VBrick Systems MPEG-4 User manual

VBrick Systems MPEG-4 User manual
VBrick and MPEG-4
It’s not just lower bandwidth
VBrick Systems has a proud history delivering high quality live video over digital
networks to desktops and TV monitors. VBrick invented the Video Network
Appliance back in 1998 and was the first to make live MPEG-1 video reliable and
affordable. VBrick was the first to make live DVD-quality MPEG-2 video available
to desktops for free. And now VBrick is the first to deliver live, standardscompliant MPEG-4 video in a multi-functional, reliable appliance.
This paper sets the stage for VBrick’s MPEG-4 product introduction, and
illustrates the many differences between high bandwidth and low bandwidth
video delivery.
A Bit Of History
The delivery of MPEG-2 requires at least 2 Mbps (MPEG-1 is about half that).
This is a trivial amount of bandwidth for an appropriate network, and from the
White House to Wall Street, there are many thousands of people viewing live
MPEG-1 and MPEG-2 video from VBrick appliances today.
But the “appropriate network” is a dependency, and not everyone can identify
whether his or her network falls into this category. Further, there is high interest
in delivering video to networks that were heretofore, inappropriate. This includes
networks that do not support multicasting, networks that support multicasting but
have pockets of users without multicast support, users connected to a corporate
VPN, and users who only have conventional public Internet access. In other
words, there is interest in sending video to everyone everywhere at any time.
Beyond the above question of “reach” (i.e. the ability of a large audience to see
the video), there is interest in using less bandwidth even when sending a
multicast video. This is true because a multicast video still has to contend for
oversubscribed “uplinks” when it leaves a workgroup.
MPEG-4
It is correct to think of “MPEG-4” as a video compression capability that is a
multi-vendor International Standard. It is correct to think about “MPEG-4” as
producing excellent video quality for a given display size and bandwidth. It is
also correct to think about “MPEG-4” as enabling VBrick appliances to operate at
lower bandwidth.
But it would be wrong to think the story ends there! While MPEG-4 certainly
does these things, VBrick has implemented features and functions that make the
above not only true but also extraordinarily useful, as we will next explore.
VBrick and MPEG-4
Copyright 2003, VBrick Systems
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CONFIDENTIAL, NOT FOR GENERAL DISTRIBUTION --
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1
Multicasting MPEG-4
VBrick is among the world’s leaders in multicasting video. For those familiar with
multicasting via the VBrick 3000 and 6000, MPEG-4 is very similar but uses less
bandwidth to
produce good
MPEG-4 to the desktop via multicast
video.
One need merely
plug a VBrick into
their network,
and every
desktop on that
network may
view the live
MPEG-4 video
using their
StreamPlayer
viewer, or using a
custom web
page.
Corp. Network
Advantages
• Lowest bandwidth usage
• Instant viewing via StreamPlayer
From a user’s
Disadvantages
perspective, they
• Multicast dependent
can view live
• LAN only
• No VPN delivery
MPEG-1, MPEG2 or MPEG-4
video without knowing any more than how to click on a Program Name.
Multicasting MPEG-4 uses up to ten times less bandwidth than MPEG-2 for
applications that call for partial-screen video display1. For small screen display,
the quality is nearly equivalent to MPEG-2. For full screen, MPEG-2 is clearly
superior. This low bandwidth usage encourages extended deployment and
helps to prevent the saturation of router uplinks.
As with any multicast, the network must support IGMP, and it does not work in
older networks or those networks built using inexpensive hubs and switches.
1
Assume MPEG-2 at 3 Mbps and MPEG-4 at 300 Kbps, and assume both are displayed in a
small video window on a PC monitor. The point is, the smaller the viewing window, the less of a
distinction between MPEG-1, MPEG-2 and MPEG-4. For full screen display, MPEG-4 at 300
Kbps might best be called “bad” while MPEG-2 at 3 Mbps might be called “very good”. But both
might be equally regarded as “excellent” when viewed in a very small window. It should be noted
that MPEG-4 at 2 Mbps, even at full screen, might be regarded as “very good” and looks like
normal VHS tape, while MPEG-2 at 4 Mbps would be consistently regarded as “excellent” at all
screen sizes.
