Packets Everywhere: How IP-Audio and Ethernet are Transforming Modern Radio Facilities ( 77.03 MB )

Packets Everywhere: How IP-Audio and Ethernet are Transforming Modern Radio Facilities ( 77.03 MB )
Packets Everywhere: How IP-Audio and Ethernet Are
Transforming Modern Radio Facilities
Marty Sacks
Vice President, Axia Audio
Cleveland, Ohio
[email protected]
ABSTRACT
For years, Ethernet has been on the periphery
of radio station infrastructure. We've used it for
traffic management, file sharing, allowing the
Internet into our studios, and some audio playback
— and there's where the story ended.
Now, however, broadcasters are finding interesting new uses for Ethernet, thanks to the emergent audio standard called IP-Audio. IP-Audio
opens up new capabilities and possibilities for
broadcasters because it enables real-time transmission of uncompressed, linear audio alongside direct machine control of audio devices and playout
computers, transmission of PAD / metadata
streams, direct playout of digital PC content sans
audio cards, wide-area connectivity (separate
floors or separate buildings), high-spectrum STL
data links and more — all using the dramatically
reduced wiring infrastructure that the Ethernet environment provides.
This paper will examine some of the innovative
ways radio broadcasters are employing IP-Audio
and Ethernet for applications such as alternative
STL, large-scale studio connectivity, networked
audio monitoring, and remote system administration.
HOW IP-AUDIO WORKS
The mechanics of IP-Audio are fairly well
known, so I’ll give just a brief overview.
To begin, audio sources are connected to “audio nodes” located in studios, server areas or anywhere audio sources exist. The nodes convert analog or AES/EBU signals to uncompressed 48 kHz,
24-bit digital audio, which is then packetized for
transport via Ethernet. Audio streams from the
nodes are assigned unique IP addresses for identification and routing.
After sources are connected, logic ports on audio devices are connected to “GPIO nodes” which
convert start/stop/status commands to packet data
also.
Each node connects to a QoS-compliant
Ethernet switch, which connect to other switches
around the facility, and each node’s audio and control data are “advertised” to the network, for consumption by anyone who needs them. Gigabit
Ethernet or fiber-optic links between switches provide a fat pipe that can handle tens of thousands of
stereo signals per system.
IP-Audio is extremely automation-friendly.
Once audio and machine-control commands are
converted to data, automated software control of
routing paths and switching configurations is not
only possible but desirable, allowing routes or entire networks to be remapped easily using a simple
software interface.
Of course, all this business concerning nodes is
simply the way in which IP-Audio must be implemented today. In the near future, broadcast equipment will have IP-Audio interfaces built in, eliminating the audio/data conversion altogether.
Picture how a built-in IP-Audio interface
would simplify setup of new audio devices. Traditional broadcast phone systems, for instance, typically need wiring for two audio inputs and outputs,
program-on-hold input, logic connections to the
console, a serial control connection for PC screening software — somewhere near 20 separately
soldered connections.
Now picture that same phone system with an
IP-Audio interface. First, you plug an Ethernet
cable into the jack on the hybrid; you plug the
other end into a network switch. That’s it! All that
I/O and logic travel the same cable. Just think of
how much installation time would be saved during
new studio builds!
A side note: IP-Audio technology not only delivers a higher performance / cost ratio (“bang for
the buck”) than traditional methods of studio
building, it saves money outright. Short- and longterm cost benefits can be realized in quite a few
different areas, like materials (cabling and mainframe router/switcher hardware), installation (reduced labor), maintenance and troubleshooting
(simpler infrastructure) and even in time spent
assembling system documentation. Users of IP-
Analog Audio Node
8 stereo inputs, 8 stereo outputs
Analog Audio Node
8 stereo inputs, 8 stereo outputs
Fiber Link
100BT to 100FX
Media Converter (x2)
CAT.5e Cable
CAT.5e Cable
Figure 1
yet, we’ve got to move audio around.
