata ..................................................................................81
P2P-related Digital Rights Management Systems .................................................83
Legal and Regulatory Matters pertaining to P2P .................................................84
Distinction between Scheduled versus On Demand content .................................... 84
European content...................................................................................... 85
Advertising rules ....................................................................................... 85
The (future?) role of ISPs ............................................................................. 85
Global Internet Licence............................................................................... 86
Must carry............................................................................................... 86
Net neutrality .......................................................................................... 87
Country-of-origin-of-initial-transmission........................................................... 88
Discussion on xDSL Network Asymmetricity ......................................................88
Members experiences ................................................................................. 88
Technical discussion on Asymmetry ................................................................ 89
Some conclusions on asymmetry .................................................................... 91
Trends in P2P Research and Development ........................................................92
P2P-Next ................................................................................................ 92
SmoothIT ................................................................................................ 96
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NAPA-WINE ..............................................................................................96
VICTORY .................................................................................................98
P4P ..................................................................................................... 100
Digital Video Broadcasting (DVB) Project ........................................................ 100
Use of SVC/MDC (Scalable Video Coding/Multiple Description Coding) in P2P Systems .. 102
SWOT Analysis of P2P Systems .....................................................................106
Strengths .............................................................................................. 106
Weaknesses ........................................................................................... 106
Opportunities ......................................................................................... 107
Threats................................................................................................. 107
Main Challenges and Open Questions .............................................................108
Efficiency .............................................................................................. 108
Upper bound/scalability ............................................................................ 108
Network Topology .................................................................................... 109
(De-)centralization balance ........................................................................ 109
Latency ................................................................................................ 109
Service reliability (QoS) ............................................................................. 109
Traffic Peaks .......................................................................................... 109
Critical mass of peers ............................................................................... 110
Switching time........................................................................................ 110
20.10 DSL asymmetry ....................................................................................... 110
20.11 Large bitrate (HDTV) streaming ................................................................... 110
20.12 Geolocation ........................................................................................... 110
20.13 Virus contamination ................................................................................. 110
20.14 Possible Blockage of P2P packets.................................................................. 111
Summary and Conclusions ...........................................................................111
Appendix 1: Functional and Operational Requirements for an EBU P2P System ..................117
Appendix 2: DVB requirements of P2P .....................................................................119
Internet-TV Content Delivery Architecture................................................................119
Commercial Requirements for P2P Internet-TV Content Delivery ....................................121
General requirements........................................................................................ 121
P2P Internet-TV Content Delivery Management ......................................................... 122
Auditing ........................................................................................................ 123
P2P Client management ..................................................................................... 123
Content acquisition and consumption ..................................................................... 124
Security requirements ....................................................................................... 124
User privacy ................................................................................................... 125
EBU Technical Report 009
P2P Technologies & Services
This document is written from the point-of-view of public broadcasters. It considers Peer-to-Peer
(P2P) as a legal distribution mechanism for transport/distribution/delivery of legal TV/video
content over the open Internet. In the past P2P protocol has been tainted by its association with
copyright piracy. Many detractors still associate P2P with illegal file sharing. It is now possible to
remove its bad name and consider P2P as a legal mechanism.
The present document is the result of collective work of Members of Project Group D/P2P (Peer-toPeer) between February 2006 and March 2010. During these four years the group was able to review
a large number of documents, perform some technical tests, organised several P2P demonstrations
at IBC conventions, run a major trial on EBU Media Portal and evaluate a number of commercial
propositions. The Group did not consider only technical issues but tried to address also some nontechnical matters such as operational, business, legal and regulatory. The Group produced a
number a valuable contributions to external bodies such as the DVB Consortium and the EC funded
project P2P-Next.
The Group would like to express its gratitude to the EBU management for support and
encouragement and the EBU Member organisations that were represented in the Group.
Particular thanks should go to those numerous EBU and non-EBU experts who actively contributed
to this document, in particular:
Jari Ahola (VTT, Finland)
Stephen Alstrup (Octoshape)
Anne-Catherine Berg (EBU Legal Dept.)
Thomas Buchholz (Deutsche Telekom)
Stefan Clyck (VRT)
Matthias Hammer (IRT)
Frank Hoffsümmer (SVT)
Thomas Elton Jensen (DR)
Frans de Jong (EBU Technical)
Rainer Kirchknopf (ZDF)
Christian Klöckner (WDR)
Olli Karonen (Nokia)
Peter Lanigan (Philips)
Deon Noerskov Mathiesen (Octoshape)
Michael Moelants (VRT)
Enrico Magli (Politecnico di Torino)
Johan Pouwelse (TUD Delft)
Heijo Ruijsenaars (EBU Legal Department)
Mark Stuart (Pioneer)
Rafal Wiosna (TVP)
The document was compiled by Franc Kozamernik (EBU Technical). It was proofread and edited by
Ed Wilson and Roger Miles (EBU Technical).
EBU Technical Report 009
P2P Technologies & Services
EBU Technical Report 009
P2P Technologies & Services
General Glossary
Asymmetric Digital Subscriber Line
Autonomous System (RFC 1930)
Broadband Content Guide
Content Distribution Network
Consumer Electronics
Common Intermediate Format is a video format used to standardize the horizontal and
vertical resolutions in pixels(typically 352 x 288) of YCbCr sequences in video signals.
A protocol that allows networked devices to be assigned a unique IP address
automatically from a pool of unused IP addresses.
Distributed Hash Table
Home Network Gateway
Domain Name System
Denial of Service
In a direction towards the end-user
Digital Rights Management
Digital Video Broadcasting (Consortium)
Digital Video Recorder (usually hard-disk based)
Electronic Programme Guide
EBU P2P System
Edge Side Includes: is a small markup language for edge level dynamic web content
assembly. The purpose of ESI is to tackle the problem of web infrastructure scaling
File Delivery over Unidirectional Transport
High Definition Television
Home Networked Device (DVB denomination)
Hypertext Mark-up Language
HyperText Transfer Protocol
Internet Assigned Numbers Authority
Internet Content Adaptation Protocol
Internet Group Management Protocol (RFC 3376)
Internet-TV Device
An Internet-TV Device is defined as a consumer appliance (i.e. Set-Top Box, TV set,
media-enabled PC, etc.), that is connected to the Internet via a broadband connection
(such as ADSL, cable, fibre, etc) and which uses typically a remote control. The
Internet-TV device shall be implementable with today’s chip sets for consumer digital
TV devices including storage for the P2P system.
Internet Protocol Television (managed service)
Internet Service Provider
LAN address
The private, internal IP address that locates a computer on a Local Area Network. A
LAN IP address is not visible to users outside of the LAN. As described by RFC 1918, the
following ranges are designated as reserved IP addresses for private LANs: - - -
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P2P Technologies & Services
Legal Content
Content which is distributed and acquired according to the positive legal requirements
(e.g. copyright)
Moving Picture Expert Group
This is a technique for one-to-many communication over an IP infrastructure in a
network. It is often employed for streaming media and Internet television applications.
Network Address Translation: The changing of the source or destination IP address for a
data packet. This usually occurs when one is behind a firewall or router, where it
translates IP addresses so that multiple computers can exist on a LAN with while using
the same WAN IP address.
NAT Port Mapping Protocol: An alternative to UPnP created by Apple, Inc. NAT-PMP is
not as widely supported as UPnP is, and uptake of the protocol has been limited to
Apple, Inc. products only thus far.
Open Pluggable Edge Service
P2P Flow
A logical data flow being exchanged between different elements of the P2P-InternetTV Content Delivery system
Personal Computer
"Quarter CIF" - this implies that the height and width of the CIF frame are halved.
Quality of Experience (latency, download time, etc)
Quality of Service
Really Simple Syndication is a family of web feed formats used to publish frequently
updated works such as blogs, news headlines, audio and video.
RSS feed
A file that is updated so that it delivers information and content in such a way that
allows one to track updates quickly and easily.
Remote Management System (DVB)
Real-time Transport Protocol (RFC 3267)
Real-time Streaming Protocol (RFC 2326)
Service Discovering and Selection (DVB)
Set-top box
Static IP Address
An IP address that does not change (remains static) across multiple sessions. A static IP
address is necessary in port forwarding, as ports are usually forwarded to a specific IP
address, where the rule does not change even if the computer's IP address does.
User Data Protocol (RFC 768)
This is the sending of messages to a single network destination on a packet switching
network. Unicast messaging is used for all network processes in which a private or
unique resource is requested.
A protocol that allows devices on a network to communicate with each other
seamlessly. In the case of µTorrent, UPnP is used to forward a port on a router without
the need to open the port manually.
In a direction away from the end-user.
Users’ context
Access network capability, storage capability
A computer network that covers a large geographical area. A WAN connects multiple
LANs together. The Internet is an example of a WAN.
Any type of Digital Subscriber Line, including ADSL and VDSL.
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Glossary of some specific BitTorrent related terms
The act of connecting to a tracker to update it on your status, and to obtain
information from it as well, including (but not limited to) an updated peer list.
The number of complete copies of the torrent contents that are distributed in the part
of the swarm you're connected to. The amount of the torrent contents you currently
have is included in the availability count. A swarm with no seed and with availability
below 1.0 will likely be unable to finish transferring the complete torrent contents.
The units of data that comprise a piece. Because blocks do not directly affect whether
torrent contents are considered to be finished transferring, it is not seen as an
appreciable unit of data with regards to BitTorrent like the piece is.
The act of downloading content from an RSS feed
This word describes the state of a BitTorrent connection. When a connection is choked,
it means the person who is supposed to be doing the uploading on the connection does
not want to send anything. This generally happens when the uploader's upload slots are
The application a user is using when connected to a swarm. In this case, the application
being used to connect to swarms is µTorrent, so it is the client.
Distributed hash Table: A distributed tracker that works similarly to a regular tracker in
that you announce to it and get back a list of peers that are transferring the same
.torrent file as you. Because DHT is distributed, there is no single point of failure, so
even if a single node disconnects from DHT, the tracker will continue to work (unlike
with normal trackers, where if the server goes down, it becomes unusable). DHT can be
thought of as a backup tracker.
Disk cache
A feature that makes use of available memory to stores data for quicker access as well
as ease disk thrashing. The use of a disk cache will cause an increase in memory usage
in return for improved performance.
Disk thrashing
When a storage disk gets accessed very frequently. Extended disk thrashing may lead to
hard drive wear and tear, shortening a drive's life.
Endgame mode
A change in the piece requesting strategy that occurs when a download is near
completion during which the client requests pieces from all connected peers rather
than requesting a piece from one peer at a time in the normal operating mode.
Endgame mode is used because download rates often slow down considerably as a
torrent job nears completion due to the tendency for the remaining pieces to be
downloaded from peers with saturated connections. By requesting data from all peers
rather than waiting for a single peer, such a bottleneck can be bypassed. This mode is
not used during normal operating modes because of the large amount of overhead it
potentially generates in sending requests to all peers.
Ephemeral port
A range of port numbers automatically allocated by the operating system for use by any
application on the system with network access. Ports in the ephemeral port range are
typically used to make temporary outgoing connections. By default, the ephemeral port
range is defined from ports 1024 to 5000, but this is configurable via the Windows
Registry, and may vary from (operating) system to (operating) system.
A ‘fingerprint’ of data assumed to be unique to the data. Because of the assumed
uniqueness of the data, it is used to verify that a piece of data is indeed uncorrupted
(since the corrupted data's hash would not match its expected hash).
Hash check
The comparing of a piece of data's hash with a reference hash in order to verify the
integrity of the piece of data.
A site that lists .torrent files available for download.
Initial seeding
Also super-seeding: A method of seeding that attempts to decrease the bandwidth load
for the initial seeder. With normal seeding methods, the initial seeder typically has to
upload 150% to 200%, or even more, of the original data in before a full copy of the
data has been distributed into the swarm. With initial seeding, the initial seed attempts
to get the rarest pieces out instead of uploading identical pieces repeatedly, often
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P2P Technologies & Services
lowering the initial upload requirement to 105%. Initial seeding does not necessarily
improve upload speeds or decrease seeding time. It should be used only if you are the
sole seeder on the swarm, and if there are at least 2 peers connected. Generally, initial
seeding should not be used by people with high upload speeds.
This word describes the state of a BitTorrent connection. When a peer is interested, it
means the peer is interested in the data that the peer on the other end of the
connection has, and is willing to accept data from the other peer.
Local Peer Discovery: A method by which Torrent attempts to discover new peers local
relative to your computer's network. Local Peer Discovery makes use of IP Multicast.
A person who downloads, but fails to reciprocate the generosity of others by not
sharing back. The word ‘leecher’ carries a strong negative connotation.
Micro transport
A UDP-based reliable transport protocol designed to minimize latency, but maximize
bandwidth when latency is not excessive. This alleviates the bandwidth saturation that
often occurs to BitTorrent users while they are transferring data and using the Internet
for other purposes.
Optimistic unchoke When a client tries to start a transfer on a previously choked connection in hopes that
the connection becomes unchoked.
Protocol Encryption: A specification designed jointly by Vuze and µTorrent developers,
created as an attempt to bypass throttling and/or blocking of BitTorrent traffic by ISPs.
There are different methods of encryption, ranging from full encryption of all of the
data, to partial encryption (header encryption only, not unlike with PHE, although it is
still not as easily detected as PHE).
Peer Exchange: A feature to exchange peer lists with other peers that support the same
PEX implementation (generally limited to peers using the same BitTorrent client). By
exchanging peer lists, it's possible to find peers not included in the peer list supplied by
the tracker.
Protocol header Encryption: An old method of encryption created by the BitComet
developer that encrypted only a part of the data (the header) in an attempt to bypass
ISP throttling and/or blocking of BitTorrent traffic. Because its specification was
designed in a relatively poor manner, ISPs were able to detect it with little trouble,
rendering it useless.
The smallest appreciable unit of data in BitTorrent. The size of pieces can be different
depending on the .torrent file in question.
Piece distribution
The general distribution of the pieces across the swarm. BitTorrent is generally most
efficient when piece distribution is random, with minimal ‘clumping’ of pieces
available in the swarm.
The act of intentionally feeding invalid data into the swarm, resulting in hashfails for
peers receiving the invalid data. Outfits with (or hired by other entities with) anti-P2P
agendas are the most common sources of swarm poisoning.
Port forwarding
The act of passing data on the forwarded port from one network device to another. In
most cases regarding BitTorrent, port forwarding refers to the forwarding of
connections from a router to a specific computer attempting to listen on that port.
Private flag
A piece of information stored in a .torrent file that tells any BitTorrent client that
recognizes the flag to disable DHT, LPD, and PEX for that specific .torrent. The 'private'
flag is typically used in .torrent files served by private trackers as a method of keeping
a swarm isolated from people who aren't members of the private tracker.
Private tracker
A tracker that requires users to log in to use it. Private trackers typically enforce ratio
requirements (by banning users whose ratios are too low) in order to prevent or
minimize the leeching that is prevalent on many public trackers.
Public tracker
A tracker that is open for anyone to use (as opposed to private trackers, where only
people who hold accounts can use the tracker).
The grabbing of statistics (number of seeds and peers) from a tracker regarding a
specific swarm.
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A peer with 100% of the data in the torrent contents.
The act of being connected to a swarm as a seed.
This word describes the state of a BitTorrent connection. A connection is marked as
snubbed when the client has not received anything over the connection for an extended
period of time.
The collective group of peers (which include seeds) that are connected by a common
.torrent file.
A term used to refer to the intentional slowing down of transfer rates (download and/or
upload), typically used in the context of ISP throttling.
A small file containing metadata from the files it is describing. In other contexts, it is
sometimes used to refer to the swarm connected around that small file.
Something that a client connects to in order to share its IP and port, as well as obtain
information, including peer lists.
The act of transferring data from your computer onto another.
Data that is tossed out either because it hashfailed, or because it was redundant data
that the client had already downloaded.
Web seed
A seed that is basically a regular web server hosting the requested file. BitTorrent
clients that support web seeds use them like any other seed, and can request data
segments from the server much like requesting pieces from an ordinary seed. The use
of web seeds ensures that a torrent swarm will never die as long as the file being
seeded is left intact on the server and the server does not go down.
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EBU Technical Report 009
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Peer-to-Peer (P2P) Technologies and Services
Keywords: P2P, Peer-to-Peer, Internet Radio, Internet TV.
Executive Summary
This document summarizes the studies carried out by EBU Project Group D/P2P (Peer-to-Peer). The
Group was tasked to investigate the new Internet-based media delivery mechanism based on gridtype (distributed) technologies and assess its suitability for broadcasters to distribute large-scale
high-quality audio-visual streams and files to the general public in a cost efficient, reliable, and
user-friendly manner.
Background: The EBU’s involvement in P2P goes back to February 2006 when the EBU organised a
workshop ‘From P2P to broadcasting’. This event was held at a time when more and more
broadcasters were just starting to use regularly the Internet to distribute their live or on-demand
programmes. At that time, P2P technology was still largely associated with illegal file sharing and
tainted by its association with copyright piracy as a result of the illegal activities of Napster, Kazaa,
Glockster, etc. The usage of Internet was exceedingly expensive for broadcasters, as they were
charged by Internet Service Providers (ISPs) for each delivered stream (in gigabytes). Broadcasters
therefore became victims of their own success: The more popular their content, the more they
needed to pay for the distribution of their content. The situation became increasingly untenable.
The EBU workshop was a big success, with more than 100 participants, including representatives
from more than 30 TV & Radio EBU Members and associate Member organisations. This landmark
event showed that P2P could actually become a useful technical solution, potentially more cost
efficient and robust than any other traditional Internet distribution method. The EBU members
showed a significant interest in studying P2P technologies and were prepared to run experiments
and trials in order to gain practical experience. Members felt it necessary to improve the public
image of P2P and consider P2P a legal mechanism for the transport and distribution of legal
TV/radio content. The workshop helped broadcasters to better understand what potential impact
P2P could have on business, revenue, and distribution models.
EBU Project group D/P2P: As a result of this workshop, the EBU Delivery Management Committee
(DMC) set up the D/P2P Project Group which held an exploratory meeting in April 2006. In the three
years of its existence, the group held nine meetings, the last one on 6 and 7 May 2009 in Geneva.
The Group counted as many as 96 members from all constituencies: public and commercial
broadcasters, telecoms, ISPs, CDNs, P2P operators, technology providers, manufacturers, chip
developers, universities, and legal experts. The group worked very closely with EC-funded projects
and universities and contributed towards standardisation within DVB. In the course of its existence,
it examined almost 150 input documents. The Group organised a real-life trial of EBU P2P media
portal involving several EBU TV and radio stations. The Group provided support to the EBU’s
Eurovision Song Contest.
Document structure: This document is a comprehensive report on P2P, as seen by the EBU
members. The first four chapters provide a tutorial on P2P technology and positions P2P amidst
other distribution technologies such as Unicast, server-based content distribution networks, IP
Multicasting and others.
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Chapter 5 describes the P2P business environment and provides some P2P business models and cost
considerations. The P2P services can be provided by content providers, service providers, or by
special entities, P2P service providers. The latter ones play the same role as conventional CDN
(Content Distribution Network) providers.
Chapter 6 offers some typical possible P2P use cases. These use cases are given as examples of
possible usages and do not imply that P2P is the only possible technical solution for a given task –
other solutions may also be used (and may often be even more efficient than P2P).
Chapter 7 is a key part of the report – it gives the technical and commercial requirements for a
viable P2P system from a broadcast perspective. These requirements were submitted to the DVB
Project and will represent a basis for a future P2P standard.
Chapter 8 provides a brief review of some existing commercial P2P services and systems that have
been successfully deployed in the Internet market. These systems are all proprietary and are not
interoperable. EBU members have evaluated many of them.
Chapter 9 is a collection of P2P trials, experiments, and experiences in which the Group (or its
members) was involved. The experience running the EBU P2P Media portal available from the EBU
web site is also described.
Chapter 10 describes P2P social networks in which peers share common activities, for instance
exchange audio files, chat, socialise, etc. Social networks are an important mechanism for building
communities around broadcast TV programmes. They may represent a way to attract new,
particularly younger, audiences.
Chapters 11 and 12 were prepared by the manufacturer and telecom members of the group,
respectively. These chapters significantly enrich the document by including some views and
opinions from non-broadcasters. In many ways they provide a somewhat critical account of P2P.
Chapters 13, 14 15 and 16 address some ancillary topics, that are not linked directly to P2P
technology but are important for P2P operations: geolocation, metadata, digital rights management
(DRM), and the legal requirements. Geo-filtering and DRM may be important for copyrighted
materials and premium services. It is recognised that neither DRM nor geo-filtering are able to
ensure absolute security and protection, and can be hacked if sufficient effort is made.
Nevertheless, they are seen by many broadcasters and content providers as indispensible ‘best
effort’ protective measures that need to be applied. Metadata describe the content conveyed via
P2P and the context in which the content is generated, transported and used.
Chapter 17 discusses the limitations of P2P networks if users utilise asymmetric lines with limited
upstream capacity. The asymmetry of DSL lines is often a critical limiting factor determining the
efficiency of the P2P system. The chapter gives some quantitative analysis of the problem and
makes an estimate of how much capacity should be provided by a central server (in comparison to
the capacity provided by peers).
Chapter 18 looks into the future: what are the future trends in P2P research and development. It is
evident that P2P is a novel technology with a huge potential for future developments and
refinements. This chapter lists the main projects involved in P2P R&D and how P2P will improve
further in terms of its efficiency, robustness, availability and user friendliness. The fact that so
many R&D projects are involved in P2P highlights the interest for this technology. It may be useful
to single out a particular aspect: a conjunction of P2P with scalable video coding (SVC or MDC)
enabling an adaptive P2P system. Developing network topology aware P2P systems is another
interesting research topic.
Chapter 19 contains the SWOT analysis, which outlines the P2P system’s strengths, weaknesses,
opportunities and threats, as perceived by broadcasters.
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Chapter 20, ‘Main challenges and open questions’, discusses the remaining issues that may still
require further studies and careful considerations, should P2P become a viable distribution system
to be used for broadcast purposes.
Key messages: Also to be found in Chapter 20. They can be summarised as follows:
‘P2P is an attractive novel technology, which may potentially revolutionize the business of media
distribution over the open Internet. P2P technologies are still being developed and refined and
will definitely find their place in the media distribution landscape. P2P is highly disruptive but is
likely to bring distribution costs down. Indeed, it has already brought the prices down by an order
of magnitude. In order to exploit full potential of P2P, broadcasters need an open, standardised,
license-free P2P solution that could be embedded in the range of consumer-electronic devices. It
should be pointed out that P2P technologies will not replace conventional terrestrial, satellite and
cable broadcast networks. For Internet distribution the trend now is to use a combination of
centralised (e.g. CDN) and decentralised (e.g. P2P) approaches.’
This report addresses some particular issues related to P2P distribution of media over the Internet,
Internet distribution costs: P2P is able to reduce significantly the server cost, bandwidth,
and network load. Practically every individual user can now become a ‘broadcaster’. The
use of open source BitTorrent server by NRK and the BBC is an example of how broadcasters
can reach the general public with their content almost for free.
Cost incurred by the user: There is also a question of cost incurred by the user. The
dominant view of the D/P2P group is that most people would be ready to pay for better
quality. A business concept of tiered services may be one way forward. For example, users
may be prepared to pay for high-quality services, whereas normal, baseline webcasts at,
say, 350 kbit/s, would be for free.
New business models: P2P has been instrumental in introducing new flexible business
models for the end users, technology and service providers.
Social networks: A P2P system can be regarded as a social network of ‘friends’ sharing the
same interests and tastes – P2P may thus have an important social, community impact. This
aspect should not be neglected, as broadcasters endeavour to build stronger links to their
viewers and listeners.
Short and long tails: P2P is particularly a suitable solution for distributing very popular
content, as a large number of peers can participate in serving the content to other peers.
However, P2P is also suitable to distribute ‘long tail’ content. Broadcasters may use it to
target niche audiences. Such a P2P solution is undoubtedly cheaper than setting up new
terrestrial broadcast networks to cover a few viewers and listeners. P2P delivery can
potentially save significant amounts of broadcasting spectrum which is a very scarce
Audience measuring: One important advantage of the Internet is the possibility to measure
audiences very accurately and not merely estimating them by using limited audience
samples. This may radically impact the business models including personalised advertising
used in the open Internet.
P2P embedded devices: In 2008, Octoshape released an announcement that it launched in
association with an American company CaptiveWorks a commercial P2P-enabled set-top
box1. This product, along with the DVB efforts to standardise P2P-enabled Internet TV
consumer electronic devices, may establish the Internet as one of the principal delivery
Pioneer successfully demonstrated a TV STB using the Tribler P2P client at IBC 2008. This development was performed
within the framework of the P2P-Next project. An improved version of the Pioneer STB was shown at IBC 2009
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mechanisms of broadcast-quality television signals to the hybrid broadcast/broadband settop box and integrated digital TV. DVB has launched a Study Mission in order to establish
whether or not P2P compares favourably to other Internet distribution mechanisms.
Upload contribution of ‘passive’ peers: It should be pointed out that P2P is not a panacea.
This report provides a critical assessment of P2P weaknesses and identifies numerous open
issues. There may be circumstances where P2P solutions may be less than optimal.
Typically, such a case may occur in the countries where Internet consumption is limited to a
certain amount of download and upload capacity. The concept of ‘passive contributions’
provided by stand-by peers to increase overall network upload capacity would help in such
Centralisation: One open question is whether the P2P system could be totally decentralised.
The view of the Group is that content and network security could be better administered
and controlled if a limited central network element managed by a content or service
provider would be used.
Quality of service: Some effort should be made to improve QoS (Quality of Service) and QoE
(Quality of Experience) of Internet TV services. This report does not address the technically
solutions to improve the all-important QoS-related issues, such as latency, channel-change
time, buffering, resilience to packet losses and jitter, service availability, ability to cope
with flash crowds, etc . Nevertheless, these issues will have to be addressed by an
appropriate technical body, e.g. DVB.
Net neutrality: The question of ‘net neutrality’ is still pending. This matter is highly
political and should be resolved at the highest political level in Europe. It is clear that very
tight rules will be required in order to prevent ISPs from shaping and filtering Internet
(including P2P) traffic. Such traffic shaping may be potentially detrimental to broadcast
content distribution. The distribution of professional broadcast content should not be
adversely affected by any inappropriate ISPs activities.
Synergy of CDN and P2P: The final observation is that P2P may be used as an add-on to
conventional CDNs; rather than increasing the number of edge servers, one can use P2P to
bring the signal to the general user through the existing infrastructure consisting of end-user
devices (PCs, STBs, game consoles, mobile devices, etc).
It is recommended that EBU members continue considering P2P as one possible choice for
distributing audio/video/data over the Internet. Members are encouraged to continue gathering
operational experience by running P2P-driven services and sharing i he results with other Members.
The future is uncertain and it is not possible to predict whether or not P2P will ultimately be
successful in the media distribution market. The degree of success will probably vary across
different European markets and will heavily depend on the regulatory arrangements adopted in the
countries concerned. However, a significant impetus for the promotion of P2P may occur with the
advent of large-scale affordable commercially-available P2P-enabled televisions and STBs.
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The Internet was designed to provide relatively short duration connections for delivery of web
pages. It was never designed to carry huge video files and deliver them to a large number
(potentially counting several millions) of concurrent users. It is relatively easy to carry a web page
(some tens of kbyte), it is totally another matter to deliver a film which is equivalent to 100000
web pages (several Gbyte) [1]. If a web page fails to load properly, you click the refresh button and
fix the problem easily. For video, however, long duration connections lasting several hours may be
required. Clicking the refresh button in the middle of a film would re-start a film, and this would
be a major inconvenience. Video delivery also requires larger and more consistent network
bandwidth availability.
Today, the broadband Internet has become a consumer utility akin to the electrical power supply.
More, it has become a useful complement to the traditional distribution channels of radio and
television programmes, such as satellite, cable, terrestrial networks. During the forthcoming years,
the Internet is likely to become a major means to bring radio, television and multimedia to the
home and to users on the move2. Both back-bone Internet connections and access links to the home
are getting faster and faster. Availability and deployment of broadband access is rapidly expanding
worldwide. The ability of the network to provide reliability and low latency is improving and the
cost of transmission is decreasing.
The key question is whether the Internet will be able to cope with the ever increasing traffic
volumes or not. The major increase of traffic is due to all kinds of video content: live broadcasts,
movies-on-demand, catch-up TV and user-generated content. Having initially accepted lowresolution small-screen video, the public now expects standard or even high-definition (HD)
television quality content without buffering and delay. Better quality of digital media drives
audiences and their viewing times constantly up. The growth in Internet media consumption
presents significant economic and business challenges for content and network service providers.
Compared to other distribution mechanisms, the Internet still lags behind in terms of quality of
service, scalability and cost [2]. The Internet channel generally is characterized by long latency,
jitter and packet loss. This results in the need to provide retransmissions and long buffers at the
player end. Internet can only provide a ‘best effort’ quality unless special provisions are taken.
Furthermore, in order to reach a lot of members of the audience, it is often necessary to limit
video resolution to QCIF or CIF. Also, Internet servers can often accommodate only a small number
of simultaneous users. Scaling to large audiences is expensive for content providers and
broadcasters, as they are charged by the Internet services providers (ISPs) per each stream.
This scaling problem means that today's Internet is a very costly medium. The more users there are,
the higher the cost. Broadcasters are then penalized if their content is very popular, as they will
have to pay more for distribution. The Internet business models are not yet clear and vary from
country to country.
For Internet to become a successful medium, broadcasters need a reliable service delivery (e.g. no
glitches, no interruptions, acceptably short delay, zapping time), high intrinsic quality (e.g. HDTV,
multichannel audio, extensive metadata), scalability (large number - several millions - of
concurrent users) and low transmission cost (ideally, cost should be independent of location, time,
quality and number of users). Internet TV streaming and video downloading using the traditional
server-client distribution mechanism is now well in place and a large number of commercial
services are already deployed worldwide. Streaming traffic is among the fastest growing traffic on
the Internet. In a recent white paper, Cisco predicts that by 2012, 90% of all Internet traffic will be
The BBC iPlayer generated 94m views in December 2009. About 4m connected TVs are expected in UK homes by the end
of 2010.
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video. Compared to server-client distribution, using a peer-to-peer (P2P) distribution for
downloading and particularly live streaming is becoming mature, however numerous technical,
operational and legal challenges still need to be addressed.
There are two basic architectures for delivering streaming traffic on the global Internet: the clientserver paradigm and the peer to peer (P2P) paradigm. A particular advantage of the P2P paradigm
over the client-server paradigm is its scalability. As an example, PPLive, one of the largest P2P
streaming vendors, was able to distribute large-scale, live streaming programmes such as the CCTV
Spring Festival Gala to more than 2 million users with only a handful of servers. CNN reported that
P2P streaming by Octoshape played a major role in its distribution of the historical inauguration
address of President Obama. It is well demonstrated in practice that P2P streaming can deliver
videos encoded at a rate of about 700 kbit/s, in the presence of rapid user joins/leaves, with
positive user experiences.
P2P streaming is seeing rapid deployment. Large P2P streaming applications, such as PPLive,
PPstream and UUSee, each has a user base exceeding 100 millions. P2P streaming traffic is
becoming a major type of Internet traffic in some Internet networks. For example, according to the
statistics of a major Chinese ISP, the traffic generated by P2P streaming applications exceeded 50%
of the total backbone traffic during peak time in 2008. There were reports that major video
distributors such as YouTube and Tudou are conducting trials of using P2P streaming as a
component of their delivery infrastructures. Given the increasing integration of P2P streaming into
the global content delivery infrastructure, the lacking of an open, standard P2P streaming protocol
becomes a major missing component in the Internet protocol stack. Multiple, similar but
proprietary P2P streaming protocols result in repetitious development efforts and lock-in effects.
More importantly, this leads to substantial difficulties when integrating P2P streaming as an
integral component of a global content delivery infrastructure. For example, proprietary P2P
streaming protocols do not integrate well with existing cache and other edge infrastructures.
In the Internet traffic race, P2P enjoys mixed fortunes. For years, P2P traffic eclipsed HTTP traffic
as broadband users slurped down music and movies. In June 2007, however, Ellacoya Networks
reported that HTTP traffic accounts for 46 percent of all broadband traffic in North America,
whereas P2P applications account only for 37 percent. The surge in HTTP traffic was largely due to
huge popularity of YouTube HTTP video streaming services.
Broadcasters may wish to use P2P because it scales well to provide services to a large number of
concurrent peers [3]. The server investment and maintenance cost as well as the server bandwidth
required are much lower than with other content distribution mechanisms. Consequently, P2P may
be more affordable and cost-effective than alternative content distribution systems. As the P2P
systems are generally geographically distributed across the Internet, there is no single point of
service failure. Therefore, P2P may ensure a reliable user service experience.
Nevertheless, broadcasters need to evaluate all pros and cons for P2P, investigate which P2P
solutions are best suited for the applications required and how best to integrate the P2P solutions
chosen with the traditional content delivery systems already in use.
These are the objectives of this EBU document.
The following extract from an article published in the Economist on 4 March 2010 (see box below)
provides an excellent introduction to explaining the reasons why public broadcasters are interested
in experimenting with P2P technology.
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Video on the Internet: Why are public broadcasters experimenting
with the ‘peer-to-peer’ technology beloved of online pirates?
Last year Norway’s public broadcaster, NRK, filmed a stunning seven-hour train ride between Bergen and Oslo, shot
entirely in high-definition video. Over one million Norwegians watched the film on television. But NRK faced a challenge
in reaching a larger audience. How could it distribute the hard-drive-busting 246 gigabytes of raw footage to a global
audience without bringing its servers to a grinding halt? The broadcaster made a somewhat surprising choice: it turned to
BitTorrent, a peer-to-peer (P2P) Internet service best known as a means of sharing pirated movies and music.