VBrick and MPEG-4
Copyright 2003, VBrick Systems
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2
VBrick and RTSP Server
For those familiar with VBrick and multicasting, the new capabilities available
with the VBrick solution requires a fundamental shift in thinking. The Real Time
Streaming Protocol (RTSP) and the integral VBrick Video Server (VVS) conspire
to deliver a new world-class video streaming solution.
In this new model, a desktop client (whether a VBrick StreamPlayer, a Real
Networks player, a Apple Quicktime player, or Microsoft Media Player with the
VBrick plug-in)
makes a direct
MPEG-4 to the desktop via RTSP
request to a VBrick.
The VBrick responds
to the request by
sending MPEG-4
Corp. Network
audio/video directly
to the requester via
unicast. In this
model, every viewer
receives their own
stream and the
network need not
support multicast at
all.
Corporate Virtual
Advantages
Private Networks
• No multicast network dependency
• Supports Corporate VPNs
(VPN’s), for
example, do not
Disadvantages
support multicasting.
• Independent stream for each viewer
With VBrick’s
requires more bandwidth than
MPEG-4 product,
multicast
the VPN user simply
requests the video and the VBrick delivers it to them via unicast UDP.
This capability works in virtually any and all IP networks, including the Internet.
In a local area network, this capability eliminates any dependency on multicast,
but this comes with a price. When every client has their own stream, the VBrick
(and hence the network port it is connected to) can reach very large total
bandwidth numbers. For example, 100 people viewing a 300 Kbps stream would
require (100 x 300,000) 30 Mbps. Were the same 100 people to view via
multicast, only 300 Kbps total bandwidth usage would be required.
VBrick and MPEG-4
Copyright 2003, VBrick Systems
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CONFIDENTIAL, NOT FOR GENERAL DISTRIBUTION --
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3
VBrick and MPEG-4 Webcasting
That VBrick delivers MPEG-4 audio/video at bandwidths from dial-up to DSL &
Cable Modem speeds is certainly noteworthy. The astute observer will note that
there is nothing preventing the video from being viewed over the Internet directly
from a VBrick.
This is indeed the
MPEG-4 Webcasting via RTSP
case.
However, local
network
dependencies
quickly come into
play, both on the
side of the sender
(the VBrick
location) and the
receiver (the
viewer).
INTERNET
Corp. Network
Advantages
• Direct Webcasting to any desktop on the Internet
• Low Cost
For the video to be
viewable on the
Disadvantages
Internet, the VBrick
• UDP blocked by most firewalls, including home routers
server (the VBrick
• For a large number of viewers, requires high bandwidth
itself) must be
connection from the source VBrick to the Internet
(possible high cost)
reachable from the
• VBrick must be outside of the corporate firewall (needs
Internet. This
an “outside” IP address)
means it must be
configured with a unique “outside” IP address, or the local router must conduct
Network Address Translation. This is not at all hard to do, but it does represent
both a dependency and a potential security concern for the network manager.
A deeper concern is that the VBrick delivers its video via UDP, which is exactly
the right thing to do. But many firewalls, both corporate and even home gateway
router devices, may block all UDP traffic making it impossible to view the VBrick
video.
As with any unicasting solution, another issue is the Wide Area Network
bandwidth usage required to support a large number of Internet video viewers. If
the source VBrick is connected to the Internet via a T1 or E1 (typical corporate
access bandwidth), delivering video to just five users at 300 Kbps will consume
the entire capacity (300 Kbps x 5 = 1.5 Mbps).
For viewing by only a few remote workers, or for companies with large WAN
access connections, this may not be an issue.
VBrick and MPEG-4
Copyright 2003, VBrick Systems
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CONFIDENTIAL, NOT FOR GENERAL DISTRIBUTION --
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4
VBrick and MPEG-4 Hosted Webcasting
Webcasting is a powerful tool to deliver a compelling live message to virtually
everyone, anywhere in the world. The nature of live attracts and retains viewers,
and it obviously delivers the same message to everyone at the same time.
Viewers of live webcast streams may be easily given the opportunity to ask
questions or give live feedback via many “Instant Messenger” services, “chat
pages”, or even plan old telephone.