IP-Audio offers a handy alternative to the traditional audio snake. Copper bundles are not so easily scalable! And when you run out of capacity,
you’ve got to pull another. But Ethernet capacity is
easily scalable; a Gigabit or Fiber Ethernet link can
carry multiple hundreds of audio channels at a
time.
In fact, one of the very first installations of IPAudio was for exactly this application, at Clear
Channel’s WREO. They needed a way to move
signals between adjacent buildings, and found that
using IP-Audio nodes in each building, connected
by a fiber link, worked perfectly — and avoided
the cost of having to trench in a conduit for multipair cable.
Figure 1 shows a typical IP-Audio snake, similar to what WREO deployed. IP-Audio nodes
placed in each building are connected to media
converters, and then fiber. Each audio node has 8
inputs and 8 outputs, well under the capacity of a
100 Mbit link, which can transport up to 32 stereo
signals. If more than 8 streams are needed in each
direction, another audio node and an Ethernet
switch are added to each end. More audio nodes
can be added until link capacity is reached. Gigabit
Ethernet can carry up to 250 stereo audio channels.
Of course, building connections aren’t the only
reason for audio snakes. Live performance venues,
worship sound and other staged events are natural
applications. Nor do all IP-Audio snakes have to
be permanent: remote broadcast setups at sporting
venues or other outdoor events can certainly benefit from IP-Audio’s single-cable setup.
Audio networks are finding their installed costs on
new studios or remodels to be between 20% and
35% less traditional hardwired studios.
NOT JUST CONSOLES
When most broadcasters think of IP-Audio,
they tend to relate it to studio replacement. And
why not? With over 500 console / routing systems
on the air at this writing, IP-Audio has certainly
proven itself in this area.
But broadcast engineers are nothing if not innovative. They take new technology and invent
ingenious new ways of using it that even its designers might not have conceived of. And sharp
broadcasters have figured out that once you get
audio into the Ethernet domain, you can do many
different things with it, thanks to IP-Audio’s amazingly easy, flexible, scalable transport system that
can use CAT-5 or CAT-6 cable, fiber or Ethernet
radios – or whatever comes down the pike next –
to economically transport audio and associated
data wherever it’s needed. From the most basic
broadcast plant to the most sophisticated, IP-Audio
can be a great problem solver.
SLIMMER SNAKES
The most basic use for IP-Audio is for constructing audio snakes. Snakes are useful at remotes and at venues of all kinds (including inhouse performance areas) because, like their reptilian namesakes, their relatively slim profiles enable
them to go almost anywhere and squeeze audio
into some pretty tight areas.
In today’s multiple-studio installation, however, the snake is more likely to resemble an Anaconda than the garden variety. Multi-pair cables
comprised of 50, 75 or 100 discrete copper audio
pairs are not only bulky, they’re expensive. And
FLOOR AND BUILDING INTERCONNECT
An IP-Audio application that’s a natural extension of the snake is the interconnection of studios
and technical operation centers in multi-floors or
multi-building facilities. Minnesota Public Radio’s
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to studios
Switches serving•
5th Floor studios
CAT-5e cable
100Base-T
CAT.6 cable
Gigabit Ethernet
Ethernet switch
Central switch
Old Studios
New Studios
Switches serving•
4th Floor studios
Figure 2
the edge switches on both floors of the new studio
complex, as shown in the (much simplified) diagram above.
Now let’s look at the transmitter-to-doghouse
mentioned previously as a solution for solving
lightning isolation problems. Cumulus Media’s
Youngstown, Ohio facility is made up of on-air
and production studios for 6 stations scattered
across two buildings. Also on site are two transmitter buildings containing transmitters for two of
those stations along with the STL and RPU gear
for the rest, all attached to a 700-foot tower. The
distance between the buildings is between 100 and
200 feet, and all are interconnected by copper in a
triangle arrangement. Each building has a separate
power feed as well. Lightning has been a recurring
issue, not to mention simple surge and ground differentials.
The solution was to build a processing / data
rack room and run fiber between that facility and
the other studio and transmitter building, eliminating ground loop problems and helping attenuate
recent studio expansion is a perfect example: their
studios span two floors of a new building, plus two
floors of an adjacent building.