Some at NRK worried that using a system associated with piracy would generate negative publicity. But BitTorrent itself is
value neutral. It is a uniquely efficient distribution method that lets broadcasters ‘seed’ the Internet with one or two
copies of their massive media files. It then relies on end users (called peers) who request the file and receive different
pieces of it. To assemble a complete version of the file, these peers then share their pieces with each other (hence ‘peer
to peer’). It takes a while, but the broadcaster does not need expensive server farms or fat data pipes to deliver massive
files to viewers anywhere in the world.
Several other public-service broadcasters have also been experimenting with P2P distribution, probably because they are
relatively insulated from commercial pressures. In 2008, for instance, Canada’s CBC used BitTorrent to distribute a high
quality, unprotected version of a prime-time reality show called ‘Canada’s Next Great Prime Minister’.
The British experience, however, reveals that P2P distribution is no panacea. When the BBC rolled out iPlayer, its
television catch-up service, in 2007, it initially relied on P2P techniques to offload the burden of supplying so many large
files. At the time, the BBC’s Anthony Rose believed that P2P was the only way to provide the service. Yet one year later,
the BBC had switched to streaming content directly from its own servers. The reason? A 90% drop in the cost of
There were other problems with P2P. Many users did not realize that they had become video distributors by installing
iPlayer, and complained about slower computers and upload speeds, or about exceeding a monthly data cap. From an
ease-of-use standpoint, there is another drawback: most P2P systems work only with complete downloads, not with
streaming video of the kind on YouTube. And if there is one thing that unites Internet users, it is impatience: multi-hour
waits to download an episode of ‘Top Gear’ are intolerable.
None of this has stopped the European Union from investing in P2P as a route to the remaking of broadcasting. In 2008 it
put €14m of funding into a four-year project called P2P-Next. It is an ambitious international undertaking backed by
research institutes, companies and some broadcasters, including the BBC.
Television sets are already starting to stream Internet video from companies like Netflix in America. If P2P-Next has its
way, televisions, computers and mobile phones will all support a standardized P2P network for streaming content
distribution in the future. The idea is to create the world’s best video service: from anywhere on earth, users can then
use a standard protocol to pull up any video, at any time and on any screen.
Despite the hitches, P2P may yet be the right way to do this. Bandwidth may be cheap now, but many worry that the
explosive growth of video, much of it in high-definition formats, could soon clog up the Internet. Traffic from legal online
video sites like Hulu, iPlayer and YouTube has surged in recent years, increasing from 13% of all Internet traffic in 2008 to
27% in 2009. Furthermore, the current infrastructure of the Internet is not suited to the simultaneous transmission of live
events to millions of viewers.
Johan Pouwelse, P2P-Next’s scientific director, imagines a brave new world for broadcasters in which interconnected
television sets with P2P sharing can give any television station global reach. Barriers to market entry will be low, ensuring
healthy market competition, he says. ‘Satellite gave us hundreds of channels—Internet television can give us all the freeto-air channels of the globe.’
The business model that will support all this, however, is not yet clear. Advertising, the lifeblood of many broadcasters,
is difficult to do globally. And distribution through P2P networks has costs. Many broadcasters make a great deal of money
by selling international distribution rights. Though there may be little commercial demand for a seven-hour documentary
of a train journey in Norway, and so no harm done by giving it away, the BBC makes lots of money selling programmes
such as ‘Top Gear’. It is unlikely that broadcasters, even in the public sector, would give away for nothing on the Internet
what they might otherwise sell through traditional routes. Until a better reason for using P2P distribution emerges, it may
only be of niche interest to the big broadcasters.
Courtesy of the Economist, 4 March 2010
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Internet Media Distribution Technologies
This section provides high-level background information to the following Internet media delivery
IP Multicast streaming
File Downloading
Progressive Download
Peer-to-Peer (P2P)
Content Distribution Networks (CDN) and
Hybrid P2P-CDN systems.
Unicast streaming
Unicast describes a point-to-point network communication used for sending information packets
individually from a server to a client. Server and client are identified by their individual IP address
assigned at least for the duration of the communication session. For each additional client,
requesting the same content, a new Unicast connection has to be established, requiring:
a distinct copy of the information packets,
establishing a connection on the IP layer,
encapsulation of the information packet into a transport protocol and
a broadband connection to the Internet (except for audio only applications).
The transfer of a separate copy of the content to each user leads to a massive multiplication of
data transfer and a linear relation between cost and audience size.
Unicast streaming uses the Unicast protocol to transmit a continuous stream of data to a client,
an adjustment of data volume to the channel - especially the downstream data rate of the
client - by using audio and video codecs,
use of flow control and optional error correction, either using TCP (as in HTTP streaming) or
by streaming specific protocols on top of the UDP layer for example RTP/RTSP or proprietary
the client to get information about the offer and especially the address of the streamingserver,
the client to decode the stream using buffering, the selected codecs and a player to render
and display video and/or audio.
As a result of potentially huge number of users typical for TV audience, a reliable and highperformance infrastructure has to be provided by the service provider (e.g. broadcast station),
consisting mainly of streaming-servers and bandwidth. Due to the single point of failure, content
delivery networks are used often, replicating the streams in different network segments providing
redundancy. The use of content delivery networks also can provide economic and performance
benefits, the latter by temporal and regional dispersion of traffic peaks.
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IP Multicast streaming
IP Multicast represents a point-to-multipoint network communication used for sending information
packets from one source to a defined group of receivers (hosts). Network routers are responsible
for optimizing the paths between the source to the receivers and for replicating the traffic at
appropriate points within the network. Because the source only needs to send each packet once,
and it can be received by an arbitrary number of recipients, it has significant scaling advantages
compared to Unicast streaming.
While Multicast would be the distribution mechanism of choice for broadcasters, today it works
only in few network segments and autonomous systems (AS). Though inter-domain routing protocols
exist and most Internet exchange points and routers are Multicast enabled, Multicast use in the
Internet is not wide, due to the following reasons:
around the year 2000, Telcos invested huge amounts for their Internet structure. As the
Multicast protocols prevalent at the time had some problems, providers of content delivery
networks opted for using caching solutions such as Akamai CDN (Content Distribution
peering at no charge of Tier-1-providers among each other versus paid-up IP transit for Tier2 providers is a permanent political and financial issue between Telcos, and Multicast traffic
complicates the discussion further,
ISPs are primarily interested in an efficient distribution in their AS and not necessarily in the
whole Internet. To this end, large Telcos (like Telefonica and Deutsche Telecom) apply
Multicast within their network but not to other domains.
In recent years the introduction of intra-domain Multicast within the networks of ISPs has increased
as a result of the IPTV Triple Play service requirements.
The Multicast-enabled routers replicate the packets at OSI-layer 3. For every Multicast
communication there must be
one source IP address which is abbreviated (S) for the sender and
one group address as destination abbreviated (G) within the IPv4 range of and,
Both addresses are combined in the expression (S,G). Multicast packets are forwarded by a router
to other routers on the way to receivers. The router knows the hosts within its subnet by a
membership list. The membership list is defined by the Internet Group Management Protocol
(IGMP), which exists in 3 versions. The actual IGMPv3 is defined by RFC 3376 and is backwards
compatible. IGMPv3 administrates a Membership-Query using the methods General-Query, GroupSpecific Query and Group-and-Source-Specific-Query. Receivers inform the router about their wish
to participate in or to leave a group and the router stores this source filtering data in its
While Unicast routing is concerned about where the packet is going, Multicast routing is concerned
about where the packet comes from. In order to achieve an efficient routing of the content to
specially distributed receivers, so-called distribution trees are constructed, as Multicast paths to
many receivers form a tree-topology. Possible methods are Spanning Tree, Source Trees and Shared
Trees. The two latter are more flexible and thus preferred. The forwarding mechanism is based on
routing protocols defining rules for forwarding and discarding Multicast packets. Thereby they
enable routers to build a delivery tree between the sender(s) and receivers of a Multicast group.
Within domains the Routing Protocol, called Protocol Independent Multicast (PIM) is mostly used in
its Sparse Mode (PIM-SM) version. PIM-SM performs the following functions:
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builds and tears down distribution trees,
requires an explicit join-message of a router willing to participate and
uses externally-provided reachability table to build forwarding topology.
The central router within a PIM-SM is the Rendezvous Point (RP). A host joins a group by asking his
router (First-Hop-Router) who in turn registers at the RP. The further development of PIM-SM is
called PIM-Source Specific Multicast (PIM-SSM) defined in RFC 3569. PIM-SSM directly initiates a
Source-Specific Multicast distribution tree to find the shortest path and does not necessitate an RP.
Source Specific Multicast thus is based on PIM-SSM and IGMPv3 and represents the Multicast stateof-the-art. The Internet Assigned Numbers Authority (IANA) has reserved the IP Address range for SSM.
Implications within the OSI reference model that must be paid attention to are:
Layer 2: the Multicast IP address range with 28 bits cannot be mapped unambiguously to
Ethernet Multicast addresses containing just 23 bits,
Layer 4: only UDP is supported.
Additionally, practical problems exist regarding insufficient Multicast support of inexpensive routers
in the home network environment. There are open issues with wireless (WiFi) Multicast networks.
File Downloading
File transfer between hosts is the oldest form of computer networking. It accounts for the majority
of traffic in today's Internet. As an application it is characterized by the ability of the recipient to
consume the content multiple times, make copies and re-distribute. From a protocol viewpoint it
can be implemented in many different ways, from traditional FTP and HTTP download, through first
generation Peer-to-Peer protocols such as Napster, to the current leading technology of swarming
protocols such as BitTorrent.
Multicast file transfer protocols also exist, e.g. File Delivery over Unidirectional Transport (FLUTE)3,
but are not widely deployed, for the same reasons that limit the use of Multicast in general.
Progressive Download
Progressive download is a simple (HTTP) file download using a standard web server. The media
play-out starts immediately after enough data is stored (buffering) in the local RAM. Because the
media file stays in the cache memory or other local storage space, it makes trick mode like pause,
rewind or forward fast and easy to implement. Progressive download needs no large bandwidth. A
slower download capacity will simply result in a longer time before the media file starts to play.
The biggest advantage of progressive download is cost efficiency. Progressive download uses no
special streaming server and fits well in the existing Internet content delivery network. The
downside of progressive download is poor scalability.
A new development called Adaptive HTTP Streaming is being considered by several companies
including Microsoft (Smooth Streaming), Adobe, Apple and Move Networks. This system acts like
streaming but is based on HTTP progressive download. It consists of a long series of very small
progressive downloads. Adaptive HTTP Streaming has arguably become a fierce competitor to P2P.
See RFC 3926
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It has already received a prospect of significant commercial success, due to the following low-entry
barrier features:
Compatibility with existing HTTP network infrastructure such as CDNs
No firewall, NAT, RTSP interoperability issues
Smoothly adjusts the content quality to the changing network conditions and the device
processing power
The client does not need to download more than it actually consumes
Fast start up – starts with low quality and increasing quality, as buffer fills up
Provides better quality, as it uses the whole available bandwidth
A non-adaptive streaming system forces the client to select a fixed bit rate which is below
the available bandwidth; this is not the case with the adaptive HTTP streaming system.
The Adaptive HTTP Streaming system is in the process of being standardised within the Open IPTV
Forum (OIPF). Currently, OIPF works on choosing the most suitable format of segments (e.g.
MPEG-2 Transport Stream or MP4-F) and defining a client manifest.
Peer-to-Peer (P2P)
P2P systems have demonstrated their ability to provide large-scale content distribution in the
Internet. The R&D work has now moved on from file sharing to multimedia streaming of live
content such as live TV over P2P networks (P2P IPTV). There are already numbers of P2P IPTV
applications deployed on the Internet, inspired by the P2P architecture of BitTorrent or eDonkey.
Unlike a client-server based system, peers bring with them serving capacity. Therefore, as the
demand of a P2P system grows, the capacity of the network grows too. This enables a P2P
application to be cheap and scalable.
In a P2P network, the peers organise themselves into networks consisting of transient users (peers
join and leave the network at any time). Peers upload files to other peers and download files from
them. Thus, every client is a potential server (and vice versa). Since the nodes that participate in
P2P networks also devote some computing resources, such systems scale with the number of peers
in terms of hardware, bandwidth and disk space. As additional peers join a P2P network, they add
to the download and upload capacity of the system.
Today, there are many P2P networks available in the market, each with their corresponding
protocols. The protocols have the task to locate content and route query requests and query
responses. All P2P protocols share the following three steps:
Locate the content by issuing a search
Based on responses received, choose peers from which content is downloaded
Issue download requests and receive the response when download is completed.
In the peer-to-peer world there are different categorizations of P2P that range from completely
centralised to completely decentralized. In the former camp are Napster and [email protected], which
are centralised, and in the other camp, Freenet and Gnutella, which are decentralised. Napster
incorporates a centralised indexing server that knows which files are on which clients; all clients
send searches to this indexing server for locating resources. Freenet and Gnutella distribute the
database of shared resources across the clients on the network, removing any need for a central
Gnutella uses a decentralised searching and downloading algorithm. An overlay of the various peers
is dynamically constructed and queries are distributed (flooded) over portions of the overlay by
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neighbours forwarding the queries up to a certain radius. This leads to a linear growth of the load
on the node as the number of queries increase, thus Gnutella does not scale well. To handle the
scaling problem, distributed hash tables (DHT) have been proposed. The DTHs ease the query
routing problem by organising the peers in a structured overlay. Due to P2P nodes joining and
leaving the network, the hash data structure needs to be updated regularly. Some P2P systems (like
Kazaa) rely on ‘supernodes’ that retain information about the data in the peers, and all queries are
sent to them.
Podcasting is a variety of file download. It is typically (but not exclusively) intended for
transferring the downloaded files to portable media players.
Podcasting allows the Internet audience to automatically receive the latest episode of a chosen
programme as soon as it becomes available. One needs to subscribe to receive a podcast service,
rather like one might subscribe to a magazine and get it delivered each week. The receiver’s
computer will periodically poll the set of subscriptions and automatically download all new
content. The content may be automatically copied to the portable media device by the same
application responsible for downloading the content.
Subscription uses the RSS (Really Simple Syndication) protocol whereas download may use any
suitable file transfer protocol including P2P protocols. Some ‘Podcatcher’ software packages (e.g.
Miro, Juice) accept RSS-Feeds containing Torrent Enclosures. This is also known as ‘Torrentcasting’,
but it should be mentioned that these feeds are not compliant to the official definition of Podcasts.
There is also the option to add the RSS functionality to BitTorrent Clients (e.g. µTorrent and Vuze).
Websites such as offer several torrents, which can be subscribed to using RSS.
Figure 1: BT-Client µTorrent v1.8 downloading ‘The daily Buzz HD...’ announced by RSS
Content Distribution Networks (CDNs)
The Internet seems to be going through a similar phase of network evolution as the national
television broadcast networks that were built out in the 1950s and 1960s. Regional broadcast
transmitters were built in close proximity to viewers’ homes to ensure they received high-quality
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TV reception [4]. Today, many network service providers are building a new infrastructure of
caching servers located at the edge of the service area. These networks are called Content
Distribution Networks and their aim is to bring content closer to the end users.
A content distribution network (CDN) is a system of computers networked together across the
Internet that cooperate transparently to deliver content to end users, most often for the purpose of
improving performance, scalability, and cost-efficiency. The capacity sum of strategically placed
servers can be higher than the network backbone capacity. This can result in an impressive increase
in the number of concurrent users. For instance, when there is a 10 Gbit/s network backbone and
100 Gbit/s central server capacity, only 10 Gbit/s can be delivered. But when 10 servers are moved
to 10 edge locations, total capacity can be 10*10 Gbit/s.
Strategically placed edge servers decrease the load on interconnects, public peers, private peers
and backbones, freeing up capacity and lowering delivery costs. Instead of loading all traffic onto a
backbone or peer link, a CDN can offload these by redirecting traffic to edge servers.
Since edge servers are usually placed near end users, assets are delivered via fewer hops, resulting
in lower latency and increased delivery speed. End users will likely experience less jitter, fewer
network peaks and surges, and improved stream quality - especially in remote areas. The increased
reliability allows a CDN operator to deliver HD quality content with high QoS, low costs and low
network load.
Modern CDNs can dynamically distribute assets to strategically placed redundant core fallback- and
edge-servers. They can have automatic server availability sensing with instant user redirection. A
CDN can offer 100% availability, even with large power, network or hardware outages.
Modern CDN technologies give more control of asset delivery and network load. They can optimize
capacity per customer, provide views of real-time load and statistics, reveal which assets are
popular, show active regions and report exact viewing details to the customers.
CDN nodes are deployed in multiple locations, often over multiple backbones. These nodes
cooperate with each other to satisfy requests for content by end users, transparently moving
content to optimize the delivery process. Optimization can take the form of reducing bandwidth
costs, improving end-user performance, or increasing global availability of content.
The number of nodes and servers making up a CDN varies, depending on the architecture, some
reaching thousands of nodes with tens of thousands of servers on many remote PoPs. Others build a
global network and have a small number of geographical PoPs.
Requests for content are algorithmically directed to nodes that are optimal in some way. When
optimizing for performance, locations that are best for serving content to the user are chosen. This
may be measured by choosing locations that are the fewest hops or fewest number of network
seconds away from the requesting client, so as to optimize delivery across local networks. When
optimizing for cost, locations that are least expensive may be chosen instead.
In an optimal scenario, these two goals tend to align, as servers that are close to the end user may
have an advantage in serving costs, perhaps because they are located within the same network as
the end user.
Content Delivery Networks augment the end-to-end transport network by distributing on it a variety
of intelligent applications employing techniques designed to optimize content delivery. The
resulting tightly integrated overlay uses web caching, server-load balancing, request routing, and
content services. These techniques are briefly described below.
Because closer is better, web caches store popular content closer to the user. These shared
network appliances reduce bandwidth requirements, reduce server load, and improve the
client response times for content stored in the cache.
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Server-load balancing uses one or more layer 4–7 switches, also known as a web switch,
content switch, or multilayer switch to share traffic among a number of servers or web
caches. Here the switch is assigned a single virtual IP address. Traffic arriving at the switch
is then directed to one of the real web servers attached to the switch. This has the
advantages of balancing load, increasing total capacity, improving scalability, and providing
increased reliability by redistributing the load of a failed web server and providing server
health checks.
A content cluster or service node can be formed using a layer 4–7 switch to balance load
across a number of servers or a number of web caches within the network.
Request routing directs client requests to the content source best able to serve the request.
This may involve directing a client request to the service node that is closest to the client,
or to the one with the most capacity. A variety of algorithms are used to route the request.
These include Global Server Load Balancing, DNS-based request routing, Dynamic metafile
generation, HTML rewriting, and ‘anycasting’. Proximity—choosing the closest service node—
is estimated using a variety of techniques including reactive probing, proactive probing, and
connection monitoring.
Simple CDNs require manual asset copying. Earlier CDNs used active web caches and global
hardware load balancers. Modern CDNs use cheap and simple edge servers and intelligent central
CDN management technologies that distribute assets dynamically.
Several protocols suites are designed to provide access to a wide variety of content services
distributed throughout a content network. The Internet Content Adaptation Protocol (ICAP) was
developed in the late 1990s to provide an open standard for connecting application servers. A more
recently defined and robust solution is provided by the Open Pluggable Edge Services (OPES)
protocol. This architecture defines OPES service applications that can reside on the OPES processor
itself or be executed remotely on a Callout Server. Edge Side Includes or ESI is a small markup
language for edge level dynamic web content assembly. It is fairly common for websites to have
generated content. It could be because of changing content like catalogs or forums, or because of
personalization. This creates a problem for caching systems. To overcome this problem a group of
companies created ESI.
Hybrid P2P – CDN systems
Peer-to-peer (P2P) is increasingly used in combination with CDNs to deliver content to end users.
The Hybrid P2P-CDN system is considered an extension to conventional CDN content
delivery/distribution services. The real strength of P2P shows when one has to distribute highly
attractive data, like the latest episode of a soap opera or some sort of software patch/update, in a
short period of time. Ironically, the more people download the (same) data, the more efficient P2P
is, slashing the cost of the peering fees a CDN provider has to pay due to inter-peer delivery (in
comparison to the same amount of data distributed using traditional techniques). On the other
hand, ‘long tail’ type material does not benefit much from P2P delivery since to gain advantage
over traditional distribution models a P2P-enabled CDN has to force storing (caching) of data on
peers and this is usually not desired by users and rarely enabled.
Contrary to popular belief, P2P is not limited to low-bandwidth A/V signal distribution. There is no
technical boundary, built-in inefficiency or by-design flaw in peer-to-peer technology preventing
distribution of Full HD audio + video signal at, for example, 8 Mbit/s. It's just environmental factors
such as low upload bandwidth or the lower computing power of CE devices that prevent HD
material being widely available in P2P CDNs.
There have been several trials done by the Telewizja Polska SA, Poland's national broadcaster,
involving live 800 kbit/s and 1.5 Mbit/s Windows Media simultaneous streams delivered over public
Internet proving that the limiting factor in P2P delivery systems is the upload capacity of peers,
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which in DSL environments vary from 1/4 to even 1/16 of the download bandwidth.
There are some concerns about lack of QoS control over P2P distribution, but it is being developed
and implemented by the P2P-Next consortium (see §17).
A short history of P2P
Peer-to-peer (P2P) technology evolved over the years from a simple ‘share amongst friends’
concept to complex implementations involving specially developed techniques such as ‘ISP-aided
Biased Query Search’ and multilevel trust, reputation and the swarm concepts found for example in
the Tribler social P2P implementation that was derived from BitTorrent
In fact, the root idea behind P2P concept can be traced back to the beginning of the Internet itself.
ARPANet, a military project from which Internet has evolved, used the concept of peering, packet
routing over interconnected network and traffic travelling from A to B via peers to overcome single
point of failure in case of an atomic attack. It is the idea of multiple shared connections and
utilizing both up- and down-links that brings P2P and ARPANet close together.
Up until 1999 the dominant data exchange model was the client-server approach. It proved
efficient for small files or requests (cf. WWW/HTTP). For larger data sets, the old-style
downloading method was just not enough and the idea of client-server architecture did not support
the sharing needs Internet users started to demand. First of all, the clients did not utilize the
‘reverse channel’ (upload) for anything other than protocol-related acknowledgements or small
requests to servers. The sharing concept was hard to achieve since client-server technique did not
fit well and there was virtually no way to view who-had-what, apart from browsing flat-text files.
Even when a user was lucky enough to have a then not-that-uncommon symmetrical DSL or E1
Internet connection, the sharing rapidly saturated the upload capacity, even when most people
downloaded the same file.
In addition, the data was scattered amongst users, with everyone having a different set, some
pieces could be found in others' data sets and some were exclusive just to one user. A way had to
be invented to make the data sets both trackable and queryable.
Note: the use of the term ‘data set’ might be somewhat misleading, and perhaps academic and
artificial but it is done on purpose to move away from the real origin of P2P technology – the illegal
distribution of MP3 files ripped from CDs. This early use of P2P caused a major blow to that
technology's reputation and almost since the very start; P2P has had to prove it is ‘not merely a
technology for subverting intellectual property rights’.
Another thing is worth noting: the history of P2P shows that an advanced computer technology can
be developed by its users from the ground up, with companies catching up only when it is mature
and stable enough for commercial uses and when it has proved its superiority over traditional
client-server architectures.
First generation P2P
One of the first applications of the ‘applied P2P approach’ was the Napster project conceived by
Shawn Fanning who, motivated by his college roommate who was having difficulty accessing music
files, wrote a tool to download and share music files amongst friends. It enabled users to share
data, query the metadata describing the content itself and to make direct connections to parties
willing to share.
This was also the concept for eDonkey 2000 network which was basically a star-based data indexing
service with direct inter-peer file transfers but very much in a server-client fashion.
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Applying the P2P concept to data sharing was revolutionary but both Napster’s and eDonkey’s
downside was the centralisation of metadata which could easily lead to networks dieing instantly
when the central server(s) were shut down, as was Napster’s case. Without the central ‘aid’
provided by the server, no file-tracking or inventory of data was available. The user community
learned that in order for a network to run freely without a single point of failure, metadata search
has to be decentralised.
Second generation P2P
Even before Napster was shut down due to legal action there were attempts made to create faulttolerant peer-to-peer file sharing networks (as in the original ARPAnet concept). The outcome was
the Gnutella network, a completely decentralised file sharing framework in which metadata was
distributed and had no single point of failure. This seemed like an antidote to a centralised
approach but it turned out that treating all nodes as equal created its own bottlenecks and did not
scale well. In fact it scaled very badly; finding the data was difficult since the query has to be sent
to peers and this generates traffic in a pyramidal fashion, with far-distant nodes replying to the
original query minutes after the data was sent into the network. The volume of query- and
protocol-related data escalated, making the network slower to respond and making it difficult to
obtain rare data. When there are a large number of peers in the network, most of the traffic
consists of queries and metadata replies with no real file-transfer being performed. This ‘queryflood’ phenomenon was unacceptable.
This experience caused some enthusiasts from Sweden, Denmark and Estonia to establish
FastTrack, a network consisting of normal peers and ‘supernodes’. This effort, carried out in 2001,
was so successful that it was later adapted for the Skype and Joost services, with the first of these
itself making computing history.
The concept of ‘supernodes’ was to improve network response to metadata queries with caching
and tracking of peers. Considered by some as a ‘generation 2.5’ P2P network, FastTrack spawned
the infamous Kazaa client which, apart from being a malware and spyware vehicle, proved that
some sort of server ‘aid’ is required for P2P networks to scale well.
The same concept of supernodes has been implemented and extended in numerous file sharing P2P
networks. The main 2.5G P2P entity is the next generation eDonkey network (started in 2002)
which introduced the concept of splitting large files into small chunks and increasing throughput by
downloading different chunks of a file from a number of peers at the same time and thus making
the network more resistant to peers leaving.
Another 2.5G network is Freenet, which has been in development since 2000 (release 0.7 of
Freenet was launched in 2008). Freenet has an interesting approach since it employs numerous
techniques that make second-generation P2P networks become more efficient, ‘unbreakable’ and
‘uncensorable’, such as key-based routing via distributed hash tables and nodes constantly
attempting to swap locations (using the Metropolis–Hastings algorithm) in order to minimize their
distance to their neighbours. Freenet’s implementation of distributed storage and data caching
make it a very advanced peer-to-peer distribution model. Similar techniques are being used to
stream live video in a P2P network (for example, Octoshape).
An alternative approach to peer-to-peer and file sharing was begun by Bram Cohen in 2001. The
idea was presented at the first CodeCon conference at the DNA Lounge in San Francisco, California.
In this approach a small ‘torrent’file named, for instance, ‘MyFile.torrent’ describes the files being
shared and the means of peer tracking. Special servers called ‘trackers’ help the peers to find
other peers hosting the file chunks they need. In the event of tracker failure, a different ‘torrent’
file could be used or an alternative tracker can be selected as this information is ‘encoded’ into
the original ‘torrent’ file. Alternatively one might use the distributed tracker technique known as a
distributed hash table (DHT) overlay network, which elects various nodes to index certain hashes,
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thus making the network fault-tolerant and the metadata dynamically decentralised.
One very important aspect of the BitTorrent protocol is that it applies the chunked file data model
to achieve much lower cost to the content provider, much higher redundancy, and much greater
resistance to abuse or to ‘flash crowds’ than a regular client-server distribution model, or treebased P2P overlay networks
The introduction of ‘torrent’ files moved the finding of data away from the P2P network itself as it
could conveniently be published, indexed and accessed over the traditional HTTP protocol. It is
considered a ‘best of both worlds’ approach to file sharing and to P2P content distribution.
Second generation P2P networks addressed open issues of decentralisation, scalability and fault
tolerance of the first generation. More or less all these were solved although no single network
stands out as ‘THE network’ or ‘THE concept’ for the future P2P development. Second generation
P2P networks still have their problems, mainly in the security area. When applied to distributing
A/V material the current 2.5G P2P networks provide enough power, intelligence and technology to
support either live (Freenet-like plus Unicast for fast channel switching) or VoD (BitTorrent-like)
distribution models.
Third generation P2P
The new wave of P2P networks has anonymity and encrypting features built in. Yet they have not
reached high levels of penetration because most current implementations incur too much overhead
in their anonymity features, making them slow or hard to use. However, in countries such as Japan
where very fast fibre-to-the-home Internet access is commonplace, a number of anonymous filesharing clients have already reached high popularity.
Generally speaking, third generation P2P networks do address many relevant issues important for
live/VoD audio-visual distribution. This report attempts to address those issues in the forthcoming
A wealth of P2P networks and clients
Most BiTorrent clients are available from The table below
shows some of the most used P2P clients and the P2P networks on which these clients can be used
for downloading audio and video files.
Table 1: Most popular P2P client software
Gnutella2, Gnutella,
eDonkey, and BitTorrent
Gnutella2, Gnutella,
eDonkey, and BitTorrent
Gnutella2, Gnutella,
eDonkey, BitTorrent
The MP2P Network
ZipTorrent BitTorrent,
MediaDefender 'decoy'!
Torrent Monster
G3 Torrent
BitTorrent, current
version 5.0.7
BitTorrent, current
version 4.4
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Bit Pump
BitTorrent, current
version 1.00
Manolito Network,
current version 3.1.0
Gnutella2, Gnutella,
eDonkey, and BitTorrent
BitTorrent, current
version 3.1
BitTorrent, Gnutella
Gnutella, Zepp
Strong DC++
Direct Connect, current
version 2.41
Gnutella and G2
BitTorrent, Gnutella,
current version 4.20.3
BitTorrent, eDonkey2000,
www.µTorrent .com
eDonkey2000, Overnet
eDonkey2000, Kad
Ares, current version
Gnutella, OpenFT, Ares
eDonkey2000, BitTorrent,
Gnutella, G2
Gnutella2, FastTrack,
eDonkey2K and Overnet
P2P networks
Currently, the five most popular P2P clients for Windows are µTorrent, BitComet, Limewire, Vuze
(formerly Azureus) and BitLord.
For MAC OS X the choice is much smaller. Amongst the most popular clients are µTorrent,
Transmission, BitTorrent and Vuze (formerly Azureus).
The most popular P2P network is BitTorrent, with the following clients capable of working on it:
ABC, Arctic Torrent, Vuze, BitComet, BitTornado, BitTorrent, BT++, G3 Torrent, Halite,
TorrentFlux, µTorrent, Warez P2P and XBT Client.
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According to the analysis available at, BitTorrent has the following strengths and
Table 2: BitTorrent strengths and weaknesses
BitTorrent Strengths
BitTorrent Weaknesses
Superior corruption managing
Trackers not very protected from legal attacks
Encryption provided
Supports only large files
High download speeds
Short-time availability for the files
Offers ‘Hash’-like link functionality with torrents
Lacks global search option
It’s open source
Your IP is known to trackers
Credit system to facilitate fair trading
BitTorrent content can be searched for at a number of dedicated websites. Among most popular
sites are the following: The Pirate Bay (contains some 600000 plus torrents, but it was taken down
by Swedish law enforcers), (some 200000 indexes), BiteNova, BitSoup, BTjunkie,, (presently having some legal difficulties), (a ‘metasearch’ engine, which is a search engine that can find other search engines),,, and many others.
Some examples of such decentralized, distributed systems are given below.
As the name indicates, Freenet is a P2P-based overlay network application that allows for user
anonymity. It permits the publication, replication, and retrieval of data while protecting the
anonymity of both authors and readers. Freenet operates as an adaptive network of identical nodes
that collectively pool their storage space to store data files and cooperate to route requests to the
most likely physical location of data. No broadcast search or centralized location index is
employed. Files are referred to in a location-independent manner, and are dynamically replicated
in locations near requestors and deleted from locations where there is no interest. It is infeasible
to discover the true origin or destination of a file passing through the network and difficult for a
node operator to determine or be held responsible for the actual physical contents of her own
Freenet is free software available from Freenet lets you anonymously
share files, browse and publish ‘freesites’ (web sites accessible only through Freenet) and chat on
forums, without fear of censorship. Freenet is decentralised to make it less vulnerable to attack,
and if used in ‘darknet’ mode, where users only connect to their friends, is very difficult to detect.
Communications by Freenet nodes are encrypted and are routed through other nodes to make it
extremely difficult to determine who is requesting the information and what its content is.
Users contribute to the network by giving bandwidth and a portion of their hard drive (called the
‘data store’) for storing files. Files are automatically kept or deleted depending on how popular
they are, with the least popular being discarded to make way for newer or more popular content.
Files are encrypted, so generally the user cannot easily discover what is in his data store, and
hopefully cannot be held accountable for it. Chat forums, websites, and search functionality, are
all built on top of this distributed data store.
Ideas and concepts pioneered in Freenet have had a significant impact in the academic world.
Freenet is based on a paper entitled ‘Freenet: A Distributed Anonymous Information Storage and
Retrieval System’ [25].
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An important recent development, which very few other networks have, is the ‘darknet’. By only
connecting to people they trust, users can greatly reduce their vulnerability, and yet still connect
to a global network through their friends' friends' friends and so on. This enables people to use
Freenet even in places where Freenet may be illegal, makes it very difficult for governments to
block it, and does not rely on tunneling to the ‘free world’.
The client that receives a packet is not able to readily establish from which client(s) this packet is
coming from. Communication on Freenet occurs by sending a request to a client you are connected
to, who in turn sends it on to another client, and so on. In Freenet, any client can insert content
resources into the network as well as search for them and retrieve them.