But it may be
unreasonable for an
enterprise to install a
multi-gigabit Internet
access connection to
support hundreds or
thousands of live
viewers, especially if it
is to be used for only
one hour once a week!
MPEG-4 Webcasting via RTSP
REFLECTOR
SERVICE
INTERNET
Corp. Network
Furthermore, there is
interest in delivering the
live webcast from
anywhere at any
time…from your office,
from a boardroom, from
a hotel room, or even
from your home.
Advantages
• Automatic UDP and HTTP
• Streaming through firewalls
• Only one stream sent via Corporate WAN
• VBrick source can be virtually anywhere: Corporate
Headquarters, Branch Office, Home Office, hotel room,
etc.
• Scales to virtually unlimited number of viewers
Disadvantages
• Small, pay-as-you-go bandwidth usage charge
VBrick supports the
unicasting of a stream to an external “Reflector Service”. The Reflector is simply
a high performance server that is connected to the Internet via multi-gigabit
connections.
The VBrick delivers one stream to this Reflector (for example, one 300 Kbps
stream), and the Reflector replicates the stream to any client that requests it.
Importantly, the Reflector is able to negotiate with client viewer. If the client
viewer is unable to view the (preferred) UDP stream, it will deliver the MPEG-4
stream via HTTP (which requires some 30% more bandwidth, but does get
through firewalls).
Because the VBrick sends the video only to the Reflector, the VBrick does not
need an “outside” IP address and can be placed virtually anywhere in any
network that will support the single-stream bandwidth you have configured.
VBrick and MPEG-4
Copyright 2003, VBrick Systems
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CONFIDENTIAL, NOT FOR GENERAL DISTRIBUTION --
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5
Putting It All Together – The Hybrid
We have examined MPEG-4 multicasting, RTSP, and UDP unicasting. But it is
vital to understand that VBrick does all of these things at the same time in the
same appliance!
This is not a “Swiss Army Knife” proposition to solve some unknown problem, nor
is it some unintended artifact. It is a necessary, and revolutionary solution to
very real and very complex problems. Moreover, the simultaneous support for
multiple modes of operation makes the VBrick truly easy to use because it
eliminates so many external dependencies.
MPEG-4 Hybrid Video Everywhere!
REFLECTOR
SERVICE
Web – Unicast / Reflector
VPN - RTSP
Corp. Network
LAN - multicast
INTERNET
VPN
Advantages
• One Appliance, rugged, compact, smaller than a ‘server’
• Simplest Solution
• Best Delivery for the target audience – all at the same time
• Multicast for local area network video
• RSTP / unicast for VPN and some Web viewers
• Unicast to reflector for Webcasting
• Optional MPEG-2 to MPEG-4 live transcoding allows DVDquality in the LAN
Disadvantages
• None
VBrick and MPEG-4
Copyright 2003, VBrick Systems
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CONFIDENTIAL, NOT FOR GENERAL DISTRIBUTION --
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6
Ready…Set…
A single VBrick can truly provide video everywhere by applying the best
technology to the problem at hand:
•
Multicasting the Local Area Network which saves bandwidth
•
Automatic RTSP unicasting in the Local Area Network for locations that do
not support multicasting
•
RTSP unicasting in the corporate VPN to reach remote employees
anywhere in the world
•
Direct webcasting
•
Unicasting to a Reflector service to provide webcasting scale
Plus, the same VBrick also simultaneously supports live MPEG-2 encoding or
decoding. This powerful combination provides:
•
Low bandwidth MPEG-4 for bandwidth-challenged viewers, and DVDquality MPEG-2 video delivered to local desktops via multicast.
•
Live, real-time transcoding of MPEG-2 network video to MPEG-4 video
streams
•
…and the other award-winning VBrick functions and features already
being used around the world for security, education, media distribution,
and more.
Coupled with a VBrick automatically-downloaded-and-installed MPEG-4 decoder
plug-in, StreamPlayer, and other VBrick system elements, virtually unlimited,
standards-based, reliable, live video is a reality.
VBrick and MPEG-4
Copyright 2003, VBrick Systems
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CONFIDENTIAL, NOT FOR GENERAL DISTRIBUTION --
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7
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