Users have discovered that IP-Audio is a natural for getting audio to and from transmitter shacks
or where satellite or RPU receivers are located.
Some have told me that fiber is an excellent connection method for this application, because it
greatly reduces the potential for transmitted lightning damage — fiber doesn’t conduct!
Let’s look at the Minnesota Public Radio example first. MPR put a central switch in their new
building, a load-balancing bladeserver from Cisco.
The old studios that needed connection with the
new ones are located in an adjacent building with a
shared wall, so a Gigabit Ethernet link was run
from the central switch through the wall to an edge
switch that served the audio nodes in the old studios. These nodes use CAT-5e to connect to their
edge switch, which connects to the central switch
in turn with CAT-6 (for Gigabit).
The central switch also connects via Gigabit to
Transmission Lines
Studio Switches
and Audio Nodes
CAT.5e Cable
100Base-T
Satellite &
RPU Receivers
Transmitter building switches & Audio Nodes
(program feeds and xmtr control)
Fiber Links
LAN
Central Switch
Studio Buildings
Doghouse Switch
& Audio Node
Figure 3
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Systems, Google/dMarc, iMediaTouch, Netia,
Pristine Systems and Prophet Systems, to name a
few. Media giants such as Univision, Clear Channel and France’s Lagardere Group have already
built facilities using this tight PC/router model.
Of course, this approach isn’t mandated. IPAudio systems coexist quite nicely with traditional
sound cards (by simply plugging their inputs and
outputs into Audio Nodes).
Even sound card providers themselves realize
the benefits of IP-Audio compatibility. Respected
audio-card maker AudioScience recently announced their intention to manufacture a broadcast-quality card that works directly with IP-Audio
networks. Instead of the usual “pigtail” and tangle
of I/O and logic connectors, multiple channels of
audio and control data will travel from the card
directly to the network over a single thin Ethernet
cable.
lightning attraction, as well as breaking the conductive link between buildings.
A combination of bidirectional AES, analog,
and Ethernet has to be carried over this fiber, and
Cumulus engineers found, after extensive research
of fiber-only systems, that Ethernet combined with
fiber provided more flexibility.
As shown in Figure 3, IP-Audio nodes and
Ethernet switches equipped with GBIC (Gigabit
Interface Converters) are placed in each location.
Connecting all of the switches with fiber creates an
IP-Audio network across all of the buildings, allowing sharing and routing of audio, device control
and LAN traffic, eliminating ground loop problems and effectively limiting potential lightning
damage to very localized areas.
SOUND CARD ALTERNATIVES
The phrase “paradigm shift” is overused, so I
apologize in advance for using it here! Overuse
aside, however, it’s an accurate description for an
IP-Audio application that has the potential to completely revolutionize one segment of broadcast
studio architecture.
Since IP-Audio converts audio and control into
routable Ethernet data, and since Ethernet was designed to facilitate computer users’ exchange of
PC data, it stands to reason that PC audio workstations should be able to exchange audio with the
rest of the network directly, right? And they can.
PC audio workstations or audio delivery systems
can be equipped with an IP-Audio Driver that
emulates a soundcard. The driver can then route
multiple channels of audio playback, record and
data/logic command streams via the PC’s Network
Interface Card (NIC), which connects with the
local Ethernet switch.
Many IP-Audio users have discovered that they
can save substantial amounts of money by using
this approach. Not only is there money saved on
sound card purchases, but also on associated wiring. Not only that, the cost of the router switcher
port (or console input module) that a traditional
hardwired router system would require for these
sound card inputs is eliminated as well. Once PC
audio sources are part of the Ethernet data flow,
they are universally available as IP streams and
can be switched or mixed as needed.
Users have been quick to realize the benefits of
this approach, and many well-known delivery system providers have announced that they have IPAudio drivers available for popular playout systems. These providers include the likes of Broadcast Electronics, BSI, D.A.V.I.D. Systems, ENCO
ROUTING SWITCHERS, REMIXED
While the routing switcher is a pretty familiar
sight, especially in larger markets, IP-Audio users
have found some new ways to build them.