In order to insert resources into the network, the resource is given a title identifier which is hashed
using SHA-1 to generate a unique key to identify the resource. The resource is then associated with
that key and stored locally. A request for insertion into the network may be made in which the
resource with key attached is sent to other nodes to store. The ‘direction’ in which this packet will
travel is based upon the ‘nearness’ of its key to other keys that other nodes are storing. This means
that data with keys that are close, or near to other keys, reside close to each other in the network.
To search for a resource on the network it is necessary to know its title. The title is then hashed
using SHA-1 and a request is made for that title by sending it to the most likely place to have the
resource, based, once again, on key closeness. An initial search is then performed, searching for
nodes that contain the required key. The search backtracks if the hop count reaches zero or if
during the search a node is seen twice. When the required resource is found the search terminates
and the client with the resource begins to send the matching resource back along the search route
to the client who requested the resource. All clients along the way will cache the passing data
which helps in the replication of popular resources and means that frequently requested data is
cached and dispersed widely around the network increasing redundancy and reducing access times.
No client participating in the resource retrieval knows if the resource it is downloading and passing
on, is coming from the original publisher and going to the original requester, or whether it is just
coming from or going to some other links in the chain.
Gnutella celebrated a decade of existence on March 14, 2010 and still has a user base of several
millions. In March 2000 Nullsoft, a subsidiary of America Online, released a file sharing application
called Gnutella that allowed file swapping without the need of a central indexing server and
therefore no central point of failure, and no central point to sue for copyright infringements. On
April 10, America Online declared Gnutella to be a rogue project and terminated it, but not before
the program had been downloaded and replicated by thousands of users around the net. Over the
next few weeks the protocol was reverse engineered and Gnutella clones began to appear. In 2007,
it was the most popular file sharing network on the Internet with an estimated market share of
more than 40%. In June 2005, Gnutella's population was 1.81 million computers increasing to over
three million nodes by January of 2006.
Gnutella's architecture is similar to Freenet's in that it is completely decentralised and distributed,
meaning that there are no central servers and that all computations and interactions happen
between clients. All connections on the network are equal. When a client wishes to connect to the
network, he runs through a list of nodes that are most likely to be up or takes a list from a website,
and then connects to as many nodes as he needs. This produces a random unstructured network
Routing in the network is accomplished through broadcasting. When a search request arrives at a
client, that client searches itself for the file and broadcasts the request to all its other
connections. Broadcasts are cut off using TTL (time-to-live) which specifies how many hops the
packet passes before clients drop them rather than broadcast them.
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Figure 2: Example of a Gnutella broadcast search. Illustrates searching,
replying, packet meeting TTL and redundant loops
There is a small degree of anonymity provided on Gnutella networks by this packet routing
technique. A client that receives a packet does not know if the client it has received the packet
from is the original sender or just another link in the chain.
Searching on Gnutella is accomplished by creating a keyword string that describes the file you want
and broadcasting that string to all your connected neighbours. Your neighbours will then in turn
broadcast that message to all their connected neighbours and so on until the packet's TTL has been
Reaching a lot of nodes for search can be quite effective. With a TTL of 7 on the packet and an
average of 8 neighbours per client, one million clients may be reached in theory. In reality this is
not the case. Optimistically, one may have up to 40000 clients on Gnutella but only 2000 to 4000 of
these clients may be reached with a search.
Upon a query match, clients create a packet that contains information on how to locate them and
the file (a URL). To route the replies, all the clients send the query replies back along the same
path they came. Following a certain time, all results will arrive back at the client who originally
sent them out. At this point the client can decide which file, if any, he wants to download.
To download a file the client creates a direct connection to the client with the file he wants and
sends a HTTP packet requesting the file. The client with the file interprets this and sends a
standard HTTP response. This process, however, removes any anonymity in the system.
Kazaa uses the FastTrack architecture which follows a 2-tier system in which the first tier consists
of fast connections to the network (Cable/DSL and higher) and the second tier consists of slower
connections to the network (modem and slower). Clients on the first tier are known as SuperNodes
and clients on the second tier are known as Nodes. Upon connection to the network, the client
decides whether he qualifies as a SuperNode or not. If he qualifies, he connects to other
SuperNodes and starts taking connections from ordinary Nodes. If he only qualifies as a Node, he
finds a SuperNode that will allow him to connect to them and does so. In such a two-tier topology
the nodes at the centre of the network are faster and therefore produce a more reliable and stable
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Routing on FastTrack is accomplished by broadcasting messages between the SuperNodes. For
example, when a Node issues a search request to the SuperNode it is connected to, the search
request is taken by that SuperNode and then broadcast to all the SuperNodes it is currently
connected to. The search continues in this way until its TTL has reached zero. Every SuperNode
that it reaches searches an index that contains all the files of its connected Nodes. This means,
that with a TTL of 7 and with an average number of Nodes per SuperNode of 10, a search request
will search 11 times more nodes on a FastTrack network than on Gnutella. Unfortunately, since the
searches are broadcast, the network will still produce enormous amounts of data that needs to be
passed from SuperNode to SuperNode. However since the SuperNodes are guaranteed to be
reasonably fast it does not produce as large a problem as on Gnutella.
Routing of replies follows the same lines as Gnutella. Replies are routed back along the path that
they came from, until they reach the clients that originally issued them. A large problem with this
type of routing in Gnutella was that clients making up its backbone were very transient and
connected and disconnected to the network very sporadically which meant that packets being
routed back along the path they came along could find the path gone because a link in the chain
had disconnected. This problem occurs less on Kazaa as clients making up the backbone are
guaranteed to be faster and more stable and therefore paths for return routing packets should be
more reliable.
Downloading on Kazaa is the same as on Gnutella. Once the location of the file has been found, the
client that wants the file connects to the client that hosts the file and sends a HTTP request for the
file. The client hosting the file interprets the request and sends a HTTP response. The HTTP
headers used in Kazaa have been modified to accommodate extra information such as metadata but
standard HTTP/1.1 headers are supported. This means that files can be downloaded from Kazaa
clients through a web-browser such as Internet Explorer or Mozilla.
Unfortunately, although the FastTrack topology is decentralised, one implementation of Kazaa
requires that all clients register with a central server before being allowed to connect to the
network which invalidates all the advantages of having a decentralised topology. Kazaa was
undergoing legal proceedings with the RIAA (Recording Industry Association of America) but Kazaa's
legal issues ended after a settlement of $100 million in reparations to the recording industry.
Kazaa, including the domain name, was then sold off to Brilliant Digital Entertainment, Inc.
Today Kazaa operates as a monthly music subscription service allowing users to download unlimited
Programmer Bram Cohen designed the protocol in April 2001 and released a first implementation on
July 2, 2001. It is now maintained by Cohen's company BitTorrent, Inc. BitTorrent is a peer-to-peer
file sharing protocol used to distribute large amounts of data. BitTorrent is one of the most
common protocols for transferring large files, and by some estimates it accounts for about 35% of
all traffic on the entire Internet. The initial distributor of the complete file or collection acts as the
first seed. Each peer who downloads the data also uploads them to other peers. Because of this,
BitTorrent is extremely efficient. A minimum of one seed is needed to begin spreading files
between thousands of users (peers). The addition of more seeds increases the likelihood of a
successful connection exponentially. Relative to standard Internet hosting, this provides a
significant reduction in the original distributor's hardware and bandwidth resource costs. It also
provides redundancy against system problems and reduces dependence on the original distributor.
Usage of the protocol accounts for significant Internet traffic, though the precise amount has
proven difficult to measure. There are numerous BitTorrent clients available for a variety of
computing platforms. According to isoHunt the total amount of content is currently more than 1.1
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A BitTorrent client is any program that implements the BitTorrent protocol. Each client is capable
of preparing, requesting, and transmitting any type of computer file over a network, using the
protocol. A peer is any computer running an instance of a client.
To share a file or group of files, a peer first creates a small file called a ‘torrent’ (e.g.
MyFile.torrent). This file contains metadata about the files to be shared and about the tracker, the
computer that coordinates the file distribution. Peers that want to download the file must first
obtain a torrent file for it4, and connect to the specified tracker, which tells them from which
other peers to download the pieces of the file.
Though both ultimately transfer files over a network, a BitTorrent download differs from a classic
full-file HTTP request in several fundamental ways:
BitTorrent makes many small data requests over different TCP sockets, while web-browsers
typically make a single HTTP GET request over a single TCP socket.
BitTorrent downloads in a random or in a ‘rarest-first’ approach that ensures high availability,
while HTTP downloads in a sequential manner.
Taken together, these differences allow BitTorrent to achieve lower cost to the content provider,
higher redundancy, greater resistance to abuse and can more easily handle ‘flash crowds’ than a
regular HTTP server. However, this protection comes at a cost: downloads can take time to rise to
full speed because it may take time for enough peer connections to be established, and it takes
time for a node to receive sufficient data to become an effective uploader. As such, a typical
BitTorrent download will gradually rise to very high speeds, and then slowly fall back down toward
the end of the download. This contrasts with an HTTP server which rises to full speed very quickly
and maintains this speed throughout (but is more vulnerable to overload and abuse).
The peer distributing a data file treats the file as a number of identically-sized pieces, typically
between 64 kbyte and 4 Mbyte each. The peer creates a checksum for each piece, using the SHA-1
hashing algorithm, and records it in the torrent file. Pieces with sizes greater than 512 kB will
reduce the size of a torrent file for a very large payload, but this reduces the efficiency of the
protocol. When another peer later receives a particular piece, the checksum of the piece is
compared to the recorded checksum to test that the piece is error-free. Peers that provide a
complete file are called seeders, and the peer providing the initial copy is called the initial seeder.
The exact information contained in the torrent file depends on the version of the BitTorrent
protocol. By convention, the name of a torrent file has the suffix .torrent. Torrent files have an
‘announce’ section, which specifies the URL of the tracker, and an ‘info’ section, containing
(suggested) names for the files, their lengths, the piece length used, and a SHA-1 hash code for
each piece, all of which is used by clients to verify the integrity of the data they receive.
Torrent files are typically published on websites or elsewhere, and registered with a tracker. The
tracker maintains lists of the clients currently participating in the torrent. Alternatively, in a
trackerless system (decentralized tracking) every peer acts as a tracker. This is implemented by the
BitTorrent, µTorrent, rTorrent, KTorrent, BitComet, and Deluge clients through the distributed
hash table (DHT) method. Vuze also supports a trackerless method but is incompatible (as of April
2007) with the DHT offered by all other supporting clients.
Users browse the web to find a torrent of interest, download it, and open it with a BitTorrent
client. The client connects to the tracker(s) specified in the torrent file, from which it receives a
list of peers currently transferring pieces of the file(s) specified in the torrent. The client connects
Torrent files can be obtained legally from a number of web sites including (movie trailers in HD, and
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to those peers to obtain the various pieces. Such a group of peers connected to each other to share
a torrent is called a swarm. If the swarm contains only the initial seeder, the client connects
directly to it and begins to request pieces. As peers enter the swarm, they begin to trade pieces
with one another, instead of downloading directly from the seeder.
Clients incorporate mechanisms to optimize their download and upload rates; for example, they
download pieces in a random order to increase the opportunity to exchange data. This is only
possible if two peers have different pieces of the file.
The effectiveness of this data exchange depends largely on the policies that clients use to
determine to whom to send data. Clients may prefer to send data to peers who send data back to
them (a tit for tat scheme), which encourages fair trading. But strict policies often result in
suboptimal efficiency; for instance, when newly joined peers are unable to receive any data
because they do not have any pieces yet to trade or when two peers with a good connection
between them do not exchange data because neither of them wants to take the initiative. To
counter these effects, the official BitTorrent client program uses a mechanism called ‘optimistic
unchoking’, where the client reserves a portion of its available bandwidth for sending pieces to
random peers (as opposed to the known, preferred peers), hoping to discover even better partners
and to ensure that newcomers get an opportunity to join the swarm.
Codenamed Falcon5, the µTorrent client has an easier, more secure and more complete web UI as
well as support for streaming and remote downloading. Developed by BitTorrent Inc., µTorrent
Falcon brings plenty of change to the BitTorrent client currently in use by more than 50 million
people a month. Below we sum up some of the key features.
Allowing users to access their BitTorrent downloads from anywhere through a simple web-interface
is one of the main goals of the Falcon project. Without having to configure µTorrent and home
networks so that they can be accessed remotely, users can simply browse to the Falcon page and connect to their client instantly.
The easy to use web interface is extremely secure and is a major improvement over the Web UI
currently available. When logged in, it gives users all the controls they are familiar with in their PC
client. Torrents can be added, paused and removed using an interface with a look and feel
identical to that of the µTorrent application.
Figure 3: µTorrent Falcon web interface
Aside from the added security and easy setup, accessing your torrents via the Falcon web-interface
offers another advantage – remote downloading. Once a file has finished downloading you can
transfer a copy of the file to a remote computer via the web-interface.
See TorrentFreak, 31 January 2010.
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Another new feature of the Falcon project is the added option to stream video files while
downloading. Instead of having to wait until a file has finished downloading, users can already start
watching video provided that the download speed is sufficient. The Falcon intention is to transform
getting media using µTorrent from a ‘load-wait-watch-tomorrow’ to more of a ‘point-click-watch’
Also new in the Falcon release is the ‘Send Torrent’ feature. This feature is particularly useful
when you want to share torrents with people who do not have a BitTorrent client installed yet.
Right clicking a torrent in µTorrent shows a ‘Send Torrent’ option which then brings up a URL which
is a direct link to a download of the µTorrent client with the torrent file included.
The Falcon release makes it easier for users to find torrents. It provides a better ability for torrent
sites to promote content or search within the client. The µTorrent client comes with a built in
torrent search engine.
The latest alpha release also has a ‘minify interface’ option and the development team is also
working on speed improvements, UI improvements and optional file security features.
Tribler is a P2P-based application that enables its users to find, enjoy and share video, audio,
pictures, and much more. Tribler is developed at the Delft University of Technology and the Vrije
Universiteit Amsterdam. The Tribler software integrates state-of-the-art research into network
technology, P2P networks, video streaming and user interaction. Tribler aims for an open source,
fully decentralized peer-to-peer network, available for everybody, in every part of the world.
Tribler supports UPnP to open a listening port on the firewall automatically.
When the Tribler application program is started, it will automatically start searching other users
that have Tribler running on their computer. When a connection is established, it starts exchanging
information. First it exchanges personal information (such as your avatar picture, your friends list,
download history, etc.) and information about files that are available in the network. These files
can be personal, shared files, but also files that one has received from another person.
The information about the discovered files and persons is available in the Tribler program. By
browsing through the files and persons each user can find their preferred files and users. The
Tribler program helps the user by giving extra information about each item (whether it is a file or a
person) and also shows what other users think about it. When the user finds a person they like, he
can add this person as a friend. An interesting file can be downloaded and will be available in the
user’s library. When the user presses download, his computer will make an inventory of which
computers actually have this file (or a part of it) and then will download the parts from the
different computers.
Tribler has three goals in helping the user: to find, consume and share content. Through improved
search functionality the user searches the content of other Tribler users, and the content of large
video web portals such as Youtube and Liveleak. Users can browse through different categories
such as video, audio, pictures, etc. and also see what is most popular and what is made available
recently. By making friends and getting in touch with users with similar tastes, the user can find
content that he/she might find interesting. Users can also show to their friends what they like and
what their friends should see.
Because of the integrated video and audio player the users can almost immediately start watching
their favourite videos or listen to their favourite songs.
Tribler is a social application. This means that the user can make friends with other users and can
show to others what he likes and dislikes. By sharing content the user helps other Tribler users to
enjoy his favourite content.
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P2P-enabled Adobe Flash player
The Adobe Flash player 10.1, called Stratus6, will include P2P technology that could significantly
reduce, and in some cases completely eliminate bandwidth costs incurred by the content providers.
It is offered to developers free of charge and can support both live and on-demand video
streaming. Besides video, Stratus can also be used for Flash based multi-player games and other
forms of real-time communication.
Instead of serving the media from a central server, users will provide the necessary bandwidth.
Adobe’s Stratus system serves as an intermediary in this process, managing the communications
between Flash players much like a BitTorrent tracker does for BitTorrent transfers.
Users first must agree to participate in a P2P-enabled Flash swarm, similar to how they are now
asked to indicate whether Flash can use their webcam. If users do not want to share bandwidth,
the broadcaster has the option to offer a regular stream, a degraded stream or no stream at all.
The impact of Adobe getting involved in P2P streaming could be of fundamental importance. One of
the main advantages is that Adobe Flash is already installed on the majority of computers, which
should facilitate the adoption rate among content providers.
P2P Business Environment
Delivering rich content, and in particular video and TV services, is a huge growth market
opportunity. Since 1990 the amount of traffic on the Internet has been growing incredibly fast.
There are two reasons for the growth: exponential increase in number of broadband users and the
increase in traffic consumption per user. The latter is mainly due to the growth of the video type of
content and services. The last five years, the traffic on the backbone has been growing at an
aggregate rate of about 50 to 60% per year, reaching mid 2008 an equivalent of about 0.15 Gbyte
per day per user. It is estimated that approximately one third of this traffic is delivered through a
content delivery network [6]. This huge growth in IP traffic challenges operators to efficiently
shape their network and to take advantage of new technologies to ensure quality of service for the
end user. This growth presents both threats and opportunities for all players including
broadcasters, content providers, Telcos, content delivery providers etc.
It is beyond any doubt that P2P is a very popular Internet protocol. The share of P2P protocol in the
overall Internet traffic has been subject of numerous studies. As an example, the results of a study
carried out in 2009 on the distribution of Internet backbone protocols across different parts of the
world are shown below7. It is of no surprise that the P2P protocol takes typically more than half of
the overall backbone traffic. According to [5], 65-70% of the Internet backbone traffic can be
attributed to P2P. In the last mile, 50-65% of downstream and 75-90% of upstream traffic is P2P
traffic. Moreover, P2P file sharing traffic continues to grow.
Ipoque ( performed an Internet study for 2007 assessing the impact of P2P file
sharing, voice over IP, Skype, Instant Messaging, one-click hosting and media streaming. BitTorrent
and eDonkey are the most popular P2P networks by a wide margin. The two protocols account for
70% and 97% of all P2P traffic, depending on the region. P2P is still producing more traffic in the
Internet than all other applications combined. Its average proportion varies between 49% in the
Middle East and 83% in Eastern Europe.
See TorrentFreak, 19 May 2010.
Source: EC-funded Project P2P-Next review, WP4, March 2009, Brussels
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Figure 4: P2P traffic share in different countries
Figure 5: Usage of various Internet applications (Courtesy of Ipoque, 2007)
The complete protocol distribution for Germany is shown in Table 3:
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Table 3: Protocol usage in Germany (Courtesy of Ipoque, 2007)
Protocol distribution in 2007
Germany [%]
Media streaming
The following pie chart provides an overview of BitTorrent traffic volume per content type for
Germany. The leading BitTorrent content are video files with a share between 62% in Southern
Europe and 79% in Germany.
Figure 6: Traffic volume of BitTorrent based distribution in Germany
Business Model and Cost Considerations8
The P2P delivery system is an important ingredient of the digital convergence process which is
about to drastically change the audio-visual media landscape. It will give rise to the following
disruptive shifts:
A shift from classical linear TV with a monopoly in audio-visual consumption towards nonlinear, on-demand, anytime-anywhere, cross device patterns that will change the roles of
publishers and consumers;
A shift from passive collective, linear media consumption towards active personal behaviour
at home and in mobility situations;
A shift from highly popular audio-visual content to selective disclosure of ‘long-tail’ content,
This section is based on the P2P-Next Work Package 2 results.
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servicing communities with varying and diverse interests;
A shift from awareness-building, non-interactive, expensive, interruptive TV advertisements
to targeted, non-disruptive, sales-channel oriented forms of promotion.
The use of Audiovisual Media is moving from a collective and passive approach to a personal active
approach, at home and in mobility situations outside the home. At the same time, use patterns are
shifting towards non-linear usages and away from the classic models of linear broadcast TV. The TV
set has no longer the monopoly of delivery of audiovisual content, the PC and related media
centres, mobile phones, and potentially new devices such as game consoles, notebooks, tablets,
e-books are all becoming increasingly important.
P2P Business Opportunities and Challenges
Because P2P services make use of the existing network infrastructure owned and controlled by the
network service providers, they are often called the ‘over-the-top’ or ‘overlay’ services. In most
cases, subscribers pay a flat-rate network access fee, independent of usage. This causes some
problems for the network service providers that provide for transportation of the over-the-top
video traffic but are not able to generate any associated revenues.
The P2P over-the-top content providers (such as Octoshape) may enter into direct relationship with
end users, entirely by-passing the network service provider, thus entailing potential
disintermediation of broadcasters, content packagers, service and network providers from
subscriber base. P2P is thus most suitable for user-generated long-tail (niche) content distribution.
P2P content providers may become an ‘over-the-top’ content provider, competing with both the
broadcaster and the network service provider for the same digital content services market.
Network service providers are bypassed in terms of revenues, although they in fact carry a large
part of the P2P traffic delivery cost. As a result of P2P services, the value of basic network access
services may diminish.
In order to avoid content devaluation, broadcasters should embrace P2P technologies and enter the
P2P content delivery market by themselves. Alternatively, they could outsource P2P delivery to an
external specialized P2P-delivery company.
Since P2P entails bypassing the network service provider, it faces some inherent weaknesses which
impact the P2P service providers:
The P2P service is unable to provide quality guarantees for the video service provided. Such
a best-effort service may prevent a lot of inherent value of the content to be monetized.
Competitive differentiation: The over-the-top space is very crowded and there are already
many players in the market. They all have access to the same type of content. To this end,
content or quality are not effective differentiators. Revenues and profit margins are
modest. Partnerships are emerging and collapsing every day, as the search for a viable
business model continues.
P2P Business Models
As part of its business and regulatory studies, the P2P-Next project identified five P2P-related
content delivery models:
Business Model 1 – Free Content Distribution
Business Model 2 – Advertisements Supported Distribution
Business Model 3 – A la Carte Models
Business Model 4 – Subscription Based Distribution
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Business Model 5 – Circular Content
Business Model 1: Free Content Distribution
A free content distribution model is generally performed by a public free-to-air broadcaster. This
model encompasses business models such as: ‘Give away’, partly ‘Attention grabbing’, partly ‘Use
of large repositories’ and ‘Sales support channel’. Free content distribution may aim at revenues
independent from the content itself, e.g. a free music video and revenue from resulting CD and
Ticket sales.
‘Give Away’ Model
An example of this model is the offer of free music files embedded in mobile phones. Small record
companies and individual artists who are seeking to make their name known often make their
materials available on online networks for free, with the aim of attracting attention and interest
for other revenue streams (concerts, merchandising).
‘Attention Grabbing’ Model
In the Internet environments, attention grabbing models with a large range of content as an
attractive consumer offering can be promising, at least initially. These models can attract
advertisers (e.g. using banners when consumers download software clients). If dubious, legality can
be sued (suing can attract even more attention, e.g. Napster), bought up and then developed as a
service accepted by major content owners, or simply closed down (
Business Model 2: Advertisements Supported Distribution
Typically, this model is used by a commercial broadcaster. This encompasses business models such
as: ‘Advertising’, ‘Sponsoring’, partly ‘Attention Grabbing’, ‘Customer Reach’, ‘Single-Click
product buying’. It can be linked to advertising models (click to order) if not related to content.
Advertising Models
Advertising can help financing Internet audio-visual activities. A wide range of advertising models is
available today:
Banners when consumer downloads clients and use the service thereafter.
Advertising prior to receiving content (as a condition).
Regular advertising breaks (as in traditional TV with 30 second slots), or shorter breaks of a
few seconds, making a fast forward unnecessary. Examples: Hulu (USA) for film and for
music: Spiral Frog, Spotify,, Qtrax.
Advertising can indirectly finance content.
Sponsoring Models
Example: Coca Cola product placement in the American Idol TV shows.
Business Model 3: Pay-Per-View Distribution
An example is a video rental store going electronic. This model can encompass business models as:
‘A la carte’.
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A la Carte Model
This model applies to a seller of audio-visual items. Example: Apple iTunes which is the first and
still the leading supplier of music items. Apple is mainly interested in selling iPods and accepts low
margin on sales of music. Other services in the music sector: Klicktrack, CDON, Amazon MP3, Media
Markt, Tesco.
Generally, a range of choices available on iTunes cannot compete with what is available in filesharing networks. Remuneration to artists/composers by iTunes is low, as opposed to very high
remuneration offered to artists by record companies (as percentage of consumer cost). Selling
music with a low margin (in order to market something else) may hinder development of a
competitive retail market but can work well for ‘impulse’ purchases.
Business Model 4: Subscription Based Distribution
This model encompasses business models such as: ‘Flat rate’ and, partly, ‘Use of large
repositories’. An example: a jazz music events producer.
Flat Rate
The Flat Rate model can be applied to both download and streaming services as well as a
combination of the two (such as in Rhapsody). It can involve towards a variety of models,
frequently combined with other variants (a la carte downloads as in the case of Rhapsody or
Advertising as in Swedish Spotify). Many of these models often have the condition that what has
been downloaded during the subscription period disappears if the subscription expires (e.g. Napster
2). Or if it is bundled with another subscription, e.g. broadband payment, the downloaded content
disappears if one changes operator (example: TDC Denmark). At least one film distributor,
Headweb (Sweden) considers offering a pure streaming flat rate service. Generally, consumers
show limited favour of losing what they ‘have paid for’ – this tends to clash with the notion of
ownership which is still governed by the physical world’s rules. Future solutions may involve
blanket flat rate licences combined with broadband subscriptions.
Use of Large Repositories
Models based on accumulating large repositories of rights involve a) buying or selling and b) suing
when such materials turn up in other business activities. Vertical integration in the media content
industries has facilitated this model (and competition law has not been able to hinder the
Rights repositories and indirect incomes (e.g. from private copying levies, neighbouring rights
payments) has also allowed major rights holders to earn more from such incomes than from
traditional exploitation of rights (new creativity). Creativity is limited to finding new ways of
generating money from rights, often without needing to remunerate the creators (again the
example of the record companies buying shares in YouTube and generating an ‘equity profit’ which
was not ‘royalty related profit’). This trend could lead to a withering of societal support for IPR
regimes, both amongst creators as well as the general public. Artists’ managers are beginning to
raise this as a legal issue with the major record companies/publishers.
Business Model 5: Circular Content
E.g. Super distribution, mash ups. Encompasses business models as: ‘Super distribution’, ‘Prosumer
co-design’. Traditionally content is produced by professional content producers and solely
consumed by users. Circular content describes an indefinite number of ‘re-produced’ content. This
business model could for example reward users for super distributing contents (monetary or tokens)
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Super-distribution of content
The expression ‘super-distribution’ means ‘(...) an approach to distribute digital products as
software, videos, and recorded music, in which products are entirely free of copy protection and
are made publicly available and distributed (...).’ In the meaning of a circular content model
super-distribution takes place in controlled environments, for instance, in allowing certain
explicitly marked videos or parts of videos to be distributed freely. To encourage superdistribution, e.g. for promotional contents, users could be rewarded by tokens, bandwidth or even
monetary units.
Super-distribution of recommendations
This case of super distribution is very close to public playlist and involves individual consumers
acting as agents, recommending and assisting further sales and receiving some form of reward for
this. A number of such systems have emerged but have not survived the test of time.
(linked closely to the Kazaa file sharing system) was one such. Another was Weedshare. They seem
to suffer from allowing elements of ‘pyramid selling’ to infuse the system. A recent example in
Sweden is Ameibo for film distribution. Selling on a widget which allows friends also to be part of a
network is another alternative (e.g. akin to associations offering perks to those who get their
friends to join).
P2P use cases
These cases show some typical examples where the P2P distribution mechanism can be used.
However, they do not imply that P2P is the only technology which can be used, as other Internet
distribution technologies (such as CDN, IP Multicasting) may be used to perform the same task with
similar effect.
The P2P technologies are most useful in cases where the same content is distributed across the
Internet to a large number of users at the same time. The same content is stored on a large number
of devices at any given moment, and shared cooperatively between them.
Streaming media services
A user (we’ll call her Anna) is looking for a very popular scheduled programme to be streamed over
broadband. She points her P2P-enabled Internet device to a content provider, selects a service and
the TV or radio content is streamed in real time to her P2P-enabled Internet device via P2P.
P2P-enabled Internet-format catch-up TV services
Anna has booked to record a broadcast programme on her DVR which is connected to a P2P-enabled
Internet network. At recording time there is a booking clash due to a late running schedule and the
recording cannot be started. The device connects to the broadcaster’s P2P-enabled Internet-format
catch-up TV service that delivers the programme (and associated adverts) to the P2P-enabled
Internet device. The P2P-enabled Internet-format catch-up TV service uses some P2P-enabled
Internet devices as sources among those devices that have been connected to the programme when
it was broadcast.
P2P-enabled Internet device to record broadcast programmes
Anna has an interest in a specialist topic. She enters keywords into her P2P-enabled Internet device
related to this topic. The device will then periodically check Internet format metadata provided by
broadcasters on the open Internet. In the future Anna is informed whenever there are any
programmes that are due to be broadcast that may match her interest, or the device may
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speculatively record the broadcast for her. The broadcaster may simultaneously push content (e.g.
during the night when the network load is relatively low) via P2P to all users in possession of a P2Penabled Internet device and that subscribe to this specialist topic.
Progressive download services
Anna points the P2P-enabled Internet device to a content provider, selects a service and the
content starts downloading to her device, so that she is able to watch it after a short time and
before the download is completed. This service is available via a P2P distribution mechanism.
Deferred download services
Anna points the P2P-enabled Internet device to a content provider, selects a service and the
content starts downloading to her device. The download time can be significantly shortened by
using a P2P approach compared to conventional Unicast.
Broadcast content related URI available from P2P-enabled Internet
Anna is watching a film on a broadcast service. She presses the ‘info’ key which displays the related
URI (or EIT) provided information. Her P2P-enabled Internet device also connects to the provided
URI and downloads much richer information including reviews, cast lists, recommended films, etc
via P2P connection.
Protected content with Portal
Some (multiple) Internet service providers require users to pay to access their content, and also
control the use of the content by the user following acquisition. Anna buys a P2P-enabled Internet
device supporting both free and paid for content. She is able to access both free and paid for
content from all Internet service providers that operate P2P services. Anna registers with a portal
(e.g. by registering using a web interface), and is then able to buy content from all providers
associated with that portal without separately registering with each provider. She is subsequently
able to use her P2P-enabled Internet device to access this content, subject to restrictions placed
by the provider. Bob does not pay and is not able to access the content.
Protected content without Portal
Some (multiple) P2P-enabled Internet service providers require users to pay to access their
content, and also control the use of the content by the user following acquisition. Anna buys a P2Penabled Internet device supporting both free and paid for content. She is able to access both free
and paid for content from all P2P-enabled Internet providers. In order to purchase content from a
provider, Anna separately enters a contractual relationship (e.g. by registering using a web
interface) with each provider and pays for access to some content. She is subsequently able to use
her P2P-enabled Internet device to access this content, subject to restrictions placed by the
provider. Bob does not pay and is not able to access the content.
PIP to display signing services
Anna's friend is hearing impaired and requires a signing service to be able to enjoy broadcast
services. A broadcaster provides signing services for certain broadcasts and uses open Internet to
stream these signing services synchronously to hybrid broadcast/broadband Internet-enabled
devices. The signer (or its avatar) is displayed in a small PIP window which can be moved and
resized on the main display. EPG (or BCG) informs of the programmes that include signing services.
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If a large number of users subscribe to the signing services, it may be worthwhile for the service
provider to use the P2P-enabled Internet distribution approach for these services.
6.10 P2P-enabled IPTV HNED accessing CoD services
Anna selects service discovery from her HNED and discovers that CoD (Content on Demand) services
are available from managed network based service providers and Open Internet based service
providers. She decides to configure her HNED to access the CoD guides of a managed network based
IPTV provider and an open Internet based provider. She is able to browse both content guides and
select to stream or download content from either provider. The CoD content which is available for
download or streaming over the Internet can be distributed over a P2P-enabled Internet network to
the general user.
6.11 Broadcast subtitles to be carried by P2P
Anna can speak a language which is not broadcast as subtitles. However the broadcaster has made
DVB subtitle data for a specific programme accessible on the open Internet. She is able to select
the language of the subtitle data. Her P2P-enabled Internet device is capable of receiving the
subtitles of her choice. Her P2P-enabled Internet DVR records the broadcast programme and
downloads the subtitle data. At playback time the recorded programme and subtitles are
synchronised and displayed.
6.12 P2P-enabled Internet DVR to record broadcast content
Anna is using a P2P-enabled Internet device for previewing the content which is due to be
broadcast shortly via a terrestrial channel. At a suitable point a dialogue box informs her of the
option for her P2P-enabled Internet DVR to schedule a recording of the full quality broadcast, or if
the broadcast is starting imminently then to switch to the service immediately.
6.13 Protected content on multiple devices
Anna owns several Internet devices which may be part of a home network. Content provider
ContentCo is able to sell content to Anna that she or members of her family can consume on any of
her Internet devices. Some of these devices may be P2P enabled, so that they can access TV
services via P2P networks.
6.14 Picture-in-Picture (PIP) to display Internet content related to main
Anna’s P2P-enabled Internet device supports picture-in-picture (PIP). She is watching a broadcast
sporting event which signals that there are alternate viewing angles available. Anna selects this
option. The main display continues to show the broadcast programme. The PIP window displays an
alternate viewing angle streamed over the open Internet on a ‘best endeavour’ basis. Anna can
cycle through a number of alternate angles in the PIP window.