Traditional routers are usually fairly large and
complicated, with topologies of 64x64 crosspoints
or larger. IP-Audio users have found that, thanks to
Ethernet’s inherent scalability, it’s not only possible but practical to assemble an audio routing
switcher as small as 8x8 stereo inputs and outputs
(analog and/or digital, with or without program
associated data) that could scale to a very large
system without huge jumps of costs or complexity.
Conventional routing systems, while serving
their purpose well, nonetheless force a choice during initial planning and building: the “small frame”
and the “big frame.” And this choice must be made
before even one cable is run. Studio projects are
constantly in flux during construction, and requirements often change mid-stream. The result: if
you purchase more capacity than you thought
you’d need, money is wasted. If you purchase too
little capacity, costs escalate rapidly when it comes
time to correct that mistake: most routing switcher
frames are custom-built, so if you wind up with
more inputs than your router frame is capable of
taking, the only solution is a second, expensive
frame.
Another consideration is the cost of the multiple plug-in I/O cards that hardwired routers require. And it‘s not like you can re-use them: cards
from one system – even from the same manufacturer – often cannot be used in a different card
cage.
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which have 8 stereo inputs and 8 stereo outputs. The nodes are connected
to a 100/1000Base-T Ethernet switch
using inexpensive CAT-5e cable. Only
Analog Audio Node
8 stereo inputs, 8 stereo outputs
one Ethernet cable is needed to connect each node to the switch, because
each 100Base-T link has enough capacity to carry 32 stereo signals — all
running at once! Automated routing
control and scene changes can be hanPathfinderPC •
Ethernet Switch
dled by software running on a conRouting Software
nected PC.
32x32 is a pretty respectable rout32x32 Routing Switcher
ing
system, easily capable of serving
Analog Audio Node
8 stereo inputs, 8 stereo outputs
two or three studios, but times change
and needs grow. IP-Audio users have
found that it’s especially easy to add
AES/EBU Audio Node
8 stereo inputs, 8 stereo outputs
capacity to their routing systems beFigure 4
cause all they have to do is connect more nodes to
the existing setup, again using standard CAT-5e.
IP-Audio could completely change the way
As you can see in Figure 5, the original 32x32
routing applications are constructed. Thanks to the
system is still intact — but with more Audio nodes
scalability of their Ethernet backbone, small sysadded to accommodate increased routing demand,
tems can be built with relatively little initial cash
doubling the size of the original routing switcher
outlay. Then, when more capacity is required, the
system to 66x66.
network can be expanded, again and again if need
Should the need for more capacity arise, the
be, without ever discarding the original parts of the
same procedure is repeated, adding more nodes
system. An IP-Audio router can thus grow from
where they’re needed. Figure 6 shows how the
very small to very large at a very predictable and
original system has expanded yet again to a
linear cost.
132x132 router.
Figure 4 underscores this point, demonstrating
As it’s somewhat related, this is a good place to
how, with very little equipment, you can easily
mention another neat benefit of IP-Audio systems:
construct a 32x32 routing switcher using IP-Audio
portability.
components.
With traditional router systems, it’s nearly imThe diagram shows four Audio Nodes, each of
possible to re-use hardware in a new location. A
Analog Audio Node
8 stereo inputs, 8 stereo outputs
Router Selector Node
1 stereo input, 1 stereo output
Analog Audio Node
8 stereo inputs, 8 stereo outputs
Analog Audio Node
8 stereo inputs, 8 stereo outputs
Analog Audio Node
8 stereo inputs, 8 stereo outputs
Analog Audio Node
8 stereo inputs, 8 stereo outputs
PathfinderPC •
Routing Software
Ethernet Switch
66x66 Routing Switcher
Router Selector Node
1 stereo input, 1 stereo output
Analog Audio Node
8 stereo inputs, 8 stereo outputs
Analog Audio Node
8 stereo inputs, 8 stereo outputs
AES/EBU Audio Node
8 stereo inputs, 8 stereo outputs
AES/EBU Audio Node
8 stereo inputs, 8 stereo outputs
Figure 5
-5-
Analog Audio Node
8 inputs, 8 outputs
Analog Audio Node
8 inputs, 8 outputs
Analog Audio Node
8 inputs, 8 outputs
Analog Audio Node
8 inputs, 8 outputs
Analog Audio Node
8 inputs, 8 outputs
Router Selector Node
1 stereo input, 1 stereo output
Analog Audio Node
8 stereo inputs, 8 stereo outputs
Analog Audio Node
8 stereo inputs, 8 stereo outputs
Analog Audio Node
8 stereo inputs, 8 stereo outputs
Analog Audio Node
8 stereo inputs, 8 stereo outputs
PathfinderPC •
Routing Software
Ethernet Switch
Router Selector Node
1 stereo input, 1 stereo output
132x132 Routing Switcher
Analog Audio Node
8 stereo inputs, 8 stereo outputs
Analog Audio Node
8 stereo inputs, 8 stereo outputs
AES/EBU Audio Node
8 stereo inputs, 8 stereo outputs
AES/EBU Audio Node
8 stereo inputs, 8 stereo outputs
Analog Audio Node
8 inputs, 8 outputs
Router Selector Node
1 input, 1 output
AES/EBU Audio Node
8 inputs, 8 outputs
AES/EBU Audio Node
8 inputs, 8 outputs
Router Selector Node
1 input, 1 output
Figure 6
These combinations of IP-Audio gear and
Ethernet radios can provide multiple channels of
bi-directional analog or AES audio (as well as
GPIO commands for remote control of transmitter
rack equipment such as audio processors satellite
receivers). And, unlike traditional STL, these audio channels are uncompressed, so transmissionrelated coding artifacts are eliminated.
(A side benefit to this transmission method is
that the link can be easily reconfigured to add and
subtract audio channels — an excellent fit for HD
Radio applications with multiple concurrent program channels.)
An example of such an installation using
Ethernet radios is found in use at the cluster of
radio stations operated by Clear Channel in Birmingham, Alabama.
Chief Engineer Bob Newberry found that the
portion of the local spectrum he’d used for years
for STL was unsuitable for future HD Radio implementation. Also, his stations had actually been
taken off the air due to interference when another
station accidentally fired up transmissions on the
same frequency.
Eyes to the future, Bob considered IP-Audio as
a way to solve not only frequency crowding, but
also to consolidate multiple audio and data channels into a single transmission path.
different building means different card cages, different locations for inputs and outputs — not to
mention all the expensive multi-pair cable that is
thrown away.
In sharp contrast, IP-Audio routing systems can
literally be picked up and moved to a new location.
Since audio nodes are rackmount devices, they can
simply be racked in the new facilities and connected with Ethernet. A little bit of software reconfiguration, and the entire system is online again.
UNCOMPRESSED STL
Everybody knows that the 950 MHz STL band
is terribly crowded in all but the smallest markets.
Hardly a month goes by where there isn’t a story
about a market where somebody was knocked off
the air by another station turning on an STL, or
where STL bandwidth is reduced by the frequency
coordinator.
An innovative use of IP-Audio is helping to
solve these problems in several markets. Broadcasters are using IP-audio nodes, combined with
Ethernet radios from providers such as Broadcast
Electronics, Dragonwave and Orthogon to replace
950 MHz transmissions with license-free data
channels in higher-frequency bands.
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Figure 7
sites.
Fortunately, the ISP was able to offer a guaranteed bandwidth service to the two sites at a cost
much lower than the alternatives. To avoid paying
Telco costs, Latnet installed a 26GHz IP radio link
with equipment made by Netro to Radio Skonto’s
studios. Radio Skonto contracted for 384kbps from
the Riga studio and 256kbps at each of the remote
sites, providing plenty of margin for packet overhead.
Radio Skonto decided to use Telos Zephyrs to
provide MPEG compression and IP conversion.