6.15 Pre-positioned download services
Anna registers her interest in content with her service provider. The content provider downloads
the selected content in accordance with her previously expressed preferences. The content can be
pushed to the groups of the same taste or preferences via P2P.
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6.16 Customized Programming Guides
Anna’s P2P-enabled Internet device shows her a list of content to be broadcast. This Programme
information is similar to an EPG and it can be customized based on her interests. She can be shown
different lists such as her favourite channels, recommended channels from a portal, or channels of
a specified genre in the EPG.
Broadcast Technical and Commercial Requirements for a Viable P2P
This section provides the commercial requirements, as seen from the broadcasters’ perspective, for
the open Internet P2P distribution of audio-visual content (together with associated data) by means
of the standardised CE (consumer electronics) devices (rather than PCs).
Rather than specifying the CE devices, their required functionalities are given. These CE device
functionalities may be implemented either in software or hardware (or a combination of the two)
and may be embedded in a set-top box, TV receiver, hand-held device, along with any other
The content can be delivered either in the form of the real-time television/radio streams
(‘channels’) or/and on-demand files. The latter can be downloaded (and rendered after having
been downloaded) or progressively downloaded (rendered almost immediately after downloading
has started.
Any method of distribution via the Internet requires a means of performing the following tasks:
Allowing consumers to discover and find content
Allowing consumers to select content for consumption
Transferring the content to the consumer
Reducing the amount of data by using audio and video codecs in order to adjust data rates
to the available channel bandwidth
Provisioning of the infrastructure to enable users to access the content
Some methods provide additional functionality:
Allowing consumers to subscribe to content, to be automatically provided with future
editions, episodes, etc.
Payment methods
Supporting geo-restriction (geo-location), by restricting access to the content to geographic
areas for copyright enforcement,
Supporting rights management, by restricting access to paid subscribers, etc. or restricting
the use of the content,
Supporting a social model, allowing consumers to contribute reviews, ratings, referrals, etc.
In November 2007, EBU Project Group D/P2P was tasked with providing a basis for the
standardisation of a system allowing for access to the content available to the general public across
open Internet P2P networks.
Today, media delivery over the Internet implies the use of (relatively complex and expensive)
computing devices (PCs). Our incentive is, however, to facilitate and speed up commercial
introduction of Internet TV. To this end, it may be useful to replace PCs with simpler and cheaper
CE (consumer electronic) devices. As the CE devices are simple, they can accommodate only a
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subset of all features available in PCs. These features need to be standardised9.
Motivations and objectives
Broadcasters wish to deliver media over the open Internet to consumer electronics appliances such
as set-top boxes and television sets which are connected to wired or wireless broadband access
networks. TV sets seem to be the ideal target for broadcasting services delivered over the open
Internet (example: ‘catch-up TV’ services using e.g. BBC iPlayer).
There is some evidence that the CE manufacturing industry is keen to enhance their product
offering to the consumer in area of Internet connectivity. Examples: the DVB Project, Open IPTV
Forum, DLNA, along with commercial projects such as the integration of NetFlix rental downloading
directly to DVD players and iDTVs in the USA.
Ideally, horizontal markets for the media services and CE devices using the open Internet as a
distribution mechanism of audio-visual content should be established.
Horizontal market for services: The horizontal service market means that any content and/or
service provider may deliver their content or services to any CE device. Horizontal markets are very
important as they enable FTA (free-to-air) broadcasters to fulfil their public remit by providing
non-discriminatory announcement, transport and usage of their content offerings.
Horizontal market for CE devices: This implies that the CE devices used by the end user are not
specific to only one service provider or Internet access technology (ISP). Any CE device can receive
services from any provider in a given market. The horizontal market delivers many economic
advantages for CE manufacturers, since products can be engineered once and sold across multiple
regions with minimal regional variations.
Compared to PCs, CE devices are characterised by limited processing power and storage capability,
but benefit from lower power consumption and the ability to engender higher levels of trust and
reliability than PCs. Furthermore, economies of scale will drive CE device costs down.
Consequently, they are cheaper and simpler, and might be more widely accepted by consumer
markets worldwide10. Table 4 summarizes these differences.
Table 4: Principal differences between the PC and CE Devices
PC / high range functionality
CE device / low range functionality
Intel Core 2 CPU~30,000 MIPS
Embedded CPU Core ~300MIPS
≥ 1 Gbyte RAM
16 -128 Mbyte RAM
S/W Decode Audio/Video
‘On Chip’ H/W Audio/Video Decode
Lean forward UI: Keyboard and mouse
Lean backward UI: Remote control from 3m
PC Powerful, User Extendable
Device Appliance, designed for purpose
Relatively expensive
Low cost
Relatively high energy consumption
Low energy consumption (<5W)
(source: John Adam, Samsung)
The EBU D/P2P work is parallel (and complementary) to the DVB-CM IPTV group work (see for example doc. CMIPTV0379 and its revisions).
An open Internet P2P device can be combined with traditional digital TV set-top boxes or integrated in TV receivers.
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Working assumptions
The P2P network is assumed to be hybrid or decentralised (i.e. does not need a central distribution
server) and consists of (distributed) peers which up-stream and down-stream media streams and
Not all peers are created equal. Super peers may be provisioned by content providers to fill the
bandwidth gap due to asymmetries in the Internet access networks of their users.
There are two options for locating content in P2P networks:
A central metadata repository (e.g. Napster or tracker-based approaches) or
distributed metadata repository (e.g. eDonkey and other systems that leverage DHT for
torrent acquisition).
No controlling organisation is required for the system to function properly.
We define a CE device (or appliance) as a simple and affordable consumer electronics device with a
limited memory footprint and processing power. Such CE devices are peers participating in the P2P
network. It is also assumed that all CE devices are able to participate actively or passively11 in the
P2P network. The P2P distribution technologies embedded in the CE device should be standardised
according to the ‘tools approach’, as used in DVB. This means that more than one P2P technology
or policies for a specific aspect of system operation (e.g. peer selection) can be defined. One or
more standardised P2P clients may be embedded in the CE device.
As far as possible, generic solutions based on open standards and open source implementations
should be used.
Backwards compatibility of future versions of the standard should be mandated, though the legacy
installed base shall experience lesser features and lower performance.
System architecture
A simplified system stack is shown in Figure 7. It consists of the following layers (from the bottom
Physical, Network and Transport Layer: This layer represents the existing Internet infrastructure
network, upon which P2P transport is overlaid.
Content play-out
Content discovery and retrieval
Social networking
Network awareness / peer discovery
Transport IPv4/6
Figure 7: Definition of I1 and I2 Interfaces within the P2P system architecture
Passive participation implies a stand-by status of the CE device and it does not require active user involvement. Passive
participation may help improve the efficiency of the P2P network.
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Peer discovery layer: This layer represents mechanisms for search and discovery of peer CE
devices that share the same P2P standard client and are able to share/exchange content.
Interface I1 between bearer and P2P system functionalities is derived from the OSI reference model layers.
An important task of I1 is to provide bidirectional transport and measurements of connection to peers in
order to optimise the transport.
Interface I2 interfaces the P2P system which may host a metadata repository and the functions of a P2Penabled device which renders the content and processes metadata.
Security layer: This layer prevents any malicious peers wreaking havoc in the P2P network by
spreading viruses or by trying to make resources unavailable. This layer is designed to achieve
availability of files/streams and peers, file/streams authenticity, peer anonymity, payments and
access control. The latter may restrict access to media resources only to those peers that have the
rights to access those resources.
Social networking layer: This layer specifies the social networking characteristics of the P2P
system such as communities, user profile, friends, rating, tagging, recommendations and
personalisation, reputations, message boards, chatting, etc.
Content discovery and retrieval: content-related metadata, content search, rights management
(DRM), watermarking and fingerprinting, programme guides (EPGs), etc.
Content play-out: Audio/video decoding, content rendering, data display, presentation facilities,
content storage, PVR.
Figure 8 is another perspective of the system architecture.
Figure 8: Classification of market devices
Figure 9 illustrates the concept of a P2P infrastructure and positions a standardised P2P distribution
platform with the over-the-top services that exploit it and the value-chain. Importantly, it also
emphasises the need for a trust platform to enable implementation of the business models
identified earlier.
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Figure 9: Concept of a P2P-infrastructure
General P2P-related requirements
A CE device should enable open Internet access via a broadband connection (via cable or
xDSL, wireless), in order to locate and consume open Internet content and services.
CE devices should be able to connect to both server-based (Unicast/CDN, Multicast)
services as well as P2P-based services via either bridged or routed access.
The P2P clients should be standardised by competent bodies and should be embedded in
the CE device.
The CE device functionality is either a part of an IPTV managed system or a standalone
open Internet consumer appliance (example: Internet radio appliance).
Any technical specification prepared by the international standardisation bodies should
provide a common profile of the necessary protocols and data formats required to deploy
a DVB service over the open Internet.
The CE device allows for a variety of business models in a horizontal market.
The CE device allows for collecting statistical audience data and capturing user
behaviour, while fully complying with international regulations concerning user anonymity
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and user data confidentiality. Such data should not be divulged to third parties without
the user’s consent and should not be used for commercial purposes.
P2P delivery-related requirements
The P2P based delivery and contribution of content should allow for different
implementations to enable live-streaming, progressive-download and deferred download.
However, these implementations should be able to cooperate with each other in nondiscriminating way in terms of quality, performance/quantity and bandwidth sharing,
although peers must inevitably discriminate based on traffic localisation and the priority
of reducing access latencies.
A P2P architecture should allow for scalability in terms of the number of clients. This
should be true for a typical network case where the upstream capability of some peers
may be limited as well as there being adverse issues such as heavy usage, high network
packet loss rate and jitter or NAT/firewall problems.
No upper limit for the number of concurrent users should exist.
The system should be able to cope with flash-crowds and may be improved by additional
super-peers provided by content or service provider.
In the case of considerable network asymmetry, suitable compensation should be
provided by caching or super-peers.
Appropriate caching should be provided in case of content tails, e.g. in order to offer
infrequent content pieces or partial streams.
Client-site caching of P2P packets on a designated area of the device hard disk should be
considered to complement usefully the ISP-level cache.
Continuity of service should be ensured in case of situational breakdowns, peer failures or
opt-outs, change of IP numbers and network mobility as well as temporary packet losses.
In order to maintain adequate service continuity, it may be occasionally necessary to
switch to a reduced bitrate stream (for the same service). This should be performed
automatically. In such a case the service providers should generate a range of different
stream qualities (bitrates) or suitably encode the video streams in some form of scalable
video coding and/or multiple description coding.
Under extremely severe circumstances a fallback to Unicast streaming may be required.
A fast service build-up is required especially for live streaming.
Latency/switching time of P2P-based live streaming should be comparable to the DVBIPTV standards.
P2P may be complemented or combined in some cases by IP Multicasting or CDN
approaches. In the former case, if no IP Multicast is available, the client switches to P2P
based distribution12.
Ability to seek and resume playback at any position within a P2P-based VoD stream should
be provided.
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Social networks and user preferences
The P2P system should enable the implementation of social network functionalities
such as
on-line communities, friends, friends-of-friends
rating the content and usage preferences of the user
user personalisation
user comments and tagging
reputations and recommendations
If not desirable (e.g. for some specific TV channels), it should be possible to restrict or
deactivate (wholly or partially) the social network functionalities, either temporarily or
Content formats
Content providers should support audio and video streaming and file as well as associated
container formats that are customary and predominantly used in the Internet
environment. If possible, these formats should be compatible with those used in
conventional digital broadcasting such as DVB.
Content formats used by content providers and implemented in the P2P CE devices should
be aligned in terms of codecs, levels and profiles used.
Carriage of large files (e.g. HDTV) should be enabled for on-demand services.
Content delivery
Content should be delivered in the form of
live streaming of TV/radio channels,
on-demand file downloading (incl. subscription based content as podcasts),
on-demand progressive downloading.
Content may originate from any content sources including traditional broadcasting
sources, industrial content providers as well as general users (user-generated content).
Effort should be made to preserve high end-to-end content quality, with minimal
impairments and degradations of the original content.
Every means should be taken in order to minimise computational capacity in the CE P2P
device and to allow simple recomposition of partial P2P streams, regardless of the
transport system used (either conventional MPEG TS or direct A/V streaming over RTP).
In case of P2P-based forwarding, the FTA-content must be reconstructed after reception
in an unchanged manner and completely in terms of quality and transported
Copy management such as defined by DVB CPCM should cover usage restrictions after
acquisition of the content, in response to either simple signalling or Digital Rights
Management (DRM) information delivered alongside the content. A minimum requirement
would be central administration of content usage via P2P based unique identification of
this content (e.g. allocation to other peers’ upstream capacity by communicating their
current IP addresses).
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Access Services including subtitling, spoken subtitling, audio description, deaf signing may
be added to the core audio and video content, in order to provide value-added services
and satisfy requirements of different interest groups.
Watermarking services may be imbedded in the audio content, video content (or both), in
order to help differentiate our broadcast traffic from any illegal P2P traffic. In addition,
watermarking could help detect copyright information, authenticate users and monitor
content usage. Watermarking should not be perceptible to the user or otherwise degrade
end-to-end quality. It should be rugged enough to resist any functional or hostile
processing (e.g. attacks). Watermarking data protocol needs to be specified in order to
contain the required information.
Content acquisition
Content discovery and acquisition mechanisms in the P2P environments should be similar
or identical to those used in IPTV or open Internet TV services.
The P2P system should use efficient and easy-to-implement (‘lite’) content acquisition
mechanisms, suitable for discovery of both live and on-demand content. The system
should also be used to display service information. Announcements of Content on Demand
(CoD) files should be possible.
The P2P system may allow for a suitable display of RSS (Really Simple Syndication) feeds.
RSS allows publishing and frequently updating new content. This should be enabled on
clients for a browser-based display of feeds, user’s combination of different feeds and the
announcement of available content. If a browser doesn’t support subscription of a feed,
the final device should comprise an additional feed aggregator. Only versions RSS 2.0 and
higher should be taken into account. A broadcaster can choose RSS to transfer URLs (e.g.
of his own websites or torrents) to customers. RSS typically offer the options to subscribe,
which is valuable for broadcasters’ customer retention13.
A central server should be available for each service to check whether the content is the
same as labelled originally and thus provide authentication of the content and its
7.10 Service management and service monitoring
The P2P system should be designed to allow efficient service management performed by
the service/P2P provider.
The overall service quality and service experience should be controlled and monitored
constantly by the service and content providers. The network and traffic load
characteristics should be taken into account.
There should be a mechanism allowing the bandwidth usage shared by different
applications to be suitably prioritized by the user.
Statistics about audience tracking are to be available to content providers and service
The announcement of torrents by RSS is already known as ‘Broadcatching’ and realised by µTorrent, Miro player and
Vuze plug-in for RSS Feeds.
For example, each broadcaster could provide a Tracker-Server at an URI, such as ‘’ or otherwise
broadcasters could install a joint architecture.
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operators at any juncture (dynamically).
The P2P service should be interoperable with geolocation, DRM and other applications
required for fulfilling copyright and right management.
7.11 Management of P2P functions in a CE device
The P2P clients should be embedded in the CE device. They should be upgradeable
remotely by the service/network provider/CE manufacturer
The P2P client should require only a ‘moderate’ hardware footprint in order to comply
with the low cost nature of CE devices.
The P2P client should be transparent to different OSs, browsers and players
The P2P clients should be of modular design and future proof
Excessive usage of user’s upload capacity and user’s storage and processing power by the
P2P client should be prevented. Other applications should always be able to work in
conjunction with the P2P application.
The maximum upload capacity that is used should be adaptable (i.e. limited, automatically and
possibly also manually) as a function of the download capacity and the maximum available uploadbandwidth.
The P2P clients should be capable of being uniquely identified and authenticated
The P2P CE device should be able to work in passive (idle) mode comprising a wake-up
and a sleep function triggered by a P2P announcement and P2P-based transfer at
minimum CPU workload
The P2P CE device should have a simple user interface to install, operate and upgrade
The P2P CE device can be stand-alone or else can be integrated with IPTV, DTT, cable
and/or satellite receiving terminals.
7.12 Security issues
The P2P CE device provides a secure network connection to a known person (rather than
CE device)
The P2P system is able to combat eavesdropping and man-in-the-middle attacks
The P2P system contains the necessary content and network security mechanisms
including authentication, authorisation and accounting (AAA) mechanisms
The integrity and authenticity of content should be guaranteed by using the certificates
and trusted public key infrastructure (PKI). This can be achieved for the whole file and
the announcement (as a torrent). Each piece of a file can be checked using a lower level
of security comparable to hash sums. Note that hash sums cannot be calculated for live
streams in advance of broadcast, but pieces can be signed to verify their integrity and
authenticity at the time they are seeded to the P2P system.
7.13 Geolocation, DRM and storage-related issues
Broadcasters and content providers should be able to use the geolocation (GL, georestriction, geographical limitation) services in order to adhere to contractual obligations
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and target the contractually agreed footprint. The use of GL has no bearing on the design
of a CE device.
The delivery of content is most efficiently controlled at the first ‘server’ the P2P client
contacts, which can be either a tracker server for download or a resource-allocating
server for live streaming. At this central entity access to individual swarms/live streaming
topologies can be controlled and changed on-the-fly. The central metadata repository
should provide the possibility for broadcasters to adjust geolocation management
according to their transmission and copyright requirements.
CE devices with or without copy management or DRM will be available on the market to
support different business models. These devices should adhere to non-discriminatory
standardised solutions such as defined e.g. by DVB CPCM (but not limited to this solution).
The content provider or a broadcaster should be able to inject live streams and ondemand files via P2P networks and users should be able to record these. Access to these
streams and files should be controlled in order to allow or disallow redistribution or
remote access from/to the PVR over the Internet. Another control mechanism may be
required in order to provide services to the P2P network under additional conditions (for
example, up until, say, 7 days after live transmission).
Transmission of files and live streams across P2P networks to the general public should be
in the clear. After reception of such transmission, the content should remain in the clear
when stored for further redistribution via the P2P network, unless encryption is required
by the FTA content provider using e.g. the appropriate DVB signalling for FTA.
7.14 Network neutrality
Internet Service Providers (ISPs) should provide access to any legal content, including one
based on P2P delivery, indiscriminately.
Any traffic shaping leading to a degradation of service quality (including bandwidth,
packet-loss or jitter) compared to an average data transfer Quality of Service (QoS),
should not be tolerated.
The use of port filtering to deteriorate service quality of P2P-based FTA reception also is
not acceptable.
Existing commercial P2P services
Across the Internet, content can either be delivered as live (real-time) streaming or on-demand
content (files). Content can be of any type: audio, video, data or any combination of these.
Specifically, the most popular media applications and services in the Internet are the following:
Linear and on-demand radio over the Internet
Linear and on-demand television over the Internet
Interactive and personalized applications
Music downloads
Movie downloads
Media podcasting
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These services may lead to an improved relationship with our audiences and offer new revenue
The following is a collation of information provided by the most commonly encountered commercial
P2P systems.
[Editor’s Note: Statements made in the following section are contributions from the companies’
perspectives and may be of a promotional nature.]
Octoshape Streaming Solutions (, [7],[8],[9] delivers video and audio content
from studio to online audience. Octoshape's principal mission is to lower the costs and increase the
quality of live and on-demand streaming. Having created a P2P-based technology for streaming
audio and video, Octoshape wants to better the user experience of streaming content, while
cutting costs for the broadcasters. Using Octoshape grid-cast technology broadcasters can scale to
accommodate millions of concurrent users, and yet provide a quality media experience. Traditional
architectures transmit the whole stream directly from one server hosted by radio or TV stations.
With Octoshape, the end-user receives fragments of the live programme from many peers in the
grid. The result is a quality media experience, and a 97% reduction of bandwidth consumption.
Octoshape has been successfully providing live streaming services for the EBU’s Eurovision Song
Contest since 2005. In 2008 the EBU conducted a P2P Media Portal trial using Octoshape
technology. The company has recently partnered with content delivery networks (CDNs) Highwinds
Network Group Inc. and CDNetworks Co. Ltd. Its technology was chosen, along with the CDNetworks
CDN, to help deliver 2 Mbit/s video streams over the Seoul Broadcasting System (SBS) Website
during the Korean broadcaster's Olympics coverage. Turner’s is using Octoshape's P2P for
Live Feeds.
The main characteristics of the Octoshape P2P system are:
Cost-Effectiveness: Reducing price making live streaming profitable
No ‘server busy’: Having unlimited number of simultaneous viewers
No stream fall out: Using a multi fallback system
Compatibility: Using the leading media codecs and players
Statistics: Follow on-line number of users
Instant access: The stream starts in seconds
Reliability: Always a quality broadcast because the stream never stops
Freedom: Users can choose their preferred players
Availability: No more ‘server busy’ messages
Speed: ‘Plug-and-play’ using transparent integration technology
RawFlow,, is a provider of live P2P streaming technology that enables Internet
broadcasting of audio and video. RawFlow was incorporated in 2002. Its main office is in London,
UK. A P2P computer network relies on the computing power and bandwidth of the participants in
the network rather than concentrating it in a relatively low number of servers. When using this
technology, the bandwidth requirement of the broadcast is intelligently distributed over the entire
network of participants, instead of being centralized at the broadcast's origin; as the audience
grows so do the network resources available to distribute that broadcast without adding any
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additional bandwidth costs.
The RawFlow ICD (Intelligent Content Distribution) server provides the first contact point for clients
in the network. When initially installed, the ICD Server connects to the broadcaster’s existing
media server and begins receiving the stream, maintaining a buffer of stream data in memory at all
times. It then begins accepting connections from clients and serving them with the stream. When
launched by a user, the ICD Client first contacts the ICD Server and begins receiving the stream
from it. The media player plays the stream as it is received by the ICD Client. If it has available
resources, the ICD Client also accepts connections from other clients in the grid to which it may
relay a portion or the whole stream it receives as requested.
The ICD Client monitors the quality of the stream it is receiving and upon any reduction of quality
or loss of connection it again searches the grid for available resources while continuing to serve the
media player from its buffer. The buffer prevents interruption to the playback and ensures that the
end-user experience is not affected.
The ICD Server is always available as a last resort for clients that cannot find sufficient available
resources in the grid. This guarantees a constant seed of the stream.
RawFlow’s user-generated broadcast (UGB) technology offers a media platform which enables
individuals, brands and communities to easily produce live and on-demand digital broadcasts,
distribute them to multiple destinations simultaneously, engage with an audience through
multimedia communications, and monetize their brand. RawFlow provides the P2P distribution
technology for the Selfcast platform which went live in early 2007 and it has since then, attracted
thousands of broadcasters and millions of live viewers.
Selfcast is a free and easy-to-use service for anyone, and since its launch it has been used by very
diverse groups of broadcasters such as politicians, music events, sports clubs and Churches.
Selfcast utilises the basic functionalities of the UGB platform which include:
One-click broadcast
One-click recording
Widget technology
Embed functionality
Channel pages
High Quality encoding
Abacast,, is a commercial, quality Hybrid Content Distribution Network (CDN),
offering the content industry the ability to distribute and monetize live video, online radio
broadcasts, video-on-demand (VOD), games and software. It was established in 2000 and it is based
in the US.
It helps business models with revenue-generating features such as its Ad Injection System,
Subscription Systems or Synchronized Ads. It has efficient live and on-demand delivery options
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including standard Unicast, P2P or a Hybrid combination of both. It has the ability to monitor the
objectives with Understandable Analytics that are accurate, real-time and designed for business
and media people. Brand promotion and a superior end-user experience is provided with premier
and custom media players
Abacast provides the following services
Internet Television: End-to-end solutions for live broadcasts, video-on demand, advertising
integration, brand promotion and custom players.
On-line Radio: Abacast provides the solutions required to make online radio streaming
effective, legal, reportable and profitable.
Content Monetization: Video and radio monetization services including pre-roll
management, ad injection, banner ad sync and subscription management.
File delivery: Complete solutions for high-volume games, software, patch, and video
Education/Distance Learning: Archived or live course delivery services to anywhere on the
Corporate Communications: Enterprise solutions for corporate communications, sales
training, compliance and certification.
BitTorrent DNA
BitTorrent DNA™,, is a content delivery service that uses a secure, private,
managed peer network to power faster, more reliable, more efficient delivery of richer content.
BitTorrent DNA works with your existing CDN or origin servers, seamlessly accelerating your
downloads or HTTP media streams.
With over 160 million clients downloaded, BitTorrent is the consumer standard for software and
content distribution on the Internet. BitTorrent DNA extends the open BitTorrent protocol into a
managed platform for commercial-grade content delivery.
Founded in 2004, BitTorrent is a privately held company backed by venture capital firms, Accel and
DCM. The company is headquartered in San Francisco, California.
Peer Accelerated Content Delivery
BitTorrent DNA™ is the next step in the evolution of digital content delivery; it combines the
efficiency and organic scalability of peer networking with the control and reliability of a traditional
content delivery network (CDN). BitTorrent DNA™ uses one or more existing origin servers or CDNs
to seed a managed peer network. Use of the peer network is tightly controlled by a specialized
tracker operated by BitTorrent, Inc. and accessible to BitTorrent DNA™ customers through a webbased dashboard that provides control and reporting tools.
Assured Delivery
BitTorrent DNA™ is designed to complement existing delivery mechanisms, making the best use of
both peer and infrastructure resources. Customers using BitTorrent DNA™ for downloads may
associate with each object a quality of service (QoS) parameter that defines a required minimum
bitrate. When BitTorrent DNA™ is used for streaming media, QoS is set automatically to ensure
smooth playback with no buffering interruptions, while still making the most use of the peer
network. Throughout the download process, BitTorrent DNA™ carefully balances its use of peer and
CDN or server resources, downloading from all, in parallel, to meet per-object or streaming media
QoS requirements.
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Organic Scalability
By unobtrusively harnessing end-users’ unused network capacity, BitTorrent DNA™ scales organically
with demand, providing capacity exactly where and when you need it. Need delivery capacity in
some particular corner of the world? BitTorrent DNA™ will give you capacity there. Do you
occasionally experience unexpected spikes in demand that strain your delivery infrastructure?
BitTorrent DNA™ automatically scales its delivery capacity with demand to ensure a consistently
high-quality user experience.
Advanced Bandwidth Management
BitTorrent DNA™ runs quietly in the background with minimal impact to the end-user experience.
Our proprietary transport technology leverages the full available network capacity of all paths
without disrupting other applications. By detecting the presence of other applications, computers
and devices sharing the consumer’s broadband connection, BitTorrent DNA™ automatically
moderates its use of the network to ensure that web browsing, voice over IP (VoIP), Internet
gaming and other applications are not disrupted.
Friendly to Service Provider Networks
BitTorrent DNA™ contains a number of enhancements to mitigate the impact of peer networking on
service provider networks. These enhancements include: BitTorrent’s sophisticated congestionavoiding transport technology; an intelligent peer selection algorithm that prefers peers on the
same LAN, network or AS; and work with vendors of BitTorrent caching products to support local
cache discovery. By keeping traffic local and non-congestive, BitTorrent DNA™ reduces long-haul
and peering traffic for service providers, while improving the end-user experience.
Multi-CDN Acceleration
BitTorrent DNA™ is designed to complement existing delivery mechanisms, including content
delivery networks (CDNs) and traditional web servers. To provide maximum flexibility and
robustness, BitTorrent DNA™ can seed its managed peer network from multiple CDNs in parallel.
Multi-CDN Analytics
BitTorrent DNA™’s client-side telemetry and web-based dashboard provide performance visibility
across all deployed content delivery solutions, including third-party CDNs. With BitTorrent DNA™,
you see accurate reports of the actual performance experienced by your end users.
PPLive,, is arguably the largest P2P streaming video network worldwide. It was
created in December 2004 by Huazhong University of Science and Technology, People's Republic of
China. PPLive programmes are targeted at Chinese audiences. A majority of them are categorized
as movie, music, TV series or live TV streaming. Also available are some specialties covering sports,
news, game shows, etc. Most available programmes are in Mandarin, Cantonese or Korean. There is
also an increasing amount of programmes in English, such as Hollywood blockbuster movies and
popular American TV shows. All these English-speaking shows are hard-coded with Chinese
In addition to PPLive, many commercial P2P TV services have been developed recently in China:
TVants, TVUPlayer, PPLive, QQLive, Feidian, PPStream and SopCast). The majority of available
applications broadcast mainly Asian TV stations, with the exception of TVUPlayer, which carries a
number of North American stations including CBS, Spike TV and Fox News. Some applications
distribute TV channels without a legal license; this utilization of P2P technology is particularly
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popular to view channels that are either not available locally, or are only available by paid
subscription, as is the case for some sports channels.
Since the PPLive video stream depends on the network connection and numbers of peers,
occasional glitches such as short pauses during the viewing or re-buffering are not unusual. In some
circumstances, the stream may stop completely if the source video file crashes or not enough peers
are available to establish a smooth streaming.
A recent report by Jin Li of Microsoft [10] states that:
‘... current PPLive platform do[es] experience playback freeze for as long as 1 minute, and as
frequent as 4 freezing incidents in a 7 minute interval...PPLive also incurs a relatively long
playback lag. It is observed that PPLive can incur startup delay for about 20s to 30s for popular
channels, and up to 2 minutes delay for unpopular channels, and some peers may watch frames in
a channel minutes behind others’.
SwarmPlayer is being developed within the EC-funded P2P-Next project (see §18). It is based on the
BitTorrent protocol and allows a player to download movies, watch video-on-demand, and watch
live video streams using one technology, while taking advantage of the popularity and maturity of
existing BitTorrent clients.
The Project has completed the SwarmPlayer software development to support the above streaming
modes, but require an audience to test it on. After all, P2P technology is designed to support
thousands of users, and to properly test this, many users have to watch the same video at the same
In centralised video streaming systems, such as YouTube, a single set of computers provides the
video to all viewers. Such a solution requires a massive number of computers (as YouTube has) to
serve all of the videos to a large set of users.
Peer-to-peer technology takes a different approach. The video stream is served to a few users,
after which users exchange and forward the video stream among each other. The users thus help
serving the video, reducing or even removing the need for a central server park. Starting a
YouTube-like system becomes orders of magnitude cheaper when P2P technology is used. The
downside of peer-to-peer is that the quality is harder to control since the responsibility of
forwarding the video is shifted from the central server park to the users themselves. If the users
cannot or will not forward the video among each other, the quality of the system will suffer.
The goal of this trial is to examine how well SwarmPlugin scales when serving thousands of users on
the Internet. It is not possible to reproduce thousands of users around the globe in a lab, so the
P2P-Next project uses a trial network involving a large number of participants. It is hoped that in
return for their participation, participants will receive a glimpse of what the future of online video
might look like.
To understand how well streaming works with SwarmPlugin, statistics are being collected to
understand what is going on in the network. Also, when the video is finished, several experiments
are run, including a new NAT traversal mechanism, an ISP-friendly congestion control algorithm and
a novel UDP-based light P2P swarming core.
P2P-Next is developing a platform that takes Open Source development, open standards, and
future-proof iterative design as key design principles. By using P2P technology we aim to provide an
efficient and low-cost delivery platform for professional and user-created content.
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P2P Trials, Experiments and Experiences
Eurovision Song Contest
On 20 May 2006 the EBU performed a technical trial of live-streaming the Eurovision Song Contest
(ESC) using the Octoshape P2P system. The following are some of the statistical and operational
data obtained:
A maximum of 15000 concurrent streams were logged
There were more than 70000 unique users.
No congestion was experienced through downloading the Octoshape media player plug-in.
The MS Windows Media player was used.
3 quality levels were provided: 200 kbit/s (Q2CIF), 450 kbit/s (QCIF), 700 kbit/s (CIF)
There were no major technical problems and almost no complaints from users.
Network dependent quality – asymmetry was an issue.
Neither rights management (DRM) nor geolocation (geographical restrictions) were applied.
The EBU repeated the experiment with Octoshape for the Junior ESC’06 and ESC’07. For ESC'07 the
observed peak of concurrent streams was above 25000.
In May 2008, the Eurovision Song Contest was streamed live from Belgrade (Serbia) with the
following statistics:
More than 155000 unique visitors.
45000 concurrent streams.
338000 sessions.
Total 171000 viewing hours.
EBU Member Services
RTVE has been offering two TV channels in high quality with Octoshape since the summer of 2006.
RTVSLO has been offering a number of services provided by Octoshape for some time. Today
RTVSLO has 3 TV and 8 radio channels. All channels are in high quality.
RTP has been offering 1 TV channel in high quality with Octoshape since the beginning of 2007.
DW has been offering a high quality TV channel with Octoshape since 2006.
RNE has been offering three radio channels in high quality with Octoshape since 2006.
Many other Members are currently offering P2P live streaming in high quality. As such, high quality
P2P streaming may no longer be considered an experiment, but a ‘normal’ 24/7 service to the
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EBU Test at IBC 2006
As part of the ‘EBU Village’ stand at IBC 2006 (International Broadcast Convention, in Amsterdam)
the EBU presented a live P2P streaming demonstration. Figure 10 shows the equipment setup.
Figure 10: EBU demonstration of P2P distribution at IBC 2006
Three providers participated in this demonstration, RawFlow (in association with CacheLogic),
Abacast and Tribler (TUD). Octoshape had been invited to participate, but it decided not to do so.
Each provider was fed by content served from the EBU Stream Farm in Geneva. Three stream
channels and one file repository were set up:
IBC Daily News: a daily news programme of about 15 minutes length, produced by the IBC. A
compressed version was sent to the Geneva servers over a secure connection and the programme
was streamed in a loop all day at 800 kbit/s.