The station is a fully IP-Audio networked facility,
so they wanted to input audio to the Zephyr at the
main site via IP. This was accomplished by simply
plugging it in to a spare port on the Ethernet switch
and configuring the main IP-Audio program channel as its input source. A low-cost ($50) consumer
IP router was used to connect the Latnet IP radio to
another port on the Ethernet switch. This router
was “locked-down” to pass only the required audio
signals, and thus to isolate the IP-Audio network
from any other traffic on the external network. The
Zephyr provides two streams, one for each site.
At each remote site is a small studio set-up for
local programming. The Zephyrs deliver their audio outputs via analog connections to a console
fader input; DSL lines provide the IP connection.
As before, these are firewalled with a low-cost
router inserted between the DSL line and the
Zephyr; see Figure 8 for a simplified diagram. The
routers have additional LAN ports that are connected to some other PCs used for non-real-time
audio transfer;
The station was naturally concerned about delay, wanting the lowest possible value so that people listening to live telephone calls would not be
The Birmingham cluster was already feeding
four transmitter sites with two 4-channel STL systems, and employed a LAN extender to get RDS
data and transmitter remote control to the transmitter site. With three HD-2 channels planned for
broadcast, the question arose: how would they get
the additional audio (plus associated RDS and remote control) to the transmitter site without overloading the existing gear?
Investigation showed that an Ethernet radio
with a 100 MB/s bidirectional link would have
enough capacity for audio, PAD and control data,
plus room for more audio/data channels should
future plans so necessitate.
To implement the system, audio nodes were
placed on either end of an 18 GHz link; the simplified diagram shown in Figure 7 illustrates how
program content, audio backhaul and even streaming images from security cameras coexist on the
same “STL” link.
At the time of this writing, the system will be
celebrating its first anniversary in service; performance has been flawless.
A second example comes from Radio Skonto
in Riga, Latvia. They’d received a license for
transmitters in two other cities outside their main
service area, and management was quite pleased.
But for engineer Ivo Bankovs, the problem was
one of distance: how would he get the signal from
the studio in Riga to the cities of Rezekne and
Liepaja, each about 250km away?
Traditional Telco audio service was very expensive. Installing his own STL radio system was
impractical due to the need for intermediate repeaters and towers — if he could get a license. So
he asked a local Internet Service Provider, Latnet,
if it would be possible to use IP links to the two
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Remote Studio 1
Zephyr With IP In/Out
Zephyr With IP In & Analog Out
To Local Studio
Analog Console
IP Router
IP Router
Remote Studio 2
Zephyr With IP In & Analog Out
To Local Studio
Analog Console
Ethernet Switch
IP Router
Figure 8
TOC rack with distribution amplifiers, tuners, line
selectors and other gear… and then running more
cable to individual offices throughout the facility,
outfitting them with speakers, volume controls, et
cetera.
Needless to say, this can be an expensive and
time-consuming endeavor. As a result, these projects end up being very costly or providing less
monitoring points than desired.
IP-Audio users have found that they can use
PCs connected to their audio network to provide
monitoring for practically everyone in a networked
facility by using software applications that translate networked audio streams to PC audio playable
on any local computer.
In this way, anyone connected to that network
can monitor air – or any other available audio
stream – using the speakers already attached to
their computer. GMs, Program Directors, salespeople and programming staff can all listen to their
choice of air monitors instantly, from any location,
with no additional equipment to purchase and install or extra cable to run.
Quite a change from the old Altec corner
speaker hung in the GM’s office.
confused (the station runs without a profanity delay). To accomplish this, they set their Zephyrs to
the lowest buffer setting: 250ms. They were not
sure if a setting that low would work, but decided
that the best strategy would be to start with a
minimum value and increase it in small steps until
any audio drop-outs stopped.
As it turned out, the minimum setting worked
without problem — fortunately, the IP network
had very low jitter.
Ivo and his assistant engineer, Karlis Malkavs,
wondered if 128kbps would provide sufficient
quality and were ready to increase to a higher rate
if compression artifacts were evident. But after a
month of on-air operation, they decided to stay
with this lower rate. MPEG AAC has been officially designated as “indistinguishable from the
source” at 128kbps by the European Broadcasting
Union; this real-world application certainly proved
it to be so!
The system has been in operation for a number
of months and is working well.
There was an outage at one of the sites caused
by a power failure affecting the ISP’s equipment
center. A UPS was supposed to provide back-up,
but a switch in the path was mistakenly not connected to the UPS. Other than that, Ivo reports no
problems. The ISP’s promise of guaranteed bandwidth has been kept, and the IP option has proven
to be a satisfactory studio-to-transmitter link.
FACILITY AUTOMATION MATURES
The more activities (routine and emergency)
we can simplify or take out of the hands of operators, the more reliable our plants are likely to be.
IP-Audio, thanks to its computer-tech base and
subsequent natural capability for integrating and
interacting with PCs, is working changes in this
area as well.
Certainly, we’ve had some ability to automate
aspects of the broadcast environment before: audio
AUDIO MONITORING FOR ALL
Listening stations are another area being
transformed by IP-Audio. Until very recently,
making listening stations available for GMs, PDs,
Sales Directors – even the DOE! – meant filling a
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gram feed origination to another studio) switching
functions with just one tap.
An informal poll reveals that roughly 90% of
broadcasters who adopt IP-Audio studio architecture opt to include this sort of advanced automated
control; such systems are in use at stations belonging to Univision, Clear Channel, Cumulus Media,
MPR and many others.
processors with dayparting capabilities are a good
example; PC-based audio delivery systems are
now so ubiquitous that the service they provide
(with smoothness and accuracy unthought-of in the
Schaeffer days) is routinely taken for granted.
But now, with computers tied even more
closely to hardware, software applications can take
control of nearly every audio device throughout
the plant. They can administer pre-scheduled routing scene changes, react in predetermined ways to
trigger events, even take emergency action in the
absence of station personnel.
PathfinderPC is such an application. It can
work with several different kinds of routing
switchers, and is optimized for control of IP-Audio
networks. Pathfinder contains powerful scripting
capabilities that use simple and familiar Boolean
logic to enable users to construct logic trees, building applications that react either to direct user interaction such as a button press or contact closure
activation, or to pre-defined fault states such as
dead air, loss of program feed or diminished audio
levels. Scheduled routing changes can also be programmed.
INTERESTING CONSOLE APPLICATIONS
There are some unique benefits associated
with IP-Audio mixing consoles that can help simplify life in the studio. First, a console in an IPAudio system makes the distribution of I/O, logic
and backfeeds easier than ever.
Sharing a standard audio connection in a traditional studio means two pairs for the stereo audio,
another two pairs (at least) for machine control
logic, and another two pairs for a backfeed or mixminus. That’s at least 6 pairs of wire for each audio connection, multiplied by the number of places
you need to send it.
By contrast, an IP-Audio studio setup reduces
the amount of wiring needed by an order of magnitude, because audio I/O, machine logic and even
mix-minuses are all converted to digital streams,
which are routed together in a single “bundle” of
packets using Ethernet cable which can be shared
with hundreds of other like signals. But elimination of wiring isn’t the best part — there’s also the
fact that since audio, logic and backfeed are now
part of the same digital package, you will always
receive the correct mix-minus when routing remote
or telephone audio. In other words, you can bring
up a codec or hybrid on any console and it always
works right.
Speaking of phones, IP-Audio also provides
much tighter phone/console interoperability than
has ever been possible before. With traditional
consoles, phone operations have required outboard
controllers – switch panels or phone-like devices –
to control the hybrid. This interrupts the workflow
in the control room, since the jock has to take his
hands and eyes off the console to work another
device. Drop-in control panels for consoles mitigate this somewhat, but these controls are often not
adjacent to the audio faders themselves, and in any
case require discrete wiring for audio, hybrid control and mix-minuses.
As noted previously, IP-Audio networks route
I/O, control and backfeeds together, so the phone
controller can live in the console, right next to the
audio faders, and the console can receive audio,
generate hybrid control logic and send mix-minus,
Of all the ways in the world to be awakened, a
phone call at 3AM is one of the least enjoyable.
Pathfinder can help take the urgency out of unexpected events by sensing and reacting to loss of
program audio.