EBU HQ: a palette of programmes produced by the EBU at high bitrate (800 kbit/s).
EBU: a live stream showing the Eurovision PNN contribution news channel.
Velocix: the IBC daily file was sent to Cachelogic so that it was available for fast download in DVDlike quality using a P2P BitTorrent client such as Vuze. An attempt to produce an iPOD-compatible
version in MPEG-4 failed because no software could be identified that ensured lip-sync after the
conversion (several seconds of delay were observed with Imtoo, Cucusoft and Videora).
Five laptops were available to receive the streams and files on the P2P booth from the different
providers. A sniffing software (NetLimiter) was used to monitor IP packets being received or sent by
the individual laptops (or from a central server).
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Prix Europa 2006 concert
The Prix Europa 2006 opening concert was given on 14
October 2006 in Berlin by a Portuguese World Music
group called Gaiteros de Lisboa. On the occasion of
this one-hour long concert, the EBU organized a
technical experiment to distribute multichannel 5.1
audio. The main purpose of the experiment was to
integrate a multichannel HE AAC real-time encoded
sound programme with an Octoshape P2P streaming
server and then provide it as a webcast across the
Internet. Many who listened to the webcast were
impressed by the high quality and smoothness (no
interruptions) of the sound delivered. On the
downside, however, the number of users of the
webcast was unimpressive.
Number of unique users: 52;
Number of sessions: 914;
Number of different countries: 13;
Average session duration: 10 min 44 sec;
Peak number of users: 11.
The experiment was significant because for the first
time an event was ‘broadcast’ live in 5.1 multichannel
audio across the Internet, proving its potential to
address large audiences with high-quality surround
Figure 11: P2P experiment
at the Prix Europa 2006
WDR evaluations of PPLive and TVants
The following outlines the results obtained when testing the functionality of the PPLive and TVants
P2P live streaming systems at WDR, Cologne in 2006. PPLive and TVants are Chinese IPTV
applications based on P2P. In their native markets, the video content that they distribute stems
from channels such as CCTV 5 and Shanghai Sports, but also the BBC and in part, premium content
such as the English Premier League football. Further special sport events such as the FIFA World
Cup or the Olympic Games are also streamed live by PPLive and TVants. According to its own
account PPLive had up to 500000 simultaneous users and the software was downloaded over 20
million times. Whilst the RealVideo codec only works with PPLive, both systems support Windows
Media encoded streams using bandwidths of typically 200 – 400 kbit/s, which is commensurate with
the typical upstream capacities of broadband users.
Users of PPLive receive an update channel list from the central PPLive channel list server. After
selecting a channel the user asks root servers to retrieve online peers for this channel. Peers
augment this list by sending their own actual lists of peers, so the content chunks can be shared
with each other. The TV engine is responsible for downloading the content chunks and streaming
the video to the local video player. Two buffers exist within local player memory; the PPlive TV
engine buffer and the media player buffer. While a media player buffer is commonplace for
streaming, the PPlive engine buffer provides an efficient forwarding of content–chunks to peers.
TVants is similar to PPlive but contains more features for analysis such as monitoring network
activity, a graphical display of the buffer level and an event list. A search function allows finding
specific channels. Furthermore the numbers of trackers and seeders, the shutdown and build-up of
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connections can be displayed. Figure 12 shows the TVants stream of the FIFA World Cup game
between Italy and the Czech Republic.
Figure 12: Screenshot of the TVants live stream of the FIFA World Cup
Danish Broadcasting corporation P2P trials using RawFlow and
Trial with RawFlow during 2005-2007
From March 2005 to December 2007, DR performed a live trial with 3 Internet radio services from RawFlow was selected mainly because of better user-experience and easy integration
with DR’s HTML player. The trial was a parallel test where users had the option to use P2P or
choose the normal stream.
There were three radio streams available; music and journalism, jazz (music only) and soft (music
only). The format used was MS Windows Media Audio at 32, 64 and 96 kbit/s
Figure 13: Player integration, install RawFlow ActiveX plugin
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Results of the trial:
Simple player integration
Simple server setup
100% server uptime
Easy install and transparent for the users
90% end-user acceptance
5000 users peak (programme 3, 150000 unique/month)
Close to 1 million client downloads (2007)
DR saved 70-80% bandwidth from P2P
Figure 14: RawFlow reporting tool, 1 day view,
red=P2P traffic, Blue=normal traffic, green=savings in%
Trial with Octoshape during UEFA 2007
The trial consisted of a live TV simulcast of the UEFA Cup in May 2007. Two of the semi-finals were
streamed on the Internet only, whilst the final was simulcast on TV and the Internet. The format
used was MS Windows Media Video at 1.3 Mbit/s.
Results of the trial:
Easy to setup encoder
Total 1700 users
Peak ~ 1000 users
Fast start and stable streaming
DR saved about 60% bandwidth
Figure 15: DR’s Octoshape UEFA 2007 test
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EBU P2P Media Portal
The trial on the ‘EBU P2P Media Portal’ (‘EBUP2P’ for short) was set up by EBU Project Group
D/P2P (Peer-to-Peer) in autumn 2007 in order to perform technical evaluations of the P2P (Peer-toPeer) technology provided by Octoshape. The EBU may choose to set up a one-stop Internet
platform on the EBU home page,, through which any Members' television and radio
channels may be made available to the general public worldwide using a broadband (WiFi)
connection and a personal computer.
Figure 16: EBU P2P Media Portal interface GUI
The EBUP2P was designed to become a unique shop window for EBU Member organisations, showing
their creative efforts and potentially forging their public broadcasting mission identity
internationally. All active (and associate) EBU Member organisations could join the EBUP2P with
their national, regional and local channels, both radio and television.
The principal conclusions of this trial can be summarized as follows:
EBUP2P represented the state-of-the-art technical solution and fulfilled all technical and
operational requirements in terms of the service quality, scalability, video and audio
quality, accessibility, security and user-friendliness,
EBUP2P had no technical limitations regarding the number of channels to be accommodated
in the Portal, Members could flexibly join in and opt out at any time,
EBUP2P fulfilled our requirements concerning copyright, by applying territorial filtering
(geolocation) and watermarking,
EBUP2P enabled a number of business models,
EBUP2P was at the time the most efficient commercial proposition for media distribution
over the Internet.
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Table 5: EBU P2P channels (2007)
Hessischer Rundfunk (HR)
Deutsche Welle (DW)
RTV Slovenia (RTVSLO)
RTV Slovenia (RTVSLO)
24H tve
RTV Spain (RTVE)
DOCU tve
RTV Spain (RTVE)
TV Ciencia on-line
TV Portugal
Polish TV (TVP)
Taiwan TV
radio-suisse jazz
radio-suisse pop
radio 3
radio classica
Val 202
EBU’s Tribler experiences
Several EBU Member organizations have been testing the open-source Tribler P2P system developed
by numerous universities and coordinated by the Technical University Delft. Tribler is a social
community that facilitates sharing through a P2P network.
When the Tribler application program is started it will automatically start searching other users
that have Tribler running on their computer. When a connection is established it starts exchanging
information. First it exchanges personal information (such as your avatar picture, your friends list,
download history, etc.) and information about files that are available in the network. These files
can be personal, shared files, but also files that have been received from another person.
Figure 18: Tribler screenshot
The information about the discovered files and persons is available in the Tribler program. By
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browsing through the files and persons each user can find their preferred files and users. The
Tribler program helps you by giving extra information about each item (whether it is a file or a
person) and also shows what other users think about it. When you find a person you like, you can
add him/her as a friend. Any file which you find interesting can be downloaded and will be
available in your library.
In early 2009, Tribler was the only Open Source environment that supported all three modes of
Download the video and watch it afterwards (typical BitTorrent behaviour)
Live real-time streaming (web-cams, live TV broadcasts, etc)
Two EU Framework Programme 7 projects, with a combined budget of 26.26€ million are actively
extending the Tribler foundation in the 2008-2013 timeframe. The first project, called P2P-Next, is
developing a platform that takes as key design principles Open Source development, open
standards and future-proof iterative design. By using P2P technology, P2P-Next aims to provide an
efficient and low-cost delivery platform for professional and user-created content. It is focused on
crafting a production-level Open Source reference implementation of ‘next-generation P2P
technology’. During Q3 of 2008 P2P-Next held a large public trial with 85,000 participants. This
successfully tested the first unified P2P algorithm supporting live streaming, on-demand viewing,
and HDTV download. Quality of Experience was measured to be very high with nearly no frame
drops and video initialisation delays of the order of seconds.
IBC 2008 and IBC 2009 – P2P-Next trial using a Pioneer set-top-box
During the IBC 2008 in Amsterdam, the P2P-Next Project released its first version of NextShare, an
Open Source P2P video delivery platform. NextShareTV is a STB (Set-Top-Box) implementation of
the NextShare content delivery platform running on low-cost embedded hardware.
The P2P-Next project successfully released and tested the first Beta version of their P2P live
streaming technology. This new technology allows broadcasting a live stream, such as a TV channel
or webcam feed, to potentially millions of Internet users. Key is the bandwidth efficiency of this
technology, by expanding the proven BitTorrent protocol you can stream to thousands of people
using roughly the same amount of bandwidth as for a single user. This platform may enable large
audiences to stream and interact with live and on-demand (VoD) content via a set top box or a TV
receiver. In addition, it may allow audiences to build communities around their favourite content
via a fully personalized system.
Figure 17: EBU P2P-Next demonstration team at IBC 2009
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The harnessing of open source P2P video streaming technology like NextShare by low-cost consumer
electronic devices represents a change and an exciting opportunity for the market. The next step is
to agree Open Standards for interoperability between CE peer devices across Europe.
The P2P trial at the IBC 2008 was the world's first end-to-end streaming of live TV via a P2P
network to a set top box using professional content at professional quality.
P2P Social Networks
One of the underlying principles of any P2P system is the participation of several peers in a
common activity (for example, sharing a video clip). This topic is currently the subject of many
studies and considerations. P2P social networks could potentially facilitate the introduction of
several social features in content distribution, as follows:
communication primitives
strong peer authentication
strong content integrity checks
permanent storage of context
semantic clustering
Intuitive usage/insertion of own content, no matter which source type, codec etc (ingest
should be profiled to align with standards – thereby enabling horizontal market integration)
feedback and rating to myself as content creator, as well as feedback and rating to the
support for time-shifted-viewing, realized via a buffer or the ‘swarm’ itself as a buffer
metadata, like ratings, tags, recommendation lists, social preferences
community tagged browsing accessible and changeable/expansible by the users.
Social networking web sites, which allow users to create identities and link them to friends who
have also created identities, are highly popular. Systems such as Facebook and MySpace utilize a
traditional client-server approach to achieve this, which means that all identities and their social
links (the entire social network) are stored and administered on central servers. Although this
approach supports highly mobile user access - users can log-in from any computer - it also poses
high dependence on predefined central server(s), which results in possible exploitation of private
data. An alternative approach is presented in a paper produced by the Delft Technical University
(TUD) [11]. This TUD protocol is based on a gossip (or epidemic) protocol, which uses a completely
decentralized peer-to-peer system to create and store the social network information. The system
is self-administered and works in a highly transient environment of peer availability. The design and
implementation of a distributed social networking system is scalable and robust, allowing users to
perform core social networking functions of establishing and removing social links without any
requirement for centralized servers or administration.
10.1 Free-riding issue
The problem of free-riding arises if some peers in the P2P network do not forward the video
content to other users [12]. A free-rider in a P2P network is a peer that consumes more resources
(or downloads data) than it contributes (or it uploads little or nothing). The burden of uploading
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falls on a server and/or on some altruistic peers (but the latter may be too few to provide all peers
with an acceptable quality of service). Consequently, the whole P2P network may suffer. Several
solutions to motivate peers to contribute upload capacity have been proposed. In Give-to-Get
(G2G), peers have to forward (give) the chunks of content received from a peer to others in order
to get more chunks from that peer. By preferring to serve good forwarders, free-riders are
excluded in favour of well-behaved peers. When bandwidth in the P2P system becomes scarce, the
free-riders will experience a drop in their quality of service. Free-riders will be able to obtain video
data only if there is spare capacity in the P2P system. G2G has been implemented by the TUD in
Delft for VoD services using any video codec. The system splits the video stream into chunks of
fixed size, which need to be played at a constant bit rate.
An important indicator of the peer’s ‘reputation’ is the sharing ratio, i.e. the ratio of upload and
download capacity over a given time period. Popular closed BitTorrent trackers such as require a set minimum sharing ratio for a peer to stay in the system and ban
peers that upload content of low quality or spam. However, these trackers make use of a
centralised management authority which arbitrates among peers. A fully distributed system for
reputation management has been developed and deployed in the open source file sharing network
Tribler by the Delft University (TUD). This decentralised protocol is called BarterCast [13]; the realtime upload and download statistics are broadcast to all peers. Each peer calculates its own
reputation based on their local traffic information. The spreading of false and misleading
information is minimised by applying the maxflow algorithm in computing indirect contributions of
one peer to another peer.
Incentive mechanisms are essential components of P2P systems as they enforce peers to share their
resources and participate. Recent P2P systems that distribute live media streams take their
inspirations from BitTorrent which is more focused on sharing of files. Studies have shown that BT
incentive mechanisms which may be suitable for file sharing are not well suited to streaming live
media. To this end, new incentive mechanisms specifically designed for continuous media such as
live streaming are required [14].
10.2 User data and privacy issues
In considering P2P-driven social networks it is critical to preserve user privacy versus sustainable
advertisement-driven business models. On the one hand, many consumers would not like their past
history of downloads being recorded and/or disseminated to whole of the network; on the other
hand, many would like more personalisation of search results and recommendations. The latter
case is similar and relevant to the scenario of targeted advertisements, where sponsors target a
particular audience based on their past preferences (such as Amazon) and/or search keywords
(Google's ‘Sponsored Links’).
With most online social networks, users are invited, at the time of registration or first usage, to fill
out social features such as ‘My Favourites’. Typical fields (in addition to optional personal data
such as age, gender) are: movie-actors, music bands, brand names, books, colours, dream holiday
destinations, movies, TV series and football teams.
This provides more dense connections among users, and using this information, similarity and
correlation among them can be established despite having little or no history of download
preferences. This thereby helps alleviate the above two sub-problems. A topic requiring further
research is whether the free-to-air/Internet business model can work when users fill in their
profiles, even in the absence of recording their history?
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Consumer Electronics
11.1 P2P-enabled Devices
A number of CE products capable of receiving television services via the Internet have recently
appeared on the market, and many more have been announced by the major CE vendors. Products
include televisions, games consoles, set top boxes and PVRs. It is likely that many more types of
device will become connected in the coming years.
It is assumed that Internet TV services will be adapted from the current versions intended for PCs
to better suit consumer electronics devices. This will include both adaptation of the service front
end to provide a suitable ‘3 metre’ user interface; and possibly technical changes such as different
codecs and security schemes to match the capabilities of CE products.
11.2 Implications of P2P for CE Devices
Compared to an Internet TV-enabled CE product implementing ‘conventional’ delivery protocols,
the following additions or changes are required to enable P2P protocols:
An implementation of the P2P client, including protocols and control
Integration with browser and/or embedded applications (such as EPG)
Ability to execute a global search for content to be consumed, that spans multiple content
providers and service provider networks, and in addition spans all the content on
cooperating device types (PC, STB, Mobile, Console)
Sufficient storage internal or external storage for the P2P cache. This may already be
present if the device is a PVR
Sufficient CPU and memory resources to run the P2P client in parallel with other television
functions, without impairing the user experience
Possibly a graphical user interface to allow users to configure any necessary P2P-related
settings and provide information such as uplink bandwidth usage, share ratios, etc.
In general, the larger the number of peers available, the more efficiently the P2P network will
operate. Users may also gain some ‘status’ within an online community based on the amount of
bandwidth they contribute to the P2P network. This could imply that the device should continue to
function as a peer in the network while in ‘standby’ mode. However, this is in conflict with the
trend in the CE industry to reduce power consumption of devices for environmental reasons. For
example, Philips 2008 range of large LCD televisions has a standby power consumption of 0.15W
[15]. The power required to run a P2P client in the device, including CPU, storage and network
interface would far exceed this figure. If such a feature was present on millions of devices, the
increase in overall power consumption would be significant, and may well attract the attention of
11.3 Motivation for CE vendors to build P2P Enabled Devices
The business model behind the manufacture of consumer electronics devices can very roughly be
divided into two categories.
‘Horizontal’ market products, not tied to any particular service provider and sold in retail.
These products typically implement open standards and in some limited cases proprietary
components that are de-facto standards. This enables them to receive services from many
‘Vertical’ market products, distributed by a service provider; typically subsidised by the
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provider and only capable of receiving services from that provider.
The motivation to include a P2P client in a CE product will depend on the business model. The
following sections discuss the conditions for P2P clients being added to Internet TV products in
horizontal and vertical markets. It should be noted that many variations of these business models
are possible and are likely to emerge. Time will tell which will be successful.
11.3.1 Horizontal Market Products
In a ‘horizontal’ market, the manufacturer’s interest is to make attractive products that users will
want to buy, and to maximize the profit realised from selling these products.
In order to make a product attractive, it should be able to access a wide range of services including
the most popular services for the market in which the product is sold. It should be easy to use the
product to access the services and the quality of the pictures and sound should be as high as
An important factor in maximising the profit for the manufacturer is that the product must be sold
in as many markets as possible. Variations between models for individual countries are very
expensive for manufacturers. Indeed, it is often not viable to develop and sell products that are
specific to a single country, meaning that such products may simply not emerge.
The likely conditions for P2P clients appearing in horizontal markets are as follows:
The P2P client must provide access to a wide range of services that would not otherwise be
available, or at least access to the most important, popular services in particular markets.
The P2P client must be applicable across multiple markets. In Europe, this means the same
P2P client should be capable of receiving relevant services in many countries.
The client side P2P protocols must be stable, so that the product does not require long term
after-sales support. In general, the business models behind horizontal market CE products
do not allow ongoing upgrade of products in the field. Note that this may change if there is
some revenue stream to the CE vendor after the product has been sold, for example from
services provided by the CE vendor or revenue sharing of paid-for services. Of course, only
software upgrades are possible in the field – any requirements for new hardware cannot be
It is strongly preferred that a single open standard emerges for the client-side interface to
the P2P system. This greatly increases the chances of the above conditions being met, and
in addition, openly standardised interfaces prevent lock-in by particular companies to their
specific client (and indeed server) implementations. Such lock-in to a single source of
components may not be acceptable to CE vendors.
11.3.2 Vertical Market Products
In a ‘vertical’ market, products are a part of a specific provider’s service offering, and are usually
manufactured to that provider’s specification. The use of proprietary components or components
not widely used by other providers is feasible. Indeed, features not available from other service
providers may be an important differentiator for a vertical operator compared to their competitors.
However, vertical markets can also benefit from, and even be enabled by, standardisation. This is
especially true for components that are not differentiators between vertical operators, as has been
the case for content delivery protocols in the past. Where an open standard exists and is widely
used, implementations become commodities available from multiple sources, or even as open
source software. This reduces costs for the operator, avoids proprietary lock-in and ultimately
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leads to greater levels of penetration for the technology concerned, which benefits all
11.4 Internet TV Products
Below are some examples of existing and announced CE products with Internet TV features.
Game consoles including Sony Playstation 3, Nintendo Wii and Microsoft X-Box 360. These
products are all capable of receiving Internet TV services. Currently all are to a large degree
‘vertical’ in their nature, as the services available are controlled by the manufacturer and
are made available with that manufacturer’s branding. Software updates are regularly
provided by the manufacturer, often adding new features. These are funded through sales of
games (which include a licensing fee) and from revenue derived by the manufacturer from
services offered. It is not believed that the consoles include P2P clients at present, but it
should be possible to add them in the future via a software update, as the devices are very
powerful and include storage.
Philips Net TV – televisions including Internet TV features. A Services Portal will be provided
by Philips, offering the user facilities for finding suitable services and content. Services and
content will be available from multiple providers. Once the user has navigated away from
the Portal, they interact directly with the service provider and content is distributed using
that service provider’s infrastructure. Services are browser based so branding is under the
control of each service provider.
AcTVila – a standard for Internet TV from CE products in Japan, based around a common
Portal run by several CE vendors.
Telecom Views on P2P Distribution Systems and Services
12.1 Business Opportunities
Beside conventional IP Multicast and Unicast systems, P2P systems may offer new options for
enhancing content delivery systems provided by Telcos15.
Whereas IP Multicast provide high bandwidth efficiency and scalability within a single Multicast
domain and CDNs are well established systems with a predictable and high QoS up to a distinct
number of customers, P2P systems are simple to deploy, they do not need specific network
provisioning and, in principle, scale gracefully with number of viewers.
It is necessary to point out that the P2P service providers have generally adopted a different
business model than the traditional Telcos. In contrast to the traditional client-server applications,
where communication is to and from a central server, P2P applications comprise peers that serve
simultaneously as clients and servers.
P2P technology enables new traffic-intensive services with minimal infrastructure and seamless
scalability and may helping transform Internet users from information-consumers to producers and
The dominance of P2P applications in the Internet traffic is stimulating broadband demand and
creating a huge market potential for Telcos for the next years, but straining the current business
model of Telcos on the other hand. Telcos want to increase operational efficiency and service
quality while reducing costs, improve customer satisfaction and introduce new innovative services
Telco is an abbreviation for Telecommunications Company
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beyond pure bit-transport.
12.2 Challenges for Telcos
The emergence of P2P is posing significant new challenges to achieving efficient and fair utilization
of network resources.
P2P systems build independent overlay topologies on the existing network infrastructure
whose traffic cannot be easily controlled by Telco’s traffic engineering
Increase in P2P related traffic does not translate to additional revenues for Telcos due to
‘all-you-can-eat’ flat pricing
Potential congestion due to unexpected traffic peaks in some network areas leads to
customer dissatisfaction and forces Telcos to invest in significant infrastructure updates
without getting additional revenue streams
50-70% of P2P traffic flows to destinations outside the single ISP network, leading to high
inter-ISP peering costs.
Presently, little or no direct communication and coordination between Telcos as network providers
and P2P service providers takes place. Consequently, network resources are used inefficiently and
P2P applications do not take into account the existing network topology. In particular:
P2P nodes connect to neighbours randomly, irrespective of underlying network topology
P2P causes a large amount of cross-ISP traffic and bottlenecks in traffic routing, leading to
inefficiencies, and consequently both ISP and customers suffer.
12.3 ISP- P2P Collaboration
An improved collaboration between ISPs and P2P systems will certainly increase the overall system
performance for ISPs as well as P2P systems aiming to decrease backbone traffic and bring down
network operation costs by enabling service providers to communicate information about network
conditions to client applications for the purpose of facilitating improved P2P traffic performance.
Instead of selecting peers at random without exact knowledge of the underlying network topology,
ISP- P2P collaboration can align P2P system topology with the Telco’s network topology, reducing
cross-ISP traffic and ISP peering costs, as well as improving P2P application performance.
Telcos can use P2P systems for optimized content-delivery networks (CDNs).
Different systems for ISP-P2P collaboration are under development such as:
P4P activity conducted by DCIA (Distributed Computing Industry Association), see
OnO activity by AquaLab Project, see
Peer Mapping Service activity provided by TU-Berlin/Deutsche Telekom Laboratories, see
SmoothIT FP7 project, see §18 of this report.
The IETF started to standardizes an ISP-P2P collaboration solution in a new ALTO (Application-Layer
Traffic Optimization) group. See
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12.4 Integration of P2P Client at Customer Premises Equipment
In addition to the network related components (content ingest, content management and control,
network caches), P2P clients located at the customer side (home network) are an essential part of
P2P based content delivery systems provided by Telcos.
There are three main options to integrate a P2P client into existing in-home components, each
having its advantages and disadvantages:
12.4.1 Option 1: P2P-TV Client on STB
P2P TV Client is located at STB which is connected directly via Home Gateway to P2P
All CDN/P2P related traffic (management & control, streaming content) should be routed to
the STB via the Home Gateway and In-home Network
Extended effort to assure Quality of Experience (QoE) necessary
STB should be equipped with sufficient computing power and storage to host and run the
P2P TV Client
P2P Client and Home Gateway have to deal with Firewall/NAT issues of CDN/P2P solutions,
especially inbound connections are an issue
In-home Network shall provide direct access to P2P-Client at the STB for Management &
Control by the service provider (not in the case of certain horizontal market deployments)
Collaboration between service and network provider can enhance QoE
12.4.2 Option 2: P2P-TV Client on PC
P2P TV Client is located at PC which is connected directly via Home Gateway to P2P network
This is current state-of-the-art solution, nearly all available CDN/P2P solution support
this approach
Several solutions offer P2P client as Browser Plug-in but more commonly P2P Client as
separate software application
Customer needs to install P2P client software at her/his PC
All CDN/P2P related traffic (management & control, streaming content) should be routed to
the STB via the Home Gateway and In-home Network
Extended effort to assure Quality of Experience (QoE).
P2P Client and Home Gateway have to deal with Firewall/NAT issues of CDN/P2P solutions,
especially in-bound connections are an issue
In-home Network shall provide direct access to P2P-Client at the STB for Management &
Control by the service provider
12.4.3 Option 3: P2P-TV Client on Gateway and STB
P2P TV Client functionality is distributed, between Home Gateway and STB
All CDN/P2P related traffic (management & control, streaming content) is terminated on
the Home Gateway
Home Gateway also hosts storage for content buffering and a streaming server (UPnP
media server) to deliver a content stream in the home network
Based on UPnP-AV algorithm a media renderer running on the STB can access the content
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provided by the media server decode and replay it
All CDN/P2P related traffic from/to open Internet is decoupled from Home network
No P2P management & control traffic is transmitted in the home network
Firewall/NAT issues of CDN/P2P solutions can be avoided
Service provider can access and manage the P2P-Client directly without user interaction
No specific software is needed for STB – current DLNA enabled STBs can be used in principle
Home Gateway needs additional computing power and storage to host P2P – client
Table 5 is a comparison of the three optional approaches described above.
Table 5: Comparison of the different approaches
P2P-TV Client on STB
Compact solution
Hardware and Software
requirements nearly met with
current STB already - effort for
integration is limited
P2P-TV Client on PC
Compact and well established
Hardware and Software
requirements also met with less
powerful PCs
Approach already addressed by
several solution providers
Standardization activities
Standardization activities
Streaming to additional devices
based on known technologies
P2P TV Client on Home
Gateway / STB
Direct access to Gateway
including P2P-Client facilitate
complete service management
for ISPs
Decoupling Internet traffic and
In-home Network traffic
Better Support for QoE only
media streaming traffic in the
home network; no P2P control
Firewall/NAT issues easier to
In principle all Streaming client
enabled devices can be
Complete P2P control traffic
should be routed through home
network (QoS issues)
PC is not target Device for the
living room
Control of P2P client in the
home network more difficult
Complete P2P control traffic
should be routed through home
network (QoS issues)
No complete solution for
Firewall/NAT issues available
Control of P2P client in the
home network more difficult
No support for streaming to
additional in-home devices
No complete solution for
Firewall/NAT issues
New Home Gateways with
enhanced functionality
necessary (enhanced Hard- and
Software Requirements)
Currently approach not
addressed by solution and
service provider
No support for streaming to
additional in-home streaming
client devices
P2P-related Geolocation Systems
A geo-restriction (geolocation) system allows delimiting geographically multimedia delivery over
the Internet, so that end users could access the media only within pre-determined areas, such as
national territory or the EBU Broadcasting Zone. Geo-restriction services are achieved by making
use of the assignment of IP addresses to a geographic location. The IP address ranges are assigned
by the Internet Assigned Numbers Authority (IANA) and its regional assignment agencies. This
identification can be improved by means of checking the browser time, browser language, version,
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The use of GL services may facilitate the successful resolution of webcasting rights issues and may
be helpful in EBU negotiations with the various sports federations. Using P2P based Live-Streaming
and (Progressive) Downloading, access to content offered by the broadcaster can be administrated
by identifying the geographic position of the requesting user. This control can obviously be best
achieved by a central entity.
The GL system chosen must satisfy some minimal technical and operational requirements. Those
agreed by the EBU members are given below
13.1 Accuracy
While the accuracy of a decision based only on a single criterion as the IP address is often not
accurate enough, the probability of a correct determination of location is increased by combining it
with the evaluation of the language version of the accessing browser and media player, the time
zone etc. Generally accuracy thus is a property of the GL system that qualifies how successful the
determination of the end user's location is. For national and supranational level accuracies of 99%
or more are offered, while values of 95% are often accepted by right owners (except for premium
The technical notion of accuracy includes detection of both false positives and wrong negatives. It
includes reproducibility and consistency of the results. Unfortunately the numbers given for
accuracy usually do not specify the number of wrong negatives, which could be problematic for the
public remit of broadcasters.
13.2 Robustness
A GL system should be able to withstand stress such as when heavy traffic is experienced as a result
of concurrent requests.
13.3 Security
A GL system should disallow any illegal or illicit usage (e.g. hackers). Visitors with unknown
addresses (anonymous visitors) should be rejected, redirected and given a pop-up caption. Visitors
who may attempt to access the media on the Member’s site via known or unknown proxies should
be disallowed access. To this end, the GL system should be able to identify all known and emerging
proxies as well as anonymizers and put them in the « blocking area ».
13.4 Secure connection
A certified secure mechanism has to be included in the connection to the stream server. The
security solution proposed should be standardized as an open standard and be proven.
13.5 Server side components
There should be no executable or server components that would need to be installed on each
server. The script needed should be part of the HTML page.
13.6 Interoperability
The GL system shall be interoperable with any operational platforms used by EBU Members
including Windows, Solaris and Linux and including the different types of streaming servers (e.g.
Windows Media, RealNetworks, QuickTime). Furthermore the GL system architecture should allow
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one or several instances of the GL database running on one or several servers, as required. Upon
registering these databases, the load should be spread in a uniform way among these instances.
13.7 Flexibility of coverage
The coverage of the allowable GL area should be flexibly modifiable by each EBU Member in order
to suit its specific requirements on an event-by-event basis:
National borders
Part of the country (e.g. German Länder)
Group of countries (e.g. common-language countries)
Pan-European coverage
European Broadcasting Zone (including, optionally, some additional countries)
13.8 End User Access
The end user should be able to access the streaming media published by an EBU Member only via
the Member’s web site by clicking on a corresponding hyperlink. Direct access through the media
player by cutting-and-pasting the URL should not be possible.
P2P-related Metadata
Content distributed in a P2P environment needs to be described by a suitable metadata
specification. At the time of writing this document, there is no internationally agreed P2P-related
metadata standard. The closest to such a standard is a proposed P2P-Next Rich Metadata
Specification [16].
The P2P-Next Rich Metadata specification provides a minimum set of attributes which are necessary
to describe a content item in the Next-Share system.
This Specification consists of the mandatory Core and Optional metadata. Splitting the metadata in
Core and Optional metadata provides flexibility to adjust the metadata system to any business
model that may be utilized for the content item.
The Core metadata contain only those attributes that are essential for all business models and that
do not change over the course of time. The Core metadata is packetized together with the actual
media content and the hash values for the .torrent-file are created based on this package.
In addition to Core metadata, several types of Optional metadata are specified, like payment or
advertising metadata.
To ensure compatibility with as many applications and existing metadata collections as possible,
the attributes of the core and optional specifications of the P2P-Next Rich Metadata specification
are mapped to three state-of-the-art metadata standards: TV-Anytime, MPEG-7, and URIPlay.
Additionally, the Channel Metadata extensions provide a solution to describe the programming
guide of a TV channel such as BBC 1.
The two-step metadata creation process is illustrated in Figure 18.
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Figure 18: A two-step P2P-Next metadata creation (Courtesy: P2P-Next project)
The P2P-Next Metadata Specification also include a ‘Signpost Specification’ called Kendra, which
provides a concept for content providers to ingest their content into the Next-Share system
supporting various metadata schemes The Signpost implementation enables the translation of the
metadata of content providers to a scheme compatible to the P2P-Next Rich Metadata specification
and thus provides a convenient way for content providers to ingest all their content in a Next-Share
compatible way.
Another part of the P2P-Next Metadata Specification represents the Content Collections
Specification which describes how the content can be announced to interested parties utilizing socalled ‘Atom feeds’. The specification describes the discovery feeds, which provide an overview of
the available live programmes and on-demand collections of a single content provider, and the
content feeds, which provide more details for specific content collections.
Table 6: P2P-Next Core Attributes
A unique identification of the file.
The title of the file.
A description of the file's content.
The user that ingested the file into the P2P system.
The duration of the content in a suitable time unit, if the content has a timeline, or
none if the content has no timeline.
An indication of the chapters of the content, or none if the content has no chapters.
Creation Time
The time when the content was produced.
The language of the content.
The language of the subtitles of the content, or none if there are no subtitles.
The language of the captions of the content, or none if there are no captions.
Age Appropriateness
The rating in respect of the age appropriateness of the file.
The AV attributes of the file, like the file-format, the bit-rate or the frame-rate of
the content, etc.
The original producer of the content.
The genre of the content, e.g., a documentary.
Describes the series and the episode of the content, if applicable.
European Content
Describes if the content has been produced in Europe.
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Table 7: P2P-Next Optional Attributes
Business Model
Describes the business model applied for consuming the content.
Live Content
Describes if the content is distributed as live transmission.
Target Group
Provides information about the target group. Such information include the age,
gender, country, etc.
Allow Advertising
Specifies if advertising may be provided together with the content.
Circular Content
Describes if the users are allowed to redistribute the commercial content.
Ad Type
Describes the type of advertisement.
Streaming Type
Describes how the advertisement provided, i.e., in- or out-stream.