Let’s say that (at 3AM, of course) a satellite
channel supplying programming suddenly goes
dark. Pathfinder’s silence-sense function can be
programmed ahead of time to deal with such a
problem; when audio drops, it takes an alternate air
feed. There’s e-mail notification capability too –
conditional routing scenes can be defined so that
if, for instance, a primary ISDN feed gets knocked
out, the system switches to backup and sends an email to your Blackberry® telling you what happened.
Another aspect of PathfinderPC is its support
for touch screen monitors. On-screen “virtual button panels” can be constructed to run on local PCs
so that board ops can execute simple (changing
satellite receivers) or complex (transferring pro-9-
IP telephone. And the adoption by consumers of
mass-market VoIP services over broadband Internet access which began in 2004 continues unabated. According to research firm Cahners InStat, more than 9 million US households now have
at least one active VoIP user; it was estimated at
the end of Q4 2006 that nearly 8% of U.S. households now use a VoIP telephone service —up from
6.5% just six months prior.1
Finally, the television industry has embraced
Video-over-IP with a fervor. Gone are the days of
sending dubbed U-Matic cartridges to other stations by courier, or even satellite uplinks: TV production facilities now share content via video
gateways that link production facilities and television stations with each other directly via IP connection. Writing in Broadcast Engineering, Brad
Gilmer asserts that “Video over IP is destined to
become the predominant technology for the transport of professional video over WANs.”2 And, as
with IP telephony, this service is spilling over into
the consumer arena with IPTV reaching millions
of homes via digital cable services.
With this data in mind, it’s certainly no stretch
to predict that IP-Audio is on a course to revolutionize the broadcasting industry. More and more
applications for this technology are being discovered as the numbers of IP-Audio installations rise.
The question for radio broadcasters is not whether
to transition to IP-Audio, but when.
all over the same Ethernet cable. Another benefit is
that the hybrid itself doesn’t need to be located in
the studio anymore — it can be placed in the TOC
or some other central rack room, safe from curious
hands.
Finally, something I consider to be a very
unique console application: the ability for two consoles to work simultaneously with shared sources.
Imagine a scenario in which talent in the talk
studio wants their own level control of some audio
devices. But the control room operator needs to
keep control of the levels in order to “assist” the
talent should they run their audio at the wrong
level.
The solution: link motorized faders on the
control room and talent consoles, designating the
CR as the “master” console, and the studio as the
“slave.” This allows talent to set levels as desired,
but also allow the board op to override those levels
as needed – something that can’t be done with a
traditional console setup.
CONCLUSION
Historically, IP-based systems have worked a
sea change in every industry into which they have
been introduced.
The World Wide Web would not exist if not
for IP. Defense computers connected with serial
data transmissions formed rudimentary networks
in the 1960s, and those networks expanded with
ARPANET in the 1970s. But the development and
implementation of TCP/IP on ARPANET in 1983
led directly to the growth of what is now the Internet.
Banking networks using ATM (Asynchronous
Transfer Mode) revolutionized that industry in the
1970s by allowing computers to take on the tedious accountancy handwork that was the foundation
of banking. But the implementation of TCP/IP
over ATM made possible instant money transfers
between far-flung locations. Remember the days of
hurrying to the bank on Fridays (between 10 and 4,
of course) to get cash for the weekend? Now, instant banking and automated tellers are available
24/7 thanks to IP.
Telephone systems have undergone tremendous change thanks to IP. Traditional PBX systems
and Centrex lines considered advanced only a few
short years ago are now being abandoned in favor
of VoIP (Voice over Internet Protocol) systems
that are more flexible and more cost effective than
the old services could ever be. The migration to
VoIP has been so universal that in early 2006,
Cisco announced that it had sold its 7.5 millionth
1
“Report Sees Rise in Residential VoIP Service”, Cabling Installation & Maintenance Online, December 22,
2006 (http://tinyurl.com/3cmvcw)
2
“Video Over IP”, Broadcast Engineering, August 1,
2006 (http://tinyurl.com/23mwky)
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