Ad Format
Describes how the advertisement is integrated into the content, e.g., as
Content Format
Describes the content format of the advertisement, including its resolution,
Payment Identifier
A second identifier of the content, as a payment system should not be aware of
the content for privacy reasons.
The price of the content.
The currency for the price.
Payment Recipient
The recipient of the payment, if the content is not offered for free.
Accept Donations
Describes if voluntary donations for the consumption of the content are
Advanced Information A link to a website with further information on the payment system.
Layer Information
Information about the layers of a scalable bit stream.
SPS Information
Information about the Sequence Parameter Sets (SPS) of the bit stream.
PPS Information
Information about the Picture Parameter Sets (PPS) of the bit stream.
In the table above, optional attributes for three categories are provided. The attributes provided
for advertising are used to describe properties of the commercial content and how they can be
displayed together with the actual content. The payment attributes provide the information
needed for acquiring a specific content. The attributes provided for scalability are only required for
scalable bitstreams and provide the scalable header information to the packetizers and depacketizers of the P2P system.
These optional attributes provide an initial metadata support for the P2P-Next business models, but
each of the categories might be enhanced or additional categories might still be added in the
course of the project. Please note that also additional metadata that are not described in this
specification might very well be used within the P2P-Next system.
P2P-related Digital Rights Management Systems
Digital Rights Management (DRM) is a system for protecting the copyright of data by enabling secure
distribution, access or usage to authorized users. There are two methods of preventing consumers
using content illegally: a) hardware-based and b) software-based methods. These methods are not
specific to P2P but generally apply to any media distribution across Internet. Software-based
solutions are more flexible than hardware ones, and involve encrypting or marking the content with
a digital watermark. Once the content is encrypted, a license is required allowing (or not) the user
to use the media. The license consists of a key to unlock the content and a set of media usage
rights (e.g. play only, play and record, single play, play for 30 days, etc.).
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Legal and Regulatory Matters pertaining to P2P16
This section addresses some specific P2P-related legal issues that may be relevant for Internet
delivery of TV and radio. For a long while, P2P has been synonymous with illegal file sharing
activity akin to those of Napster and Kazaa. The music industry has been taking legal action against
file-sharers and against companies that have made P2P file-sharing possible, but has largely failed
to stop the massive scale of copyright infringement that happens over P2P networks.
Out Law
News,, research published in July 2009, illegal file-sharing activity amongst 14
to 18 year olds has gone down from 42% to 26% over the past two years. The research demonstrated
that the music industry could best battle piracy by creating attractive legal routes to the
acquisition of music, whether this is an unlimited streaming service such as Spotify or a service
such as Virgin’s which aims to offer unlimited MP3 downloads as well as unlimited audio streams.
Young people find services such as YouTube much more convenient for checking out new music
than file sharing.
The former European Commissioner for the Information Society, Vivian Reding, launched a Digital
Europe Strategy in 2009, in which she called on the content industries of Europe to create services
which compete with piracy. She declared that ‘...Internet piracy is a vote of no-confidence in
existing business models and legal solutions – it should be a wake-up call for policy makers’.
16.1 Distinction between Scheduled versus On Demand content
It has been shown in this document that audiovisual (AV) services delivered over P2P networks can
carry a variety of different types of service, including live streaming, progressive download, ondemand streaming, on-demand download, catch-up and podcasting services. The Audiovisual Media
Services Directive (AVMS Directive), formerly called the ‘Television Without Frontiers’ Directive, is
based on the assumption that a clear distinction can be made between non-linear services - Video
on Demand (VoD) and linear services (scheduled programmes).
The question is whether, and more importantly, how, the AVMS Directive applies to these AV
services. This question is important because the rules applied for linear services are somewhat
tougher that those applied for non-linear services.
Under the definitions in the AVMS Directive it is clear that catch-up and podcasting services come,
in principle, under the rules for non-linear services. However, it should also be noted that the
definitions in the AVMS apply for the purposes of this Directive only.
It is important to realize that, despite the distinction, both linear and non-linear services are
covered by the new AVMS Directive, which is already recognition of their convergence. The
Directive maintains the principle of technological neutrality, so that the rules applicable to linear
services apply in a horizontal manner, independently of the technical modes of signal delivery
(over-the-air, by satellite, cable, broadband, microwave, telephone line, format, resolution,
screen-size, protocol, etc.). Transmissions via the Internet or mobile phones which are not
triggered by the consumer himself thereby remain a broadcasting act, whether the technology used
for the act is based on P2P delivery, via point-to-multipoint or otherwise. The new notion of linear
services has therefore safeguarded broadcasting from becoming a mere technology-dependent
activity and is therefore a crucial achievement also vis-à-vis the use of P2P technology by
This section was produced with the assistance of the EBU Legal Department
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16.2 European content
Article 3(i) of the AVMS Directive states that on-demand audiovisual services should promote
European works but does not impose any quotas. The quota provisions only apply for television
services or linear services but have been unchanged. Only certain categories of programmes, such
as feature films, television films and series, are subject to the quota system. The following are
excluded from the system: news, sports events, games, advertising, teletext services and
teleshopping. The promotion of European works should not apply to user-generated content.
However, Member States are free to adopt stricter or more detailed rules for media services
provided under their jurisdiction. They had until the end of 2009 to implement the provisions of the
AVMS Directive in their national law.
16.3 Advertising rules
In the AVMS Directive only quantitative rules based on insertion and hourly limits for advertising
exist, and they have been relaxed for television advertising. No quantitative rules exist for nonlinear services. For example, the quantitative limit on advertising spots, which is the most relevant
in practice, is 12 minutes per hour. Moreover, the 20-minute rule (which required that at least 20
minutes elapse between each successive advertising break within a programme) has been
abolished. In addition, the principle of separation of advertising and editorial content has been
maintained but has been reformulated in a way which opens up more possibilities for the use of
new advertising techniques.
Thus, Members States are free to adopt more liberalized rules for non-linear services, bearing in
mind that it is ultimately the user who decides. Too much advertising kills advertising.
However, all media audiovisual services (linear and non-linear) are subject to ‘qualitative’ rules (on
the protection of minors, on human dignity and on public health).
16.4 The (future?) role of ISPs
European countries seem to have different approaches towards Internet users who share illegal
content and exceed certain limits of file sharing. France, for example, seems in favour of the socalled graduated approach which allows, upon the decision of a special body, Internet service
operators to remove a customer’s Internet connection after repeated offences following on from a
warning. Sweden has not adopted this graduated approach, but allows content owners, as in other
countries, to sue infringers before the courts. It remains to be seen what the developments in other
Member States are. At the moment, there is no specific legislation on this issue envisaged at the EU
It must be recalled that the ‘graduated approach’ favoured by France is not officially linked with
the EU Enforcement Directive, but is an initiative on the basis of a Government-commissioned
report (the ‘Commission Olivennes’) for which most media stakeholders in France - as well as the
French association of ISPs - have provided their express support. On the other hand, consumers and recently the European Parliament in the current revision of the European telecom rules - have
opposed this approach, arguing that a costumer's Internet connection should not be cut off unless
there is a prior decision by the judiciary. Whether such a gentleman's agreement - and broad
support - could be obtained in other countries remains to be seen, given that, so far, the proposal
has not been openly embraced in Europe. Clearly, several categories of right-holders consider the
ISPs the best-placed to act against unlawful file-sharing (given that the ISPs profit from their
subscriptions). It could be argued that, although the graduated approach seems to include a
practical remedy to reduce, at least over time, the number of ‘innocent’ copyright infringers (those
uploading protected content without authorization but without knowledge that the act is unlawful),
it could well be that to achieve that effect a warning system as such would be sufficient. After all,
the main difficulties with the proposed final measure (the annulment of the ISP subscription) are
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1) its appropriateness, as such annulment would cut off complete access to a network which is used
for many other purposes too (and possibly by other persons within the same household),
2) the replacement of judicial relief by administrative proceedings (and therefore shifting litigation
costs to society as a whole), and
3) its presumably limited effectiveness with regard to professional infringers who would probably
find ways of continuing to keep their activities anonymous.
For example, the United Kingdom Government recently threatened the UK ISP and broadband
providers with a compulsory levy if they did not come forward voluntarily with a warning system.
This matter is likely to be debated again later, as it could be one of the major issues when the eCommerce Directive (which includes the most relevant liability provisions for ISPs) goes through its
revision process.
16.5 Global Internet Licence
The idea of a ‘global Internet licence’, as originally proposed some years ago by consumer
organizations and musicians' societies in France, during the debate on the revision of new French
copyright law, has not yet achieved support from other stakeholders in the copyright community.
This is not surprising because it is thought that such ‘culture flat rate’ should then apply to all
works and protected matter on the Internet, without bearing in mind that music is used and
consumed differently (in particular, repetitively over a long period of time) from, for example,
films and television series. Given the peculiarities of music usage, such a flat fee concept would
thus not be appropriate for all types of works. Moreover, the conditions of such permitted use do
not need to be the same for all works, as it could be liable to undermine legal (and paid-for) offers
via the Internet.
For example, at first sight the nature and modes of exploitation of audiovisual works (such as
feature films) would be unlikely to fit easily into a collective fee scheme. However, the underlying
concept of a collective ‘flat fee’ payment has certain similarities with existing (collective) licensing
practices as regards massive use of music (e.g. by broadcasters) and is therefore certainly worth
analysing and exploring in more detail. This is particularly the case since any other legal remedies
to Internet piracy of music have so far proven ineffective or inadequate. Such a concept, if
thoroughly developed, could also be more favourable to the less well-known musicians and would
then be a far better approach than, for example, the idea of extending the term of protection for
performers and record producers.
16.6 Must carry
Must-carry rules seek to ensure that consumers have access to a wide, varied range of radio and
television channels and services. The rules are thus an important instrument whereby Member
States can guarantee media pluralism, cultural diversity and consumer protection. They remain
essential in the digital environment.
In the context of the review of the Telecom Package, the European Parliament followed, in its
second reading (6 May 2009), the Council position not to extend the potential scope of must-carry
rules to non-linear audiovisual media services. Nevertheless, the text now at least ensures that all
complementary services, and not just accessibility services (as in the Commission proposal), can be
covered by must-carry rules, and that there is no mandatory review every three years.
Must-carry rules are of potential benefit with regard to not only traditional cable television
networks but also other ‘closed’ networks, where all media services are provided/controlled by the
service/network operator (such as IPTV services offered by broadband access providers). On the
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other hand, must-carry rules are not an appropriate instrument with respect to ‘open’ networks,
where there is open access and where media services are provided/controlled by the media service
providers themselves (e.g. on the open Internet). For the latter, the principle of net neutrality is
more relevant.
16.7 Net neutrality
Must-carry rules are not an appropriate instrument with respect to ‘open’ networks. As the Internet
is an essential platform for broadcasters and other audiovisual media service providers for the
distribution of non-linear audiovisual media services to the general public, the open architecture of
the Internet, underpinned by new legal concepts of ‘net neutrality’ or ‘openness of the Internet’, is
of crucial interest. Must-carry rules and net neutrality principles can thus be seen as
complementary instruments.
Broadcasters are expected to use all available platforms including terrestrial, satellite, cable,
broadband and the Internet for the distribution of their non-linear audiovisual media services. The
Internet is an indispensable platform. One problem that has already emerged in several European
countries relates to the recurring demands by network operators that broadcasters (and other
audiovisual content providers) should pay if they do not want their content to be slowed down on
the Internet. This could lead to a dramatic increase in distribution costs for broadcasters and other
content providers.
The concept of net neutrality is based on principles such as transparency of network management,
minimum requirements as regards ‘quality of service’, and non-discrimination with respect to
content, applications, services, providers and users. Net neutrality is thus likely to play an
important role in facilitating the distribution of (linear and non-linear) audiovisual media services
to the general public, irrespective of whether these are provided by public service media, by
commercial media or by individual users'.
The discussion on net neutrality has developed in Europe only recently, in contrast to the United
States. This may be explained by the different business models used by Internet access providers in
the US and in Europe (with the effect that problems with net neutrality first arose in the United
States), and by the different regulatory environment for the telecom sector in Europe (which has
been harmonized, as far as EU and EEA Member States are concerned, by a bundle of EU Directives
which are generally referred to as the ‘Telecom Package’).
Under the current EU Regulatory Framework for electronic communications services and networks,
it is possible or even mandatory for national regulatory authorities to impose, on operators
designated as having significant market power, certain obligations regarding access or
interconnection (see Articles 8-13 of the Access Directive). However, such measures primarily serve
to ensure effective competition among telecom operators, and do not directly protect end-users.
The new telecoms regulatory framework adopted in 2009 ensures that European consumers have an
ever greater choice of competing broadband service providers available to them. Internet service
providers have powerful tools at their disposal that allow them to differentiate between the various
data transmissions on the Internet, such as voice or 'peer-to peer' communication. Even though
traffic management can allow premium high quality services (such as IPTV) to develop and can help
ensure secure communications, the same techniques may also be used to degrade the quality of
other services to unacceptably low levels. This is why, under the new EU regulatory framework,
National Regulatory Authorities are required to promote ‘the ability of end-users to access and
distribute information or run applications and services of their choice.’ This sets a very important
principle for net neutrality, as it recognises and safeguards the basic freedoms of Internet users
The new framework explicitly foresees the possibility for National Regulatory Authorities, after
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consulting the Commission, to set minimum quality levels for network transmission services so as to
promote ‘net neutrality’ and ‘net freedoms’ for European citizens. This should ensure that traffic
management and possible prioritisation does not lead to degradation of content and services
provided by non-commercial actors or by new entrants.
In addition, thanks to the new transparency requirements, consumers will be informed – even
before signing a contract – about the nature of the service to which they are subscribing, including
traffic management techniques and their impact on service quality, as well as any other limitations
(such as bandwidth caps or available connection speed).
16.8 Country-of-origin-of-initial-transmission
Another legal issue that would need to be considered in the context of Internet TV services is the
question which law should apply to those services, given that, if the public part of the Internet is
involved, the initial transmission of the content may cross national borders. For media law
purposes, the AVMS Directive upheld the rule under the former Directive that the pertaining law is
that in the country in which the originator of the broadcast resides (with certain exceptions for
services specifically targeting foreign countries). A similar rule exists under the 1993 Satellite and
Cable Directive for satellite services (the act of communication is determined by the law of the
country of the satellite uplink). Much can thus be said for applying the same principle to Internet
Discussion on xDSL Network Asymmetricity
The vast majority of Internet use today is for high speed download from a service provider to the
consumer. Where business users required a symmetrical service, the initial solution was the
Integrated Digital Services Network (ISDN). ISDN offered guaranteed quality of service (QoS) and an
equal data rate in both down (from server to user) and up (from user towards server) directions. As
user content has increased in both directions, ISDN was no longer sufficient.
To this end, DSL (Digital Subscriber Line) broadband connections came into operation. However,
DSL local loops are generally highly asymmetric and may provide a limited upstream data rate;
therefore they are less suitable to support video-conferencing and P2P traffic17. To provide a higher
upstream data rate, the DSL infrastructure would require a significant re-design and reengineering. As this is unlikely to generate new revenues and provide a viable business case,
telecom companies seem not interested in making their networks more symmetric.
In February 2008 the EBU Technical Committee posed the following question:
‘What are the limitations of P2P networks for video streaming if users utilize asymmetric lines
with limited upstream capacity?’
A collective response from Project Group D/P2P is given below.
17.1 Members experiences
Several EBU members have evaluated the live TV distribution over P2P networks with a high degree
of asymmetry.
The VRT carried out a test with the Octoshape P2P system for the Tour De France in 2007, where
they streamed at 1.5 Mbit/s. ADSL lines in Belgium are mostly highly asymmetric, using upstream
Services such as Slingbox could also be enabled by making DSL more symmetric. Slingbox relays a home television
receiver viewing via the Internet to any other location.
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capacity of 256 or 512 kbit/s. Some larger network providers have symmetric lines but some of
them block P2P traffic.
The VRT's experience is that, because of the limited upstream capacity, the P2P grid did not
contribute much to the overall bitrate. Most capacity needed therefore came from the central
servers. These servers can be spread over the different ISPs (as in a simple CDN).
The WDR’s experience from the Rock-am-Ring festival is that the P2P/Unicast ratio of live
streaming using Octoshape’s P2P system was 40% - 60% at a bitrate of 700 kbit/s.
Hence the VRT believe that P2P is today most useful for radio/audio streaming and low quality
For high quality video the gain for the broadcaster compared to Unicast is very limited.
17.2 Technical discussion on Asymmetry
The Network Asymmetry (NA) is the ratio of upstream capacity (UC) to downstream capacity (DC).
NA = UC / DC
The following is a real-life example with nominal numbers:
‘Swisscom’: NA = 0.6 Mbit/s / 5 Mbit/s = 0.12
‘ADSL 16’: NA = 1 Mbit/s / 16 Mbit/s = 0.065
NA tends to increase with more complex technologies such as ADSL 2 and ADSL 2+ in some markets.
Quite in contrast the VDSL-Flatrate offerings of Deutsche Telekom comprise
‘VDSL 25’: NA = UC/DC = 3 Mbit/s / 25 Mbit/s = 0.12
‘VDSL 50’: NA = UC/DC = 5 Mbit/s / 50 Mbit/s = 0.10
Generally, the bigger the ratio of the access, the better it can be used by P2P-applications. In the
examples above some networks which provide potentially a better P2P performance (due to the
higher upload-capacity) have a lower ratio.
Using nominal numbers of the connection capacity makes it difficult to prove the individual P2P
usability by this ratio. More significant information can be achieved by using values of the
bandwidth used by the received material (SB) and the upstream capacity (UC) (nominal or better
which is available for the applications upstream).
The efficiency of the P2P grid depends on the ratio (R) between the (available) upstream capacity
(UC) and the media stream bandwidth (SB).
R = UC / SB
This results, for the examples mentioned above, (3.5 Mbit/s streaming material and about 80% of
available upstream bandwidth):
‘VDSL 50’: R = UC/SB = 4 Mbit/s / 3.5 Mbit/s = 1.14 (in contrast to the NA = 0.10)
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‘ADSL 16’: R = NA = 0.8 Mbit/s / 3.5 Mbit/s = 0.23 (in contrast to the NA = 0.065)
Three use cases apply:
R >= 1
In this case the media streams are of lower bitrate than the usable upload bandwidth, typically
audio only or low-definition video. The efficiency of P2P grid is high and no additional caching or
CDN is required.
Typical cases: Assuming UC = 600 kbit/s
SB = 100 kbit/s audio stream (e.g. AAC stereo) (-> R = 6)
SB = 200 kbit/s video stream (e.g. for QVGA screens - mobile phones) (-> R = 3)
SB = 450 kbit/s video stream (e.g. for VGA screens - portable devices) (-> R = 1.33)
1 > R >= 0.75
In this case, the media streams are larger than the upstream capacity of the network, albeit of the
same order of magnitude. The P2P network is no longer able to perform all the distribution only by
itself - additional help from the server-based technologies is required (either in the form of ‘superpeers’, caching servers or small-scale CDNs)18.
Typical case: Assuming UC = 600 kbit/s
SB = 700 kbit/s video stream (-> R = 0.86)
R < 0.75
In this case, a standalone (pure) P2P grid is no longer able to perform the distribution of the media
streams. The distribution predominantly relies on a server-based distribution such as CDN. A P2P
grid, superimposed to CDN, can complement CDN to improve its scalability (but cannot replace it).
Typical cases: Assuming UC = 600 kbit/s
SB = > 1 Mbit/s video stream (‘standard Internet TV’) (-> R = 0.6)
SB = > 2 Mbit/s video stream (sometimes called ‘HDTV Internet TV’) (-> R = 0.3)
In addition it should be mentioned that available upstream capacity can be partially reduced by
firewalls, parallel usage and data volume-based pricing of ISP.
Media Quality is steadily being improved. There are three reasons for that:
Networks: upstream capacity of DSL lines is improving, as DSL line capacities are generally
going up (both in terms of downstream and upstream, although in different proportions). In
addition, links become more and more symmetric (consumer SDSL, HDSL, VDSL2+) in some
It should be pointed out that there are only a very limited number of P2P solutions that are technically capable of using
upload capacity in CASE 2.
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Audio and video compression technologies: have recently made significant improvements
and are more and more efficient, both in encoding and decoding. For example, the state-ofthe-art Advanced Audio Coding (AAC) is about 3 times more efficient than MPEG-2 Layer 2
coding developed about 10 years ago (AAC requires 3 times less bit rate to achieve the same
The third reason is the progress in P2P technologies (such as Octoshape) which are able to
benefit from many new approaches (for example, exploit even small upload contributions
from ‘stand-by’ users).
The above technology advances may allow the standalone P2P networks in the next five to ten
years to become a viable distribution mechanism even for ‘standard TV quality’.
Service continuity: As the number of peers in the network varies over the time (and may
eventually increase to several tens of thousands), it is important to keep the service running
continuously. P2P has a unique capability (compared to CDNs) of avoiding a ‘single point of failure’
(which may occur in case peers come and go). Also, P2P is capable of scaling down quality
(lowering media stream bitrate) smoothly, if the number of peers suddenly increases (thus
increasing the need for aggregate upload capacity).
Scalability: The P2P systems are highly scalable both in terms of media quality and numbers of
simultaneous users. This is particularly important for covering live events with unpredictable size of
Cost aspects: For CASE 1 systems, commercial P2P systems are currently significantly cheaper than
CDNs (approximately by an order of magnitude), measured as cost per gigabyte, although this cost
gap is getting less.
Progress in P2P systems: use of standby users: Octoshape is able to benefit from using upstream
capacity contributions from standby (idle) peers who are not using the upload capacity by
themselves. Such contributions are generally very small, however since the number of such peers
may be large, such contribution may become significant to help with the upload deficit to the
peering users.
17.3 Some conclusions on asymmetry
The upstream capacity limitations of today's access networks (including DSL, HSPA, WiMAX, etv)
severely affect the functioning of P2P systems. Nevertheless, it is really the ratio between the
upstream network capacity and the media stream bitrate that matters, as identified in the three
use-cases above. In CASE 1, where media streams are of lower bandwidth, P2P generally should
work fine as a standalone system, and should be scalable and cheap. In CASE 2, P2P requires a
limited support from the server-based technologies. CASE 3 requires a significant contribution from
the server-based technologies.
In other words, currently no true HDTV quality is possible with the pure (no caching) P2P
distribution systems in regions with highly asymmetric networks (such as existing ADSL networks in
Europe). However, due to advances of the DSL networks, audio and video compression technologies
as well as P2P system, P2P is gradually expanding into a better quality media delivery zone.
For the future it is likely that a combination of CDN and P2P will prevail, whereby the share of
CDNs will gradually diminish, as the media technologies and networks advance.
Some benefits of SVC and MDC redundant coding methods are being considered to gain maximal
value from the use of asymmetric connections.
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Trends in P2P Research and Development
18.1 P2P-Next
The Next Generation Peer-to-Peer Content Delivery Platform (P2P-Next for short) is an EU FP7 Collaborative Research (Large Scale Integrated Project)
which started in January 2008 and is due to end in 2011. The objective of P2P-Next is to build an
open peer-to-peer-based content delivery platform, supporting broadband video portals and
delivering content via P2P to TV screens via STBs, and PCs. The P2P-Next system is designed to
include payment and DRM functions, as well as functions to help content producers turn linear
video content into interactive content. The goals are also to define use cases and sustainable
business models for the P2P-Next system and the various actors and users.
At the time of writing, the P2P-Next project team had reported a number of technical
achievements for the first 24 months. Among those, the highlights are the streaming video-to-STB
solution (exhibited at IBC 2008), the Internet-HD quality end-to-end streaming distribution of
professional content to low-cost STB hardware (exhibited at IBC 2009). A number of trials have
been conducted in the Living Lab and a large number of users (unique IP addresses) have
successfully installed and executed the software.
The main strength of the project is in the large scale of integration it pursues. In addition to the
P2P core functionality the project promotes a practical approach to content nonlinearity and
interactivity (the LIMO concept), as well as several other fundamental elements of the media
delivery and consumption chain.
Following the audit in March 2010, the Commission stated that most of deliverables have been
delivered in time, except for the mass production of the NextShareTV CE device. This milestone has
been delayed because of technical problems which are beyond the control of the P2P-Next team.
The P2P-Next platform approach allows modular development and modular applications, enables
knowledge sharing and facilitates technology integration, code- and skill re-use. This translates to
fast development of new content delivery applications that build value for service and content
P2P-Next will advance the state-of-the-art in important areas, including evolutionary content
distribution, easy access to vast amount of content with metadata federation, social networking,
and innovative business models for advertising. The sum of these advances is a large step towards
moving the information access from the hands of a producer to the hands of the consumer, and
allowing consumers to enjoy and utilize content resources in a mobile and pervasive manner, across
the great online space.
Distribution of radio and television programmes, movies, music, ring tones, games, and various data
applications to the general public is today possible via a variety of dedicated networks and special
end user terminals. As broadband Internet becomes ubiquitous, all content distribution services will
be combined (bundled) and conveyed to the general public via a common pipeline – the Internet.
Today several technologies are used for the media distribution across the Internet: Unicast, IP
Multicast, content distribution networks and most recently – Peer-to-Peer (P2P).
P2P-Next will be developed through collaboration with European and national initiatives, as well as
some of the largest and most important actors in the media and telecommunications sector,
ensuring industrial relevance and worldwide application reach. P2P-Next involves 21 partners in 12
different countries, including large European players to ensure the future project's sustainability,
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SMEs, universities and R&D institutes to manage highly-focused technology components19.
Broadcasters and content providers consider P2P-Next as a promising approach towards a futureproof, universal, and ubiquitous two-way (interactive) distribution mechanism. P2P-Next seems to
be well positioned to complement the existing distribution mechanisms such as satellite, cable and
terrestrial networks.
The P2P-Next Project extends the notion of a conventional media distribution network. It
introduces a concept of on-demand, personalised and social network.
In the following some details of P2P-Next are given.
P2P-Next is an overlay to the existing infrastructure
The P2P-Next system is an application-layer media delivery system, which can in principle be
overlaid to any two-way communication system. Media delivery does not require a dedicated
network such as the DVB-H or 3G networks. Therefore,
P2P-Next requires much lower infrastructure investments (no ‘streaming farms’ are required),
management costs and maintenance costs compared to dedicated distribution networks.
P2P-Next may dramatically improve the network economics
P2P-Next changes the conventional business model for media distribution over the Internet. Using
conventional technologies (e.g. Unicast, IP Multicasting, content distribution networks),
distribution costs are proportional to the number of users, the bandwidth required and service
quality required (SLA).
P2P-Next cost is not directly proportional to the number of users; in fact, the cost per user
diminishes with the number of users. Therefore, P2P-Next significantly reduces distribution costs.
The number of services that can be accommodated is practically limitless. Note that conventional
systems do require frequency spectrum, which is a scarce resource and has a limited capacity of
To this end, P2P-Next may considerably ease regulatory and frequency management problems.
P2P-Next approach is NOT limited to computers
The concept of P2P distribution can be ported to virtually any consumer-electronics terminal
devices such as DVB set-top boxes and home gateways. For reasons of interoperability, such P2P
solutions need to be standardised and validated. Embedded P2P-Next devices could be used for
open Internet access as well as closely controlled and managed IPTV systems.
Extension of P2P to connected non-PC devices can dramatically change the business model of media
distribution. In this manner, P2P-Next could become platform- and device agnostic.
The P2P-Next Project plans to contribute to worldwide standardisation of an open-source,
scalable, and modular P2P plug-in, which can potentially be embedded in any CE media device.
P2P-Next is a win-win technology as it helps all actors in the value chain
By rolling out P2P-Next services, all actors of the media distribution value chain could benefit
P2P-Next includes several public broadcasting organisations including, RTVSLO, BBC and EBU
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Content owners and providers can enlarge their markets and can make more profits.
For broadcasters, P2P-Next can represent yet another outlet for distributing their
programmes and contents.
Consumer manufacturers and IT manufacturers could sell more hybrid20 STBs and other
devices. As the market grows, prices go down.
Network providers will benefit as the overall network load will be reduced – P2P packet
paths are much shorter than conventional in traditional server-client networks.
P2P-Next aims to support all actors in the media distribution value chain.
P2P-Next provides live steaming, downloading, and progressive downloading
It has been often stated that the audio-visual media are moving away from linear channels and are
becoming more and more on-demand, thus available to the end user when they want them, where
they want them, and on any terminal.
The P2P-Next system will help end users to live-stream a TV channel, download a song or video
clip, or progressively download a file (and watch it while it is being downloaded).
P2P-Next enables horizontal market solutions
As P2P-Next is a non-proprietary, open source, open standard solution and will be put forward for
international standardisation. It will enable the deployment of a horizontal market. A not-for-profit
foundation will be established to roll out P2P-Next technology and perform the required product
compliance and interoperability tests.
P2P-Next will facilitate the opening of horizontal markets for any kind of business.
P2P-Next facilitates social networking
One of the underlying principles of any P2P system is the participation of several peers in a
common activity (for example, sharing a video clip). P2P-Next will facilitate the introduction of
several social features in content distribution: communication primitives, strong peer
authentication, strong content integrity checks, permanent storage of context, semantic clustering,
recommendations, reputations, micropayments, etc.
P2P-Next will enhance P2P distribution with social networking features to support user and
business communities.
P2P-Next development is driven by actual users
There are many examples of promising technical solutions that dramatically failed, because users’
perception did not match with marketers’ vision. Much of the 2001 Internet bubble collapse was
caused by this phenomenon.
In P2P-Next an incremental approach will be followed by early and short-cyclic releases involving
actual user communities (living lab approach).
‘Hybrid’ implies both broadcast and broadband front ends.
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P2P-Next Content generation and distribution
The P2P-Next project designs the mechanisms for professional content distribution, which is
particularly interesting for public broadcasters. The project has adopted metadata standards based
on MPEG-21, MPEG-7 and TV Anytime, designed a lightweight interactivity mechanism (LIMO) based
on the emerging HTML 5 standard, and defined how content will be packaged and delivered within
P2P-Next. The adoption of the Kendra Signposts service for the metadata transformation has the
potential to attract a larger base of professional content providers. Temporal addressing of content
segments and its recommendation to friends is highly valued by the users and hence should be
provided on the STB.
A basic toolbox was developed that covers the control, management and ingestion of VoD content.
The P2P-Next Rich Metadata specification has been extended with the specification of optional
metadata, i.e., advertisement, payment and scalability metadata. ATOM Feed based content
discovery has been implemented on the STB and was demonstrated at IBC and NEM Summit in 2009.
P2P-Next PC and CE device platform
The PC platform is designed and prototyped and is addressing several advanced features such as
SVC and MDC coding, zoomable UI, adaptive media playout and forward error correction
techniques, etc. The current SVC decoder implementation is not real-time, which might turn out as
a risk to the end-to-end demonstration of the benefits of content scalability.
Developments of the low-cost CE platform, supporting the NextShare applications, have been
pursued. An EPG and an ATOM-based Feed Navigator, allowing content discovery by end-users have
already been implemented. Initially, the P2P network stack was based on Python but exhibited
performance limitations (in terms of computational complexity and resource requirements) when
running on the P2PNextshare CE hardware platform. Effort has then been dedicated to the
development of an optimized version of the NextShare content transport to allow for higher bit
rates and lower memory resource utilization.
The mass production of the units to be used in the Living lab trials has been slightly delayed due to
technical problems in the manufacturing of the SoC (system on a chip), which are beyond the
control of the P2PNext consortium. The support for SATA storage has been lost and the consortium
is compensating for it by relying on USB flash media. It has been agreed that 300 units will be
manufactured, instead of the original 500 budgeted for in the Living lab trials.
SWIFT protocol
One of the focus points of the P2P-Next project21 is to develop a generic content-centric multiparty
transport Internet protocol called SWIFT. This protocol is designed to distribute content very
efficiently among a swarm of peers using UDP with LEDBAT (Low Extra Delay Background Transport)
congestion control. Once developed and tested, SWIFT will be capable of integrating smoothly into
current and future browsers and operating systems accommodated in practically all consumerelectronic devices including set-top boxes, televisions, mobile and portable devices, so that it will
be able to serve most of the Internet traffic.
As of March 2010
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18.2 SmoothIT
The project has the following major objectives to be pursued in support of the overall aim of
radically advancing technology:
SmoothIT will structure overlays in a way that is efficient or optimal, both for user
communities and for ISPs. This is to be attained by means of economic and incentive
SmoothIT will study and define key requirements for a commercial application of economic
traffic management schemes for ISPs and Telcos.
In order to advance traffic management beyond traditional limits, specialized economic
theory will be applied for building, in a fully decentralized way, network efficient Internetbased overlay services in multi-domain scenarios, solving the information asymmetry
SmoothIT will design, prototype, and validate the necessary networking infrastructure and
their components for an efficient implementation of such economic traffic management
mechanisms in an IP test-bed and trial network.
SmoothIT will develop an optimized incentive-driven signalling approach for defining
(theory) and delivering (technology) economic signals across domain boundaries in support
of co-operating and competing providers in an interconnected heterogeneous network
SmoothIT will integrate concepts from previous work, such as M3I and MMAPPS, leveraging
existing knowledge and applying it to future overlay services.
SmoothIT will stress operator-orientation by verifying key results of the work through ISP
and Telco requirements as well as its supporting technology.
TV services over the Internet can be provided either by exploiting IP Multicast functionalities or
relying on a pure end-to-end (P2P) approach. The first technique unfortunately will only work on a
network infrastructure controlled by a single broadband operator due to limitations of IP Multicast
facilities. The P2P approach, on the other hand, has been successfully exploited to overcome these
limits and can potentially offer a scalable infrastructure. Recently, several P2P-TV systems started
up, with the last generation offering High Quality TV (P2P-HQTV) systems, providing a ubiquitous
access to the service. These same potentialities of P2P-TV systems constitute a worry for network
carriers since the traffic they generate may potentially grow without control, causing a degradation
of quality of service perceived by Internet users or even the network collapse (and the consequent
failure of the P2P-HQTV service itself!).
Starting from these considerations the NAPA-WINE project, funded by the European Commission
within the seventh framework programme, aims at:
providing a careful analysis of the impact that a large deployment of both general P2P-TV
and P2P-HQTV services may have on the Internet, through an in detailed characterization of
the traffic they generate;
providing guidelines for P2P-TV developers regarding the design of systems that minimize
the impact on the underlying transport network while optimizing the user perceived quality;
providing a road map for Internet Service Providers to better exploit the network
bandwidth by showing simple and minimum cost actions that can be taken in presence of
P2P-TV traffic.
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18.4 NaDa
NaDa (Nanodatacentres),, is an EC funded project which
investigates into the next step in data hosting and in the content distribution paradigm. By enabling
a distributed hosting edge infrastructure, NaDa can enable the next generation of interactive
services and applications to flourish, complementing existing data centres and reaching a massive
number of users in a much more efficient manner.
Increased computational power, combined with advances in data storage and global networking,
has made Internet services a critical resource in our everyday life. Data centres (buildings that host
large numbers of networked computer servers and power supplies) are often critical enablers of
such services. Data centres are known to be a major source of cost and complexity for operators,
while they are inherently not scalable due to their centralised nature. As a result, router
companies, server manufacturers, and hosting facilities hasten to produce more efficient hardware
and software for data centres. They also try to improve the efficiency of operation of such
components. For instance, operators may dynamically shut down some processes in machines or
even entire machines, depending upon the current load. They may also redirect surplus load to
other idle machines in the same data centre. While this effort improves efficiency, it is bound to
produce rather short-term remedies. Indeed, the entire paradigm of monolithic data centres
seems to be challenged, not the specifics of their numerous possible realizations.
The changes in costs, combined with the observed changes in highly interactive demand profiles,
illustrate the need for a paradigmatic shift towards highly distributed data centres. NaDa is tailored
towards servicing interactive applications to a massive number of clients. This solution requires a
large number of geographically dispersed nano data centres (instead of a few large data centres).
In addition, it will materialise from the composition of pre-existing, but underutilised resources,
and thus does not require heavy capital expenditures. Indeed, there are large amounts of untapped
resources at the edges of the network today that, if integrated intelligently, could provide a
substantial complement to existing data centres, if not a complete substitute. Such resources
include: next generation home gateways, set-top boxes, wireless access points, etc. Most of these
devices are nearly as powerful as standard PCs, with a great deal of processing power and
reasonable storage, but unlike PCs, they are often idle and moreover controlled by a single service
provider. This idleness is largely due to ‘always-on’ user habits, which result in systems that are
being powered most of the time, despite most of their computing and storage resources remaining
inactive. Similarly, the (broadband) link that connects such boxes to the Internet stays idle for long
periods of time. The NaDa objective is to tap into these underutilised resources at the Internet
edge and use them as a substitute/aid to expensive monolithic data centres.
The NaDa approach is classic in one respect, and revolutionary in others. It moves content and
complexity to the edge, which is perfectly in line with the Internet’s original philosophy and offers
the maximum guarantee of network performance and availability (no additional complexity in the
network). However, it is a revolutionary approach in next generation Internet research, especially
when compared to the approach currently taken in the US which is to re-design the architecture of
the network core in order to better handle content instead of using existing resources at the edge.
Still, NaDa does not ignore the current CDN or cache-based content delivery architecture. In fact,
NaDa will use existing caches or CDNs to improve the quality of service experienced by users.
In order to combine all unused edge resources, NaDa will use a new, managed peer-to-peer (P2P)
communication architecture. The P2P paradigm allows the deployment of new services such as file
sharing or telephony quite easily without having to scale servers for peak capacity. However, most
of the currently deployed P2P systems have focused on simple file sharing or streaming applications
(and often for illegal content). Thus, several fundamental issues must be addressed in order to
invent a new P2P paradigm for the NaDa system.
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The IST VICTORY project (Audio-VIsual ConTent search retrieval in a distributed p2p repositORY),, which started in January 2007, aims to build a distributed repository of
heterogeneous visual objects, accompanied with related textual documents, videos and images
(MultiPedia objects). In light of three dimensional (3D) object retrieval evolving from text
annotation to content- and context-based and from standalone applications to web-based search
engines, VICTORY aims at the creation of a search engine for 3D and associated multimedia
distributed content into Peer-to-Peer (Ρ2Ρ) and mobile Ρ2Ρ (m-Ρ2Ρ) networks.
Driven by the very successful concept of Wikipedia (, the main goal of the
project VICTORY is to create the first distributed MultiPedia Object Repository. A Multipedia
Object is a 3D object along with its accompanied information i.e. 2D views, text, audio, video to
which any peer can contribute.
The main objective of VICTORY is the development of novel search and retrieval framework that
allows easy integration of different search methodologies. This will result in an integrated platform
which will allow processing and accessing data and knowledge by using ontology-based management
and semantic-based retrieval mechanisms.
The challenge within VICTORY is to bridge the gap between content-based and knowledge-based
search and to apply this really innovative technology to MultiPedia content, especially to 3D
Content-based search will be based on a) content, which will be extracted taking into account lowlevel geometric characteristics and b) context, which will be high-level features (semantic
concepts) mapped to low-level features. VICTORY aims at introducing a solution so as to bridge the
gap between low and high-level information through automated knowledge discovery and
extraction mechanisms. High level features will be a) appropriate annotation options provided by
the system or generated by the user dynamically (active learning) and b) relevance feedback where
the user will mark which retrieved objects he thinks are relevant to the query (user’s subjectivity).
These high level features are expected to improve significantly the retrieved results.
For supporting sophisticated 3D object search and retrieval, an ontological framework is needed
that will allow for combining text/metadata-based searching with 3D content searching. This
ontology will be used either as organizing principle to navigate through the 3D objects, or for
restricting/guiding the search through the objects’ classes. As a result, VICTORY will introduce
advanced search methodologies, in addition to the filename-based method prevalent in Ρ2Ρ
The search engine will feature novel multimodal personalized interfaces in order to take into
account the users’ interests and to offer capabilities of matching between 2D/3D objects (image to
3D), sketches and text (mixed-media queries). The search engine will be able to retrieve the
appropriate 3D object(s) along with its accompanied MultiPedia information.
VICTORY will also develop a P2P scheme so as to utilize not only the distributed data storage but
also the computational power of each peer for the pre-processing, interpreting, indexing,
searching, retrieving and representing of MultiPedia data. Through the VICTORY framework, users
will be able to handle, share and retrieve 3D and audio-visual data among peers around the world.
Moreover, every peer will be responsible for extracting and indexing the features of the shared 3D
data, thus the efficient manipulation of the 3D data will be accomplished.
The key driver for the design of the VICTORY P2P scheme is the enhanced Quality of Experience
(QoE) of the user. QoE can be realized as the combination of a multitude of Quality of Services
(ranging from bitrate, processing speed, and graphics quality, to power consumption). Existing P2Pbased standards and products are oriented towards content and services discovery while QoS (and
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QoE) issues for real-time demanding applications (such as 3D content manipulation and rendering)
have not been adequately addressed. The envisaged scheme will incorporate the protocols,
semantics, and intelligence allowing the negotiation of resources (computational, communications,
data storage, etc) sharing and the optimization of the P2P framework for enhancing the user
quality of experience. Moreover, the P2P collaborative framework will be capable of utilizing new
techniques to perform visualization and rendering of the retrieved 3D objects into low bandwidth
and processing power mobile devices. Finally, the search and retrieval efficiency of the system will
be improved by restricting the search procedures to the neighbouring peers. Copyright protection
and 3D objects’ ownership will be provided developing/deploying highly innovative 3D
watermarking algorithms and DRM.
Technical approach
The work in VICTORY is divided into four phases covering the following topics: Project management
and evaluation, research and development, prototyping and integration, and user testing and
validation. Research and development in VICTORY will mainly focus on the development of the
following components:
P2Pnetwork: involves research in P2P networking of standard PCs and mobile devices and
interoperability between standard and mobile P2P networks. The main objective of this
discipline is to develop a QoE (Quality of Experience)-aware P2P-based framework, which
will provide the advanced middleware infrastructure needed for the effective realization of
the VICTORY applications for 3D content searching and manipulation. This middleware
framework will allow standard and mobile peers to advertise, access, and negotiate the
sharing of available computational, communications, services, and content resources in a
user centric, flexible and secure manner.
3D Search engine: involves research into 3D content and context based search and retrieval
techniques, and their integration to a distributed P2P environment. The search engine will
consist of the following distinct parts :
3D low-level feature extraction algorithms
Annotation mechanisms
Relevance Feedback algorithms
Ontology Based Retrieval
2D/3D and sketch/3D matching algorithms
Multimodal personalized user interface: involves the creation of a user interface where the
user will be able to input information about himself, his interests and so on. Additionally,
the retrieved data will be visualized through the user interface where the user will be able
to interact with them (roto-translate the objects, change the rendering mode (wire frame,
solid, etc.), add/remove textures, add annotations, mark relevant results and so on). The
use of semantic concepts, interfacing with end-users’ interests, along with the different
modalities and the interactive capabilities are expected to provide great flexibility, high
efficiency of the retrieval process and ease of use.
Visualization on handheld devices: involves research so as to bridge the gap between high
quality 3D graphics and mobile devices. VICTORY will allow mobile users to search, retrieve
and finally display, on their own devices, extremely complexity scenes. The infrastructure
will be ‘flexible’ enough in order to support the widest spectrum of devices independently
of their hardware and operating system.
Security and Copyright protection mechanisms: involves research into security and
copyright protection techniques to guarantee secure delivery of 3D content across standard
and mobile P2P networks. This will be achieved firstly, using a DRM architecture that will
allow a super-distribution model of content distribution and secondly, protecting the
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MultiPedia content using a combined model consisting of two methods, 3D digital
watermarking and public-key encryption.
18.6 P4P
P4P [18] is a framework that can be used to enable Internet service providers (ISPs) and peer-topeer (P2P) software distributors to work jointly and cooperatively. P4P stands for ‘Proactive
network Provider Participation for P2P’. P4P is a set of business practices and integrated network
topology-awareness models designed to optimize ISP network resources and enable P2P based
content payload acceleration.
The P4P framework can be used to ascertain appropriate and voluntary best practices to accelerate
distribution of content and optimize utilization of ISP network resources in order to provide the
best possible performance to end-user customers.
P4P allows for more effective cooperative traffic control between applications and network
providers. The Yale University conducted extensive simulations and real-life experiments on the
Internet to demonstrate the feasibility and effectiveness of P4P. Their experiments demonstrated
that P4P either improves or maintains the same level of application performance of native P2P
applications, while, at the same time, it substantially reduces network provider cost compared
with either native or latency-based localized P2P applications.
18.7 Digital Video Broadcasting (DVB) Project
The Digital Video Broadcasting (DVB) Project is an industry-led consortium of around 300
broadcasters, manufacturers, network operators, software developers, regulatory bodies and others
in over 35 countries that are committed to designing open technical standards for the global
delivery of digital television and data services. To date, DVB has produced and published a number
of DVB IP television specifications, focused on ‘managed IPTV track’. During 2009, the DVB IPTV
group developed a document entitled ‘Commercial Requirements for Peer-to-Peer Internet-TV
Content Delivery’ which represented a first brick of the unmanaged ‘Internet-TV track’22.
18.7.1 DVB Commercial Requirements on P2P
The DVB Commercial Requirements on P2P document covers the deployment of DVB services over
unmanaged networks, such as the Internet, where at least one segment does not provide
guaranteed QoS and where advanced network features (e.g. Multicast) cannot be fully assured. This
means that no assumption can be made on availability or reservation of resources in the core and
access network. The system shall assume that only best effort data delivery can be used, i.e.
functionalities that the typical broadband Internet access provides today. Managed content delivery
networks are not considered here, although P2P could also be used in the managed, QoS-controlled
The DVB describes the complete set of commercial requirements from the Internet delivery side. It
represents a basis for further development work which may result in a complete technical
specification for carrying DVB content across P2P networks. Such a specification may be produced
in due course (although currently there is no plan to do so).
Extracts from the DVB P2P Commercial Requirements document are reproduced in Appendix 2 of
this document.
In producing this document, the EBU representatives played a significant role.
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18.7.2 DVB Study Mission on Internet TV Content Delivery
In March 2009, DVB decided to launch a major technical Study Mission on Internet TV Content
Delivery. The rationale for this study mission was mainly to investigate technology options to
deliver DVB-type content over the Internet to a large number of CE devices (including game
consoles), PCs or mobile devices. The primary purpose of the study was to identify if DVB should
start any specification activities in the area of Internet-TV content delivery, complementary to the
previous DVB work on managed and QoS-guaranteed IPTV delivery. Another key question was
whether or not DVB members consider P2P as an appropriate technology for media delivery over
the Internet, so that they could start a standardisation process.
In the light of a large number of responses received, the Study Mission showed that many DVB
members, including broadcasters, CE manufacturers, technology integrators, network providers and
others, are already actively involved in the open Internet-related commercial activities and are
therefore highly interested in furthering the specification activities.
Based on the extensive information collected by the Study Mission report [26], many important
conclusions were taken, however for the purpose of this report we extracted the following items:
DVB should continue considering specifying of certain important Internet-TV content
delivery interfaces, formats and protocols. Most importantly, there is considerable scope for
improving technologies for the reliable distribution of high-quality commercial AV content
over the Internet to a large number of consumer end devices, which requires considerations
that are not already sufficiently addressed by any standardization organization. Proprietary
solutions exist but are generally not targeted or adapted to typical DVB services, content
and end devices.
DVB should focus on components that have clear and well-specified interfaces, and can be
integrated and deployed in different end-to-end specifications and deployments and in
combinations with different technology components already specified by DVB or elsewhere,
such as service discovery, middleware, content protection, etc.
DVB should reuse technologies within the existing DVB specifications in areas of, for
example, DVB-IPTV, DVB-AVC (Audio Video Coding), DVB-FF (File format) and DVB-GBS
(Generic Data Broadcasting and Service Information Protocols), but only to the extent that
those technologies are well adapted and may potentially improve performance or/and add
functionalities, if deployed.
DVB should adopt an evolutionary concept of refining Internet-TV specifications in different
phases. Specifications of Internet-TV content delivery can be refined and extended more
easily than traditional broadcast specifications.
Internet-TV Content Delivery in mixed Broadcast/Internet deployments where the main
service is still distributed over DVB-S/T/C or IPTV. Specifications for the delivery via the
Internet of supplementary services such as content download, content on-demand or
auxiliary services should be considered initially.
No technical indication has been given during the Study Mission why the MPEG-2 TS and the
DVB AVC codecs could not be used in the Internet-TV content delivery. However, due to the
lack of QoS support, typically resulting in varying bitrates, adaptive content delivery for
streaming and download should be considered, along with suitable application and service
In Internet-TV content delivery HTTP is considered as the primary protocol from the network
to the consumer end device. DVB should investigate if such an approach can fulfil the
commercial and technical requirements for the use cases and services as initially considered
by DVB.
The Study Mission has found evidence that a classical client-server approach can efficiently
be augmented by adding caching servers - Content Distribution networks (CDNs), distributed
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across different Internet domains and located at the coverage edges. DVB should consider
this option in its initial release and attempt to standardise the interfaces and protocols
between the CDNs and the end user CE devices connected to the Internet.
Extensibility of the initial versions must obviously be taken into account from day one and
for this purpose relevant use cases should be considered and checked for possible
integration in later releases. Optional extensions should be considered, in particular
augmenting the specification with P2P-based delivery and/or combined CDN/P2P solutions.
DVB should focus on technical specification for the interfaces to the consumer end device,
as it has done successfully for all other broadcast systems. DVB should not duplicate its
efforts with other organisations such as OIPF, HbbTV or MHEG-5 IC, but should attempt to
provide sufficiently clear interfaces such that the existing specifications can be integrated in
emerging solutions. For example, an interface solution for a DVB Internet-TV technology
may be part of a Interactive TV offering just as existing DVB-T or DVB-S is.
Due to lack of time, the Study Mission report could not provide in-depth considerations of
some recent Internet-TV content delivery developments, such as those specified by OIPF,
DVB CDS Unicast, Apple and Microsoft IIS-Smooth Streaming. Nevertheless, these
specifications could provide a sound starting point for preparing DVB technical specifications
for Internet-TV content delivery.
As shown by the numerous inputs to the Study Mission from NextShare, Samsung P2P-TV and
emundoo as well as the work in the IETF on PPSP, the DVB Internet-TV specification could
be usefully enhanced by adopting an optional standardised P2P interface.
For our purposes, the statements referring to P2P delivery are highlighted in italics. The message
given is that the DVB Consortium does not exclude considering the P2P delivery, either independent
or in combination with CDN, and may develop the appropriate P2P protocol and interface
standards, provided that the market requires them, as optional additions to the DVB Internet-TV
18.8 Use of SVC/MDC (Scalable Video Coding/Multiple Description Coding)
in P2P Systems
The advantages in terms of robustness, reconfigurability and scalability make P2P a promising
technology. The P2P approach permits to serve a larger audience without the need of
proportionally increased resources; in fact, only a small fraction of the audience should be served
directly by a content provider. Users may then connect to each other and exchange their content.
From the user point of view, the P2P should allow to experience high quality video in a cost
effective fashion.
A P2P client (node) usually receives data from many peers simultaneously, only partially relying on
centralized servers. All peers provide the community with resources in terms of upload bandwidth
and storage capability. The distributed nature of P2P overlay networks increases robustness in case
of failures, as data are usually replicated over multiple peers. On the other hand, the use of P2P
for video distribution is not devoid of problems. Real time streaming applications require the
overlay network to guarantee a constant flow of data and low start-up latency, as well as on-the-fly
content adaptation and inherited resilience. The P2P video technology still experiences problems of
long start-time and churn-induced instability. The aggregated peer uplink bandwidth is still
typically insufficient to support large scale distribution, due to the asymmetry of residential
broadband connections. Packets losses happen for several reasons: router congestion and
transmission errors on the physical network, node departure from the P2P overlay, strict timing out
due to real time visualization (which makes data packets lose relevance very quickly). The lack of
guarantee about the actual delivery of the data may cause unacceptable drops in the reproduction
quality, and frequent service outages. For example, due to predictive encoding, a packet loss not
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only corrupts the current frame in a video transmission, but the error also propagates to
subsequent frames. Another relevant aspect that is affecting research in multimedia is unreliability
and heterogeneity. Internet is a best effort network, with no guarantee about the actual delivery
of the transmitted data. Typically data get lost because of router congestion or transmission errors
(especially over wireless channels). In a P2P system, the vulnerability is also due to node departure
from the overlay network. In applications such as file download or web browsing, specific transport
mechanisms request the retransmission of the lost data; however, these cannot be used in a
streaming context, due to time out and network flooding problems. Needless to say, data losses
often cause an unacceptable drop in the reproduction quality perceived by the user, and frequent
service outage. Moreover, we expect for some years to come a communication scenario where a
user can access information in a seamless way, using terminals with very different characteristics in
terms of resolution and bandwidth, and different access technologies, ranging from DSL, WiMax,
GPRS/UMTS and so on. The demand for mobility and ubiquitous access poses stringent challenges,
because of the use of low power terminals and unreliable access networks.
Even though these problems are intrinsic in the P2P paradigm, some countermeasures can be
adopted at the video coding level. To this end, scalable video coding (SVC) can be an interesting
tool. In fact, different levels (layers) can be recovered from a scalable video stream, provided that
some basic information (the so-called base layer) is received. This helps avoiding abrupt service
breakdown, and also facilitates the exchange of contents among users equipped with different
display resolution. The following SVC modalities are possible:
Temporal scalability refers to the fact that one can decode a video streaming at different frame
rates according to decoding capabilities. The scalable stream can offer a base layer coded at low
frame rate and one or more enhancement layers with increasing frame rates.
Figure 19: Scalable Video Coding - Base and Enhancement layers
Spatial scalability is obtained when a video is coded at multiple spatial resolutions. The embedded
stream can offer a base layer at QVGA resolution with the possibility to scale up to full HD
according to the number of decodable layers. The data and decoded samples of lower resolutions
are used to predict data of higher resolutions in order to reduce the bit rate to code the higher
SNR/Quality/Fidelity scalability can also be exploited in order to increase the visual quality of a
video streaming. A coarse-quality version of a multimedia stream could represent the base layer for
preview and free-of-charge distribution with the capability to shift to high-quality resolution for
editing, post-processing and pay-per-quality services.
The different video layers can be transmitted in different bit streams called sub-streams or they
can also be transmitted in the same bit stream, which is called an embedded bit stream.
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Figure 20: Spatial and SNR scalability
A major boost to scalability is given by the MPEG/ITU-T JVT H.264/SVC co-decoder [19]. It is
conceived as an extension of H.264/MPEG-4 Part 10 AVC [20], [21] and it implements temporal,
resolution, and quality scalability and any combination of them, with limited compression penalty
with respect to AVC.
As for P2P, SVC is a very promising technique given that it is possible to guarantee the correct and
timely delivery of the base layer, through centralized servers or a reliable network infrastructure.
The peers would then be able to improve the visual quality by decoding enhancement layers
received from other peers. SVC can be used to serve clients with different requirements (e.g., low
quality and low bandwidth, high quality and high bandwidth), e.g. through application layer
Multicast, with every layer being served to a different Multicast group, and users joining as many
groups as desired. SVC requires that the base layer be delivered with very high reliability, and this
calls for suitable error control or scheduling techniques.
At the moment, P2P clients do not have the capabilities to store scalable content nor to exchange
different layers of a given content. Moreover, another open issue is how to define a scalable
stream, in terms of the number and type of layers, and the rate devoted to each of them.
H.264/SVC, for instance, only standardizes the bit stream syntax in order to allow a decoder to
successfully decode a scalable stream. It is thus possible to develop non-normative tools at the
encoder-side to generate such a bit stream.
The number and type of layers, as previously explained, should be carefully tuned in order to avoid
inefficiency of the system together with a proper and jointly rate-distortion optimization. Given
two resolution layers (i.e. QCIF and CIF), it is still an open question how to distribute rate among
these layers. The rate-distortion optimization may become even more sophisticated in case of many
Multiple Description coding is another coding tool that is gaining popularity in the video coding
community. In the MDC approach two or more representations of the same data, or descriptions,
are generated, which yield mutually refinable information and can be independently decoded.
Descriptions are created so that the quality of the recovered signal is only a function of the number
of received descriptions.
Similarly to SVC, MDC allows for graceful degradation, in that a basic quality level is obtained from
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a single description, and quality enhancement stems from the decoding of further descriptions.
Different from SVC, which requires the reception of the base layer, no hierarchy exists among
descriptions, so any description is useful to improve quality.
The benefits of MDC features are paid for in terms of some impairment of the compression
efficiency, due to the inserted redundancy among the descriptions. This redundancy is generally
measured in terms of the extra rate required by the MDC scheme, compared to a single description
reference system achieving the same performance.
Figure 21: MDC versus standard encoding, quality frame-by-frame with 10% packet loss.
The black line corresponds to standard coding protected by Reed-Solomon forward error correction
(all-or-nothing behaviour), the blue line corresponds to two descriptions (slightly lower average
quality, but much lower variance).
Descriptions must be somewhat correlated to each other, so that the lost information of the
missing descriptions can be estimated from the received descriptions. As the redundancy is
detrimental in the case of error free transmission, it is clear that the number of descriptions and
the related redundancy should be carefully tuned in order to match the actual network conditions.
Several MDC techniques have been proposed, such as MDC quantization, correlating transforms,
lapped orthogonal transforms, correlating filter banks, video sub-sampling and Reed-Solomon
forward error correction. The interested reader may refer to [22] for a detailed tutorial on this
topic. Recently, MDC schemes have been proposed that are compatible with coding standards such
as JPEG2000 or H.264/AVC. H.264 options such as redundant slices and FMO, are exploited, for
example, in [23], to create two H.264 streams, which can be either separately decoded, or preprocessed prior to be input to a standard decoder. This latter algorithm which makes use of the
redundant slice option present in H.264, generate two descriptions, each of which contains some
primary and some redundant slice representations. At the decoder side, the finest representation
of each slice is retained. Even though it is subject to the drift effect, the algorithm has proven to
yield good performance, with little extra complexity with respect to H.264 co-decoding.
One of the objections to the use of MDC in P2P is that peers receiving a subset of the descriptions
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generally recover only an estimated version of the missing ones; consequently, peers may be called
to share non equal contents. This drawback has a few possible solutions, and is also relevant to
SVC. However, it is worth noticing that MD schemes allowing for exact reconstruction of the signal
do exist. In MDC using redundant bases (frames), the descriptions, obtained as the output of an
oversampled filter bank, exhibit deterministic redundancy and enable exact recover of missing
information. As such descriptions are generally visually meaningful, they can be individually
compressed using standard tools; this way, the description generation and decoding can be
conceived as pre-/post-processing tools at the transmitter/receiver. Moreover, as MDC exploits
diversity in the network path from the server to a client, such diversity must be provided. One way
to do so is to employ a multiple-tree architecture. Mesh-based overlays should also employ some
form of path diversity, e.g., multiple meshes.
Interesting research topics regard the comparison/merging of MDC and SVC features, and the
adaptation of MDC tools so as to create scalable descriptions. Another issue is the relationship
between MDC, SVC and distributed video streaming, which makes use of the distributed source
coding principles for efficient encoding of correlated sources (e.g. different resolution versions of
the same video).
SWOT Analysis of P2P Systems
The following section gives a bulleted SWOT analysis from the broadcasters’ perspective:
19.1 Strengths
very effective for broadcast (one-to-many) mass distribution – compared to Unicast
cost effective – processing and storage resources contributed by the users
low infrastructure requirements for ‘broadcasters’
low barrier to entry by new CPs leading to an enrichment of the content industry and
greater consumer choice
‘network edge solution’ - no need to upgrade the Internet to embrace new technologies – a
problem faced by technologies such as IPv6, Multicast, etc
software-only solution - no specific hardware required at the clients' end
distributed solution - less sensitive to congestion, node failures,...
global reach, equivalent to the reach of the Internet
supports content download, progressive download and live streaming (ideally the same
client software)
scalability – so long as stream bandwidths are < average (upload capacity)
P2P client could be embedded in the CE devices and mobile/portable devices
can be integrated in hybrid (P2P/CDN) systems
19.2 Weaknesses
relies on a ‘neutral’, open Internet that does not filter out specific types of content
relies on the ‘generosity’ of users to share their resources as part of the commons
leeching behavior is possible
an open door to content piracy if not administered
audience measurement difficult
content distribution control difficult (for fully decentralized P2P systems)
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content search and discovery difficult (for fully decentralized P2P systems)
tends to require a symmetric access to the end-user, which is not the case for broadband
Internet today (uplink 1/5th to 1/10th of downlink capacity)
relies on firewall puncturing strategies for a wide variety of devices (in order to optimize
sharing and efficiency)
special software has to be installed on client platforms if no plug-ins are used
best effort delivery (Internet property)
latencies of access to VoD and Live streaming content are very high (often in the order of
10-20 seconds) as compared to the near instant access properties of modern Unicast
19.3 Opportunities
new distribution channel (either complementary to traditional satellite, cable and
terrestrial) or standalone, for professional content
distribution opportunity for user-generated content – everyone can become a content
extend the reach of content to new communities such as younger target audiences and
geographical locations
distribution costs lowered substantially
accessibility to new market players – new business opportunities, increased competition
network neutrality trend can help protect the political and legal context for P2P
In line with the participation/conversation trend on the Internet through lowered barrier to
the public already relies heavily on P2P technologies. P2P content represents 10% to 50% of
the overall Internet traffic today
P2P may be a means to force ISPs to enable Inter-domain Multicast
with an increase in untrustworthy content providers the strategic advantage arising from
credibility of public service providers becomes even more important.
growth in uplink capacity tends to be more sustainable than growth in video bitrate due to
ISPs may migrate customers to symmetric access products (by tiering services with the
promise of HD on-demand) leading to higher ARPUs and other downstream opportunities
an open public platform which no one company can control or switch off
19.4 Threats
More competition on the content market since almost any individual or organization can
afford delivery for modest cost.
regulation could ban peer-to-peer technologies due to bad reputation in relation to content
ISPs could slow down or block P2P traffic to prioritize their own solutions (like Multicast) or
reduce traffic travelling over their infrastructures
the media industry has a natural tendency to expect precise audience metrics for Internet
applications, although it was never the case for traditional TV and Radio
longtail trend: the attention goes towards niche content and less towards mass media.
gatekeeper role of broadcasters and media organizations could be weakened
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CDN providers and ISPs may integrate P2P technologies which may become opaque to
broadcasters, growth in efficiency may benefit ISP/CDNs only
Greater piracy leads to crisis in intellectual property conservation and recession of creative
industries in general.
Main Challenges and Open Questions
This section gives a short list of some important study and research topics which need to be
considered before P2P services come into regular operation. The list is neither complete nor is it
20.1 Efficiency
What is the benefit of P2P compared to Unicast in terms of bandwidth saving?
Some P2P solutions use all available upload capacity that a user disposes. For example, if a peer
gets a radio stream at 200 kbit/s and have a 20 Mbit/s upload capacity line (say, at work), a P2P
solution could use the whole upload capacity of the 20 Mbit/s, thus sending streams to 100 other
peers. This approach is typically taken by traditional P2P solutions, where P2P is seen more like a
simple distributed server setup. Many newer P2P solutions however have default behaviour by
which upload and download for each individual peer is more balanced and takes into account only a
portion of upload capacity that is really needed.
Some P2P solutions use capacity from ‘passive peers’, namely the peers which do not actively
render (consume) content but could contribute to aggregate upload capacity. Such a contribution
could be fairly small; however, as the numbers of passive peers can be large, the total contribution
could be important.
In summary, efficiency of a P2P system depends on two elements: a) whether or not uses a totality
of upload capacity available or just a minimal portion of it, and b) whether or not it makes use of
upload capacity provided by passive peers.
This topic requires further study.
20.2 Upper bound/scalability
Is there an upper bound (i.e. maximum number) of concurrent users beyond which the P2P network
degrades or even fails to work properly?
P2P networks could be expected to scale to several millions of concurrent users. In principle, this
should be possible since each peer that joins the network increases the capacity of the network.
However, this theory ignores the real-life of available uplink and downlink bandwidth for each
peer. In practical xDSL networks downlink and uplink may be heavily unbalanced; their ratio could
be between 10 and even 20. This means that uplinks could get saturated 10 times earlier than the
downlinks. Consequently, the number of uploading peers should be at least 10 times greater that
the number of downloading peers. If the number of downloaders is the same as the number of
uploaders, then the average download capacity is limited by the average uplink capacity.
For live P2P streaming of high quality streams, the imbalance and saturation represent a significant
challenge in delivering full quality to all participants. The instantaneous upload capacity is the
constraint. It is still possible to serve all peers but with lower quality. A possible solution is to use a
hybrid P2P/caching approach, where distributed caches are used to seed streams into the P2P
Analysis of optimum relationship between P2P and caching for a given network is required.
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20.3 Network Topology
The P2P networks can have either a tree or mesh (grid) topology or indeed a mixture of the two. A
study of pro’s and con’s of different P2P network topologies is required in terms of efficiency,
latency, reliability and other technical parameters.
20.4 (De-)centralization balance
A P2P network can have different degrees of centralized and decentralized (distributed)
functionalities for media (video, audio, data) distribution and control/management data.
Considering BitTorrent-type tracker control/management functionalities, they can be either
centralized in a central server, or distributed across peers or indeed a combination of the two.
Is there an optimum balance of centralization or decentralization of the P2P network?
20.5 Latency
As the signal propagates through the network, there may be some significant delay in accessing the
streams. Latency is the time that elapses from injection of input signal in the encoder to rendering
at the end user device. P2P delivery often occurs over several hops; however, as ping times on the
Internet are down to a few milliseconds such extra hops do not significantly degrade latency. The
main source of latency is the need for extra buffering which may amount to several tens of seconds
(typically between 20 to 30 s) up to several minutes.
Latency is a general Internet distribution problem and not specifically P2P-related problem.
20.6 Service reliability (QoS)
Internet is a best effort, no-QoS environment. There is no guarantee for service quality in terms of
service interruptions, discontinuities, dropouts. Typically these occur due to buffering, traffic
congestion, jitter, packet loss, etc.
Specifically, P2P quality may suffer due to clients opting out (the tree-type of P2P is more fragile
than the mesh-type P2P). A possible remedy to poor quality of P2P system is to use an ‘intelligent’
plug-in/application to be installed at the end user PC. A plug-in could control whether or not
content has been received and how well it has been played out (and not just sent). If there is any
service problem, the plug-in could try to access other sources on-the-fly and pick the best one.
The question is what other means to improve the quality of P2P services could be used? Would it be
possible to use FEC, packet retransmission and other measures often used in the Internet
20.7 Traffic Peaks
The ability to accommodate large traffic peaks arising, for example, at the start of major broadcast
events (such as the Eurovision Song Contest), is very important performance characteristic. It is
largely expected that a P2P system should be able to cope with sudden expected or unexpected
surges of traffic.
There are two problems.
a) Peak requests just prior to the event, and
b) Build-up rate capability (i.e. how fast the number of connected peers receiving certain
quality can grow after the start of the event)
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a) In traditional solutions using a central server, bottleneck problems can arise when many client
requests are arriving in a short timer interval. A P2P system can be designed in such a way as to
spread the instantaneous burden and find the best way to get the stream. This can be done by
distributing the ability to capture requests from the newly joined peers by the nearby peers that
are already members of the P2P network. In other words, a ‘plug-in solution’ embedded in each
client can help to spread a burden more evenly.
b) The build-up capability of the P2P network can be significantly improved by injecting several
streams at a number of locations at the same time. A hybrid solution consisting of special caching
servers or super-peers (along with P2P clients) could be helpful.
This topic requires further quantitative study.
20.8 Critical mass of peers
Ideally, P2P systems should be able to operate with a small number of peers. The question applies
what is the critical mass (i.e. a minimum of users) to make P2P viable?
20.9 Switching time
Zapping between TV channels in P2P environment can take several seconds, as only one TV channel
is transmitted at the same time. The problem of switching time may be quite severe, as most P2P
systems use long buffering provisions.
A study is required to shorten the channel switching time. Would it be possible to use the FCC (fast
channel change) approach, as used in IPTV?
20.10 DSL asymmetry
Clearly, P2P efficiency would improve if networks on which P2P is overlaid were more symmetric.
However, the reality of DSL networks is that upstream bandwidth is very low (for ADSL2+
asymmetry may be as high as 24:1). This problem may be partly resolved by using the principle that
the upload bandwidth would be proportional to the download bandwidth. In other words, the more
you download, the more capacity of your computer you should allow others for upload.
20.11 Large bitrate (HDTV) streaming
The question is how P2P networks could be able to handle real-time streaming of very high bitrate
streams, e.g. HDTV (typically, HDTV may require a total of 8 to 12 Mbit/s).
20.12 Geolocation
A geolocation provision is often required to satisfy copyright requirements. How can a
decentralized P2P system handle geolocation to cope with copyright?
20.13 Virus contamination
A P2P-type network is ‘ideal’ for fast propagation of viruses and spyware. What measures shall be
taken to prevent virus propagation? In cases where the prevention is not effective, how can a virus
be removed promptly and efficiently?
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20.14 Possible Blockage of P2P packets
This question is closely related to net neutrality. The Internet Service Providers (ISPs) are
confronted with the estimate that P2P traffic may consume up to three quarters of all Internet
bandwidth. This leaves very little room for other applications. In order to preserve subscriber
access to these applications, especially in peak times, some ISPs try to simply block (filter out) P2P
packets, thus disabling all P2P applications.
Fortunately, most of ISPs endeavour to identify more constructive solutions aiming at preserving
subscriber access to P2P services. ‘While ISPs are desperately seeking to reduce their spiraling
bandwidth costs relating to increased P2P traffic, they also recognize file sharing as a significant
driver of new broadband subscribers to their network services’.
(Michael Hoche, Aberdeen Group). The measures taken to save P2P may be multiple, ranging from
imposing download quotas, traffic shaping, ‘charge more’ and ‘least-cost routing’ to caching.
Additional caching can significantly reduce transit and network costs while maintaining the user
experience. However, there is some cost involved in installing and maintaining P2P cache servers.
Therefore the question applies as to which entities should share the caching costs, so that the
expected quality level of P2P services could be maintained and indeed increased.
Summary and Conclusions
Access to audio-visual content via Internet is an increasingly valuable resource to both citizens and
broadcasters. Over the last several years, traffic on the Internet has grown by more than 50% a
year. Distribution of audio-visual materials across the Internet has become an important activity
involving extensive investments in the Internet network infrastructure, end user devices and new
media-encoding technologies. As the creation and consumption continue to grow, the traffic
volumes will grow at an even faster pace. As the video files and streams are very large, the danger
is that the network load becomes unsustainable and the Internet may eventually collapse. To ease
the network load, novel distribution technologies are required. It has now become clear that the
centralised server-client approaches practiced by many network providers are no longer the only
viable proposition and that distributed models are rapidly developing to support more Internet
To this end, the Peer-to-Peer (P2P) system - as a representative of a decentralized, distributed
network architecture - continues to be an attractive solution for carrying media across the
Internet. P2P seems to be an attractive long term solution for the following main reasons.
P2P is an overlay to the existing broadband network and does not change the existing
network infrastructure
Relatively low service cost (per GB delivered) compared to Content Delivery Networks (CDN)
Low investment and maintenance cost
Scalability to millions of concurrent users
High service reliability
No single point of failure
Lower network load (compared to Unicast).
Today, a large number of broadcasters and portals are carrying experiments and operational P2P
services for downloading, VoD and streaming using several commercially available P2P systems.
However, these services are not compatible and are only available via PC. We need to develop a
standardised P2P solution which will enable access to all the content, services, applications and
end user devices.
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P2P is not the only solution for delivering content across the Internet. There may be situations,
where P2P is not the most suitable choice, and other delivery approaches may be more
appropriate. There are many challenges still to be resolved with P2P. The market reality is that P2P
is increasingly being used in conjunction with other delivery mechanisms such as CDNs, as opposed
to stand-alone P2P systems. These hybrid approaches are increasingly popular in the Internet
distribution market (examples: Octoshape going with CDNetworks, Joost moving to CDN, etc.)
It should be made very clear that the adaptive HTTP streaming approach is a very strong candidate
for content delivery, potentially displacing P2P from the no.1 position. However, it remains to be
seen how the promising technology will be converted into a viable market proposition.
Today, pure P2P systems are most successful at low bitrates (such as live radio/audio-only
streaming) but – due to asymmetry of today’s broadband networks – high-quality video broadcasts
(1 Mbit/s or more) are more challenging and require additional mechanisms (super peers, edge
caching, CDNs, etc).
P2P is most efficient for local, close area services but seems to be less suitable for inter-domain
services involving two or more different ISPs, especially if the broadband network is star based
(examples: the Netherlands, the UK).
Several P2P approaches have recently been refined (or are in the process of becoming more
‘intelligent’) in order to understand the broadband network topology, so that media flows can be
optimised (e.g. smallest number of hops, shortest latency, lowest transport cost, etc) – examples:
Octoshape, Tribler (NextShare). Such ‘intelligent’ P2P systems are potentially able to substantially
ease the network load and improve service quality, compared to traditional P2P systems (such as
BitTorrent, Kazaa, etc).
Intelligent P2P such as P2PNext libswift should be able to radically change the Internet distribution
market. Libswift is a promising P2P solution, which is lightweight, inexpensive and simple, so that
it can be smoothly integrated in any ‘thin client’ devices including mobile and portable devices. It
should ideally enable all players in the value chain to improve their services (win-win situation),
however, all players will need to adjust themselves to the new P2P paradigm (if P2P is
commercially successful). For example, in the light of commercial pressure and vigorous
competition, ISPs may wish to make their networks more symmetrical, offer higher download and
upload capacities, introduce flat rates and remove service caps (ceilings).
It is important to develop, test, standardize and market as soon as possible an ‘intelligent’ P2P
algorithm which is network topology aware. Such algorithms are being developed by the EC-funded
project P2P-Next, NAPA/WINE and others. These research projects include all constituencies
including broadcasters, operators, manufacturers, etc. and could provide a sound basis for the
system stack standardisation of advanced P2P approaches. The possible use of scalable video
codecs based on H.264 and specifically optimised for the use in P2P networks has been alluded to.
It has been shown that P2P can be implemented not only in PCs but also on low-cost consumer
devices. For example, Pioneer has already developed a first low-cost prototype P2P-enabled STB
which is able to perform live TV streaming. There are indications of significant interest among CE
manufacturers to develop prototype P2P-based devices –examples: Pioneer NextShare, Tribbox
(ST Microelectronics), AHT, etc. However, our expectations should be realistic – there is no
standardised P2P solution allowing the mass market deployment, as yet.
P2P has been implemented on an Integrated Circuit designed by ST Microelectronics (Tribler
algorithm). Any STB/TV set manufacturer is able to use this chip to market their products in the
open market.
In order to accommodate P2P-enabled CE devices in the market, there is a requirement to
standardise a P2P algorithm and other layers of the stack (e.g. video coding, middleware,
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metadata, signalling, etc). This document provides some reflections on how P2P could be
successfully introduced in the non-expensive consumer electronic devices and gateways.
The future P2P standard should be able to accommodate any business model (examples: flat rate,
various solidarity approaches, bandwidth as currency, etc.). Ideally, the same P2P standard should
be able to perform streaming, downloading, VoD, catch-up TV, etc.
The Digital Video Broadcasting (DVB) Project (in cooperation with the IETF) is undoubtedly the right
standardisation development body to agree the P2P standard for TV sets and CE devices. However,
the standard should be adopted at the appropriate moment, not too early and not too late.
Research into P2P has been underway for over 10 years and the R&D work is now mature enough for
the foundations of a standard to be created. The standard should be modular, expandable and
evolvable. Other international bodies involved in Internet media standardisation (such as Open IPTV
Forum) are expected to adopt the DVB approach on P2P, rather than develop their own approach.
It is important to understand the difference between PC-based P2P and CE device-based P2P
services. The latter may be constrained by a limited processing power and memory footprint,
upgradeability of software and introduction of new services. However, it should be pointed out that
the both PCs and CE products are becoming more and more powerful in time but the difference will
probably remain to keep the cost affordable.
P2P requires efficient audio and video codecs in order to minimise the bitrate of the stream.
Ideally, these codecs should be standardised, open, licence-free, and may become part of a
In order to overcome high asymmetry of DSL-type access networks, possible contributions of
‘passive’ or ‘stand-by’ P2P-enabled devices to the aggregate upload capacity would be highly
advantageous. It would be important to identify mechanisms which encourage users not to switch
off their devices when they do no longer watch TV programmes. Overall energy consumption of
potentially millions of such stand-by devices should therefore be minimized.
All Internet TV players should endeavour to establish a suitable legal framework which would
disallow unfair blocking or degradation of content, and prevent arbitrary discrimination against
particular providers of content, applications, services or devices. Internet service providers (ISPs)
play an important role in this effort and should be able to develop their businesses and obtain the
fair revenue streams for them (example: subscription, multi-tier service levels, etc)
P2P services should include accurate and timely audience statistics, information about the share
between CDN and P2P bandwidth (bandwidth saving due to P2P use), and the individual
contributions to aggregate bandwidth.
Building Communities: P2P is a ‘natural’ environment for building groups of users interested in the
same programme and willing to chat, share, communicate, invite friends (and friends of friends)
and help each other. Incentive mechanisms in the P2P environment are very important – people
should be encouraged to share content and contribute to the aggregate upstream capacity. Each of
them can become a broadcaster.
P2P can be used not only in totally unmanaged open Internet environment but also in a closely
managed environment by using a transaction server controlling the database of all users, all
transactions, all content and metadata. In fact, there are indications that commercial system
would always require some degree of system management.
A vision of an ‘Open Service Sphere’ platform that can be globally used to develop any application
of user interest is now being promoted by the European Commission [24]. Such an open service
platform will integrate innovative web-based services, sensor networks, mobile networks and cloud
computing platforms to develop new business applications in the Internet. It goes without saying
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that P2P-based network technologies may provide a suitable technology framework for such a
In the past P2P protocol has been tainted by its association with copyright piracy. Many detractors
still associate P2P with illegal file sharing. It is now high time to remove this bad name and
consider P2P a suitable legal mechanism for transport/distribution of legal TV/video content. All
content-related copyrights should be cleared in advance to P2P broadcasts. A suitable Digital Rights
Management system should be used to enable the legal use of content.
We should be aware that P2P is not a universal distribution panacea. It will not replace
conventional satellite, terrestrial and cable delivery mechanisms. It will rather complement them
when and if appropriate. In the most likely future scenario, P2P technologies will be used in
combination with the CDN, IP Multicast and adaptive HTTP streaming solutions for efficient,
reliable and high-quality distribution of audio-visual content across the Internet.
In concluding this report, we should state that it is presently not possible to take a clear-cut
position in favour of using P2P for all purposes. It is not possible to recommend P2P as a single best
solution without any reservations. There are many excellent solutions now available in the Internet
media distribution market, and there is a good prospect of more solutions to come in the near
Discovering P2P : Michael Miller, Sybex, San Francisco, 2001
From P2P to Web services and Grids – Peers in a Client/Server World : Ian J. Taylor, Springer-Verlag London,
Eric Klinker: When should you choose P2P?, Streaming media Magazine, September 2008
Enabling Digital Media Content Delivery, Emerging Opportunities for Network Service Providers, Strategic
White Paper, Velocix – An Alcatel-Lucent Company, March 2010
On peer-to-peer (P2P) content delivery, Jin Li, Peer-to-Peer Networking and Applications, Vol. 1, No. 1. (7
March 2008), pp. 45-63.
Open Content Aware Networks (OCEAN), FP7 proposal, Networked Media & 3D Internet, Annex 1, January
Solving Open Internet Peer-To-Peer Content Distribution Using CE Home Devices (IBC 2008, 12. September,
How P2P Technology Can Change Broadcasting As We Know It (11. September, IBC 2006)
EBU Technical Review, July 2005: EBU introducing Octoshape — a new technology for large scale streaming
over the Internet
Hei X, Liang C, Liang J, Liu Y, Ross KW (2006) Insights into PPLive: a measurement study of a large-scale P2P
IPTV system. In: Workshop on Internet Protocol TV (IPTV) services over World Wide Web in conjunction with
WWW2006, Edinburgh, Scotland, May
S.M.A. Abbas, J.A. Pouwelse, D.H.J. Epema, H.J. Sips, ‘A Gossip-Based Distributed Social Networking
System,’ Enabling Technologies, IEEE International Workshops on, pp. 93-98, 2009 18th IEEE International
Workshops on Enabling Technologies: Infrastructures for Collaborative Enterprises, 2009.
Give-to-Get (G2G): Free-riding-resilient Video-on-Demand in P2P Systems: J.J.D. Mol, J.A. Pouwelse,
M.Meulpolder, D.H.J. Epema, and H.J Sips, Department of Computer Science, Delft
M. Meulpolder, J.A. Pouwelse, D.H.J. Epema, H.J. Sips, ‘BarterCast: A practical approach to prevent lazy
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freeriding in P2P networks,’ ipdps, pp.1-8, 2009 IEEE International Symposium on Parallel&Distributed
Processing, 2009
Towards an Incentive Mechanism for Peer-to-peer Multimedia Live Streaming systems: Thomas Silverstone,
Olivier Fourmaux, Jon Crowfort, International Conference on Peer-to-Peer Computing 2008, Aachen, 8-11
September 2008
Standby Power Consumption for 2008 Philips TVs,
P2P-Next Deliverable 5.3.1 – Tools for Rich Metadata and Signposts, Michael Eberhard (UNIKLU) et al,
December 2009
Net Neutrality in Europe, Neelie Kroes, Vice president of the European Commission Commissioner for the
Digital Agenda, Address at the ARCERP Conference (L’Autorité de Régulation des Communications
Electroniques et des Postes), Paris, 13 April 2010
P4P Provider Portal for Applications, Haiyong Xie et al, SIGCOMM 08, August 17-21, Seattle, Washington, USA
ITU-T Rec. H.264 Annex G/AVC Amendment 3, Scalable Video Coding (SVC), January 2007
Joint Video Team JVT of ISO/IEC MPEG and ITU-T VCEG, International Standard of Joint Video Specification
(ITU-T Rec. H.264, ISO/IEC 14496-10 AVC), March 2003
T. Wiegand, G.J. Sullivan, G. Bjntegaard, and A. Luthra, ‘Overview of the H.264/AVC video coding
standard,’ IEEE Trans. on Circuits and Systems for Video Technology, vol. 13, no. 7, pp. 560–576, July 2003.
V. K. Goyal, ‘Multiple description coding: compression meets the network,’ IEEE Signal Processing Magazine,
Vol. 18, Issue 5, pp. 74 – 93, Sept. 2001
T.Tillo, M. Grangetto, G. Olmo, ‘Redundant slice optimal allocation for H. 264 multiple description coding,’
IEEE Transactions on Circuits and Systems for Video Technology, Vol. 18, No. 1, pp. 59-70, Jan. 2008
Future Internet – the way forward, Neelie Kroes, Vice president of the European Commission Commissioner
for the Digital Agenda, Future Internet assembly, Valencia, 14 April 2010
Freenet – A Distributed Anonymous Information Storage and retrieval System: Ian Clarke, Oskar Sandberg,
Brandon Wiley, Theodore W. Hong, published on July 1, 2000, available from
Digital Video Broadcasting (DVB): Internet TV Content Delivery Study Mission Report, DVB Document A145,
December 2009
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Appendix 1: Functional and Operational Requirements
for an EBU P2P System
(Guidance for P2P System Developers)
The ‘EBU P2P system’, hereafter termed as ‘EPS’, will be used by EBU members for distributing
their streams and files across open Internet.
EBU Members can use EPS for the following purposes:
live streaming
on-demand archive files distribution to individuals
progressive downloading and on-demand streaming
narrowcasting/podcasting (pushing content to selected groups of users/subscribers)
Example Usage Scenarios
This section gives some examples of usage scenarios, as follows:
streaming of live radio or television events (simulcasting)
downloading archive files after live events
viewing/listening only, no storage possible
progressive downloading of high-quality content
downloading and re-distributing of files to all users over the public Internet
downloading and re-distributing of files to other members in a private Internet network
after a file has been acquired, usage can be restricted in terms of time, location and
number of devices
applying rights management to files and streams
applying various billing mechanisms
applying social networking mechanisms
Basic System Requirements
The following are some basic requirements for EPS.
The EPS system refers to the transport mechanism only. Data about the programmes (e.g. EPG type
data) will be available in the same way it is available now (e.g. Media channels, websites, etc.) The
transport mechanism should be Codec agnostic.
shall be based on an open source approach
shall support all platforms, i.e. operating systems such as Windows, Mac and Linux and
browsers such as IE, Firefox and Opera
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should not hamper or disrupt users' PC or any existing applications (Java, etc)
should be capable of distributing both files and streams
should be easy to install on user's machine and should not require administrative rights
servers should be made available to any EBU member who requires it
should be highly scalable, resistant to peaks and ‘tails’.
should be able to cope with virus contamination
should allow for quasi real-time delivery (i.e. latency should be reasonable (below 1 min))
End User License agreement
Not necessary. However, for tracking purposes EUL would be a useful mechanism for a broadcaster
to be able to authenticate and track its users.
System plug-in requirements
When turning the computer on, the EPS plug-in should be automatically launched.
EBU EPS icon should appear in the task panel, as soon as EPS application is launched
EPS can be started from the ‘start’ menu.
EPS should support a range of video/audio players: WM (optionally also Real, QT and Flash)
EPS MMI (Management Interface) should be a media player.
Plug-in settings should be simple and available on ‘right-click’ of EPS icon
Any EPS updates should be performed on in a user-transparent manner
EPS should be able to apply a DRM system to control media access
For copyright, a geolocation system should be used on the fly to contain access to a given territory.
This system should be transparent to the user.
Geolocation systems may be distributed across the EBU zone in order not to delay propagation of
Other Broadcasters' Requirements
Broadcasters should be able to track the usage of streams/files (who is connected, how
long, which channel)
Downloading of EPS plug-ins should be ‘easy’ and scalable (the latter is important for live
Broadcasters should be able to apply GEO or not - depending on content rights issues.
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Appendix 2: DVB requirements of P2P
The following extracts have been taken with permission from the DVB IPTV 0442 rev15 document
(June 2009).
Internet-TV Content Delivery Architecture
As depicted in the Figure below, a P2P Internet-TV Content Delivery system is composed of several
P2P Clients are network elements which share AV files and/or streams among themselves
rather than receive them from a central server. They are typically embedded in Internet-TV
devices and work in best effort mode. Typical products are STBs, TV sets, media-enabled
PCs, etc. Primary goal is to have the P2P client in the Internet-TV device, but it is not
excluded that network equipment can host that function. It could also be part of a managed
device connected to DVB-IPTV managed system. In this case the P2P Client is still assumed
to operate in best effort mode.
A P2P Tracker23 is a central element hosting dedicated features and is under the control of
the Internet-TV service provider. The P2P tracker coordinates transfer of content (being
files or streams) among the P2P Clients. For instance the P2P tracker maintains information
about all P2P clients either uploading or downloading data. It may also track which segments
of content each P2P client stores, in order to assist in efficient data sharing between
clients. A P2P tracker can be centralised or geographically distributed across the network.
A P2P Auditing Server is a logical element under the control of the Internet-TV service
provider and hosts system and network monitoring functions. The role of the auditing server
is to provide data that reflects the operational status of the system. Its role is similar to the
RMS in an IPTV system.
A P2P Portal is a portal which allows the user to connect to many trackers using a single
logon facility. A user registers his/her P2P Internet-TV device with the supported Portal –
providing information, possibly including user-ID, user name, address and billing details. The
P2P Internet-TV device automatically downloads a list of channels provided by different
trackers from the portal without logging into all of the trackers. Users select a service from
a provider that has an agreement with the portal and are able to buy and consume services
from that provider without having to separately register, logon and provide personal details
to that provider-related tracker. The portal provides APIs to both P2P Trackers and P2P
Clients. A P2P Client does not need to modify anything when a new tracker is added.
Some P2P systems are trackerless, all metadata information is distributed among P2P clients.
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P2P Internet-TV
P2P Internet-TV
P2P Internet-TV Service-A
P2P Internet-TV
P2P Internet-TV
P2P Internet-TV
P2P Internet-TV Service-B
P2P Internet-TV
P2P Internet-TV
P2P Internet-TV Service-Z
P2P Internet-TV
Figure 22: Notional P2P Internet-TV Content Delivery system architecture (Courtesy: DVB IPTV)
The P2P Internet-TV Content Delivery system includes 5 types of interfaces which are proposed to
be standardized, as follows:
P2P Client / P2P Client
P2P Client / P2P Tracker
P2P Client / P2P Auditing Server
P2P Client / P2P Portal
P2P Portal / P2P Tracker
The P2P Internet-TV device may be owned either by the user or by the Internet-TV service provider
who rents it to the user.
The P2P Internet-TV Content Delivery system deals with content delivery and is widely agnostic to
other technologies such as e.g. Content Protection, audio/video codecs, content related metadata,
interactive middleware, service signalling, etc.
The technical group should give feedback on potential interdependencies, so that work in the
commercial group can be prioritized accordingly.
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Commercial Requirements for P2P Internet-TV Content Delivery
This chapter provides commercial requirements for P2P Internet-TV Content Delivery.
General requirements
The P2P Internet-TV Content Delivery system shall not assume any specific requirements from the
DNG for a successful operation.
The P2P Internet-TV Content Delivery system shall be compatible with both bridged and routed
Internet access.
The P2P-Internet-TV Content Delivery system shall allow various types of applications such as
CoD (streaming, progressive downloading and deferred downloading)
Live streaming of TV / Radio events and channels
It shall allow for both traditional content and lawful user generated content.
: For the user the services may look similar to the related IPTV services, but QoE might be lower.
The P2P-Internet-TV Content Delivery system shall not impose any limitation on the content format
(coding, resolution, frame rate, etc). Subject to P2P network capabilities, carriage of large streams
and files (e.g. HDTV) should be enabled.
: Internet-TV services might provide lower QoE than managed IPTV services.
It shall be possible to distribute content (or pieces of content) using typical content delivery
networks based on servers only (e.g. CDN). In other words, the P2P Internet-TV Content Delivery
system shall be able to interface with CDNs. If the P2P system faces extremely severe circumstances
(e.g. lack of suitable peers), it shall be able to fallback to CDN mode.
The P2P Internet-TV Content Delivery system shall scale in terms of number of users. It shall not
impose any limitation in terms of maximum number of concurrent users.
: Please consider commercial TV services deployed over the Internet as examples for the typical
number of users.
The P2P Internet-TV Content Delivery system should be able to support abrupt increases in the
number of peers that may occur at the start of live TV streaming events when potentially large
numbers of users may wish to connect and start watching the event.
The P2P Internet-TV Content Delivery system shall support a fast response to user requests for
content delivery and content presentation, especially for live streaming.
: QoE with Internet-TV is expected to be lower than with IPTV.
The P2P Internet-TV Content Delivery system shall not prevent the delivery of complementary
streams such as subtitling, spoken subtitling, audio descriptions and signing, in order to provide
value-added services and satisfy requirements of different interest groups.
The P2P Internet-TV Content Delivery system shall support high QoE for the user.
The P2P-Internet-TV Content Delivery system shall not preclude the usage of geolocation data.
Note: Geolocation means that service availability depends also on the geographic position of the
The technical group is requested to consider the existing P2P protocols that are currently widely
used on the Internet as a technical basis for P2P Internet-TV Content Delivery system.
Effort should be made to align with other IPTV security related DVB requirements and specifications,
and build on them.
The P2P Internet-TV Content Delivery system shall not prevent the implementation of a secure
transaction mechanism allowing pay TV or free-to-view content to be provided according to usage
guidelines defined in the DVB CPCM commercial requirements.
Within the P2P Internet-TV Content Delivery System channel zapping time shall be minimized.
The P2P Internet-TV Content Delivery System shall support seek operation based on time, allowing
the user to move to a relative or absolute time of playing position.
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The P2P Internet-TV Content Delivery System shall not prevent content providers from delivering
user created contents.
The P2P Internet-TV Content Delivery System shall support using DVB EPG (or BCG) to locate the
P2P-delivered channels.
The P2P Internet-TV Content Delivery System shall allow content providers to update their services
(including title, description and content) without terminating the service.
The P2P Internet-TV Content Delivery System shall not prevent the user from accessing multiple
services from different portals at the same time.
P2P Internet-TV Content Delivery Management
This section captures the requirements on the P2P Internet-TV Content Delivery system from the
Service provider point of view.
Storage usage and management
One of the key points in a P2P Internet-TV Content Delivery is the level of replication for the
various pieces of content. When a content item is highly replicated, QoE may be satisfactory. When
a content item is rarely replicated on the network, QoE may be poor. Therefore, one of the key
success factors of a P2P content delivery system is the capability to guarantee a certain response
level of the system. A P2P content delivery system will behave well, once a given content is
sufficiently replicated within its peers.
For instance, when a new content is introduced in a P2P content delivery system, it is available at
only a few peers. Therefore, as long as it is not sufficiently replicated, the response level of the
P2P content delivery system may be quite weak. One way to solve this problem is to allow a service
provider to manage the content replication, in order to be able to reach the required objectives in
terms of the response levels.
In order to achieve this, the storage available in the P2P client is modeled in two logical distinct
areas, one under the control of the user where he can manage content (e.g. save/delete), called
the user storage area; one under the control of the P2P-Internet-TV service provider, called the
service provider storage area.
Different business models are envisaged and it is up to the service provider to decide whether he
requires two distinct storage areas or not. So, the support of two storage areas is optional, but may
be required by some service providers for implementing their services.
This section provides requirements, so that a service provider can use and manage the storage that
is available in a P2P system. These requirements apply to both the user storage area and the
service provider storage area.
The storage in a P2P Internet-TV Content delivery system may be divided into two distinct
partitions, user storage area, where the user can download, save and delete content; and a service
provider storage area, where the P2P Internet TV Content Service Provider can download and delete
content from. Business models shall be supported that have either one or both storage area present
in the ITD.
: It is envisaged that for live streaming services, a separate storage area in the ITD will be used
temporarily during the streaming session, the size of which shall be defined at the P2P installation
An ITD supporting P2P content delivery as well as other download services such as CDS shall be able
to support separate storage areas for each download service.
Content on the user and service provider storage areas shall be available to the P2P Internet-TV
Content Delivery system, i.e. other peers from the system shall be able to get content from both
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storage areas subject to access restrictions.
Service provider shall be able to manage the level of the content replication (or the replication of
content segments) in the service provider storage area to reach the required objectives in terms of
content presentation latency.
It shall be possible for the P2P Internet-TV Content Delivery system to find out the size of the total
storage capacity of the P2P ITD (independent of user and service provider storage areas). The
storage size information may be used to assess the suitability of the P2P ITD to participate in the
P2P Internet-TV Content Delivery system. The P2P Internet-TV Content Delivery system may reject
joining if the P2P ITD does not meet a minimum storage requirement.
The P2P system shall be able to query, create and resize P2P storage areas (user and service
provider) subject to access restrictions imposed by the user and/or ITD. This may be carried out via
a remote management system or via another mechanism.
It shall be possible to create and resize P2P storage area (user and service provider) via a user
interface subject to access restrictions imposed the service provider.
There shall be a mechanism allowing a P2P Client to receive updates to a content item, so that the
latest version of that content item is automatically available on the client.
It shall be possible to restrict access to content stored in both the user storage area and the service
provider storage area to authorized P2P clients..
It shall be possible to detect the tampering of content stored in both the user storage area and the
service provider storage area.
It shall be possible to restrict the ability to identify content stored in the both the user storage area
and the service provider storage area to authorized P2P clients.
An auditing system is necessary in order to monitor the performances of the P2P Internet-TV
Content Delivery system. This will require features to be supported in the P2P Clients as well as on
an Auditing server (see Figure).
It shall be possible to monitor and report relevant data of the P2P Internet-TV Content Delivery
system in order to get information on the operational status of the system.
: Possible data may include statistics on uploaded and downloaded data, up & down bandwidth,
play out errors, etc.
The P2P Internet-TV Content Delivery system shall be able to routinely monitor non-user-specific
information (e.g. global usage, statistics, network traffic, etc).
The P2P-Internet-TV Content Delivery system shall not preclude the use of audience measurements
mechanisms, such as measuring the size of the audience of a given event, possibly on the fly.
P2P Client management
The P2P Client shall be able to operate behind a NAT without a manual reconfiguration.
The P2P client shall be able to operate without a manual reconfiguration of a firewall and/or DNG.
The design should consider the need to conserve resources (e.g. ports) in the firewall, NAT and/or
The specification shall not preclude using several P2P Internet-TV devices on the same Home
The specification shall not preclude running several instances of the P2P client on the same P2P
Internet-TV device.
It shall be possible to define priorities between different P2P Flows. For instance, user requested
P2P Flows (CoD or Live) may have higher priority than background content placement &
management P2P Flows.
EBU Technical Report 009
P2P Technologies & Services
The P2P Client shall make its context information available to other P2P Clients or/and
Tracker/Portal (see Figure 1).
: Possible context information includes its IP address & port, its maximum uplink bandwidth, the
content locally available, etc.
It shall be possible to embed the P2P Client in a CE device, based on chip sets and storage, typically
used in high volume consumer digital TV devices.
It shall be possible to minimise free-riding by allowing P2P Clients to contribute some upstream
capacity when they are not actively used (e.g. a kind of active stand-by mode).
: The technical group is expected to make proposals which are compatible with low power
consumption modes.
Content acquisition and consumption
This section captures the requirements on the P2P Internet-TV Content Delivery system from the
user point of view.
When the user asks for a specific content on the P2P Internet-TV Content Delivery system, it shall be
possible to calculate the estimated start-up delay or download time.
The specification shall not preclude that manufacturers build devices allowing users to start several
Internet-TV services in parallel and that priorities for QoE can be handled.
Security requirements
P2P content security
The following content security requirements shall apply to the P2P Internet-TV system:
The P2P Internet-TV Content Delivery system shall allow detecting modifications of the content that
happened during its transport over the Internet and Home Network.
It shall be possible that only authorized P2P Clients can download certain content items.
The P2P Internet-TV Content Delivery system shall allow verifying consistency between the
downloading content and the metadata content title.
It shall be possible to prevent an eavesdropper from accessing content transmitted over P2P
Internet-TV Content Delivery system.
The P2P Internet-TV Content Delivery system shall support means to enable Service Providers to
detect illegal content in the system.
The P2P Internet-TV Content Delivery system shall not preclude the distribution of protected
content (including CA-protected, DRM-protected and CPCM-protected content).
EBU Technical Report 009
P2P Technologies & Services
P2P network security
As there is no work on network security in CM-IPTV so far, we ask the technical group not to
preclude inclusion of such technology in the system. DVB may decide later to start certain work in
this area.
The specification shall not preclude that measures can be taken, so that the P2P Internet-TV
Content Delivery system resists to Sybil24 and pollution25 attacks. In particular, this would mean the
unique identification and authentication of P2P Clients during a P2P session using secure
The specification shall not preclude that measures can be taken, so that the P2P Internet-TV
Content Delivery system protects the communications between P2P Clients and between a P2P
Client and infrastructure elements against unauthorized modifications. This includes both signaling
and content.
The specification shall not preclude that measures can be taken to detect overload of P2P Flows or
overload of Peers in case of malicious attacks (e.g. DoS26).
The specification shall not preclude that P2P Clients authenticate infrastructure elements from
which content is downloaded.
: It is open how authentication can be made in horizontal devices, not initially related to a service
User privacy
The overall P2P-Internet-TV Content Delivery system shall fairly preserve the user’s privacy as
further described below:
The P2P Internet-TV Content Delivery system shall not disclose the user’s credentials (if any) to other
users, externals and operators unless explicitly allowed by the concerned user.
It shall be possible to prevent an eavesdropper from identifying content transmitted over P2P
Internet-TV Content Delivery system through metadata.
The P2P Internet-TV Content Delivery system shall protect the communications between P2P Clients
and between a P2P Client and infrastructure elements against eavesdroppers. This includes both
signalling and content.
Attack wherein a reputation system is subverted by creating a large number of pseudonymous identities in P2P
Attacker-initiated insertion or alteration of passive data in a system which degrades the quality of the service provided
by this system.
Attack whose purpose is to prohibit a legitimate user the use of a service or of a system.
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