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A simple presentation of Audio over IP in which communications
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IntroductionIn Radio broadcasting setup audio mixing
console is the heart of the system and remained relatively unchanged for more than twenty years.
The broadcast studios of today rely on expensive and proprietary communication means in order to network the large number of studio devices.
Originally, source equipment connected to stand-alone mixing consoles with discrete analog signals.
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IntroductionLater, the preferred method of
interconnection became AES/EBU digital. Using modern computer networking
equipment, it is now possible to build robust Networks capable of transporting digital media signals throughout a complete studio facility.
Introducing an IP-based network in the studio environment is becoming an increasingly attractive solution.3
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Sources are different now
Days have gone of playing from carts, vinyl, cassette and reel tape in a typical broadcast.
Most program audio is now recorded, edited and played out of a PC system.
While consoles remain much the same, the PC has quietly taken center stage in today’s radio studio.
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Sources are different now
Traditional consoles handle PC audio the same as any discrete source, hindering potential intercommunication that might enhance accuracy and efficiency.
Instead of using analog or AES/EBU audio as the interconnection standard, it is believed that all broadcast audio systems of the future will use networked Ethernet to provide a much more flexible and cost-effective alternative to console systems used today.6
Why Ethernet
Ethernet is so much better.
•Very active development.•500+ channels (on Gigabit link).•Bi-directional traffic.•Easy RJ-45 connectors.•All the data capability we need.•Ubiquitous computer standard.•Routing, networking: inherent (low cost).
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Today’s Ethernet…100 Mbps to 1 Gbit.CAT 5e/6 Copper or Optical Fiber.Switched star, not shared – No
collisions.Full-duplex.Priority for audio Quality-of-Service.Multicast allows one-to-many.
… is not your grandfather’s Ethernet!9
Enormous Capacity
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Ethernet is commonplace
Radio facilities are fully networked. Almost.11
IP-based audio systems represent the future.
IP Audio SystemsToday, IP-Audio is making traditional audio distribution infrastructure as obsolete as the cart machine.
These systems use the same IP technology that powers business data networks.
IP-Audio eliminates the discrete-wiring model used since the dawn of radio.
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What is IP-Audio RoutingIt’s not Internet audio!Uses switched Ethernet48 kHz / 24-bit uncompressed audioDelivers real-time audio with guaranteed QoS
Routes machine logic, PAD, custom backfeedsalong with audio sourceElement
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IP Audio networks enable broadcasters to cut costs by using a common transport mechanism for audio, control, messaging, and other data traffic such as files and e-mail and VoIP phones.
Why are IP-Audio Networks
considered to be the future of the broadcast
plant?
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IP-Audio networks provide broadcasters the flexibility to grow and change at will. Traditional systems lack this flexible connectivity.
Why are IP-Audio Networks
considered to be the future of the broadcast
plant?
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IP-Audio Defined
What is IP-Audio?Digital audio over EthernetDesigned to replace bulky cablesProvides converged audio and data pathsEnables source sharing between multiple studios, stages or locations
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IP-Audio, Like VoIP?“Isn’t that like VoIP?”IP-Audio Differences:
High bit-rate, full fidelityIsochronous and multi-channelHigh-reliability
Guaranteed QoSLow latencyNo packet loss
Linear, uncompressed audio18
Why not AES/EBU?
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•Dead end: No development for 15 years.
•One channel, one way.•Soldered XLR connectors.•No significant data capability.•Low volume, expensive.•Routing requires complex hardware.
Standard Ethernet Protocols
QoS (Quality of Service)STP (Spanning Tree Protocol)IGMP (Internet Group
Management Protocol)UDP (User Datagram Protocol)
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THE FUTURE IS NOWThe broadcasting industry is on the verge of an IP-fueled revolution in
distribution and infrastructure design
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How Audio RoutedLow cost mass market Ethernet switches offer this
function.Since their function is to direct packets from port
to port, we can use them to move our signals from whatever source to whatever destination we want.
Simple, flexible, facility-wide audio routing system, almost for free.
Goodbye to racks of distribution amps or expensive proprietary main frame router.
An audio source entered into the system from any point becomes available for any number of receiving destination.
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• Soundcard emulation driver directly packs / unpacks audio to / from system Ethernet.• No hardware needed.• Balanced I/O with more than 100dB dynamic range, < 0.005% distortion, headroom to +24dBu, etc.• It make excellent multi-channel “soundcards” for professional applications.
High-Performance Sound Card Replacement
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High-Performance Sound Card Replacement
• Sound card problems such as noise and multiple conversions are avoided-audio remains in digital form from the PC’s files to the network with no alteration or degradation.
• With so much audio in radio stations being either played from computers or recorded into computers, it is a tremendous advantage.
• Thus lowering cost and eliminating conversion steps.
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FidelityInternet streams are usually compressed for
transmission over public links with limited, variable bandwidth and low reliability.
But in Broadcast Ethernet Networked studio, audio is not compressed- it uses studio grade 48khz/24-bit-PCM encoding.
Dynamic range more than 100dB, <.005% THD, and headroom to +24dbu.
LANs offer a safe, controlled environment, no risk of audio drop-outs from network problems and plenty of bandwidth for many channels of high-quality audio without compression.
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ConvergenceIP is growing as a universal transport for
almost any kind of signal.It is now in television studios, business
teleconferencing, government communications, banking, etc.
PBX companies like Lucent, Nortel, Mitel, Alcatel, and Siemens have plunged into IP transport for their telephone products.
An Ethernet network being used for audio in broadcast studio may be shared with any other data like computer data, telephone, audio, and control on a single network and this will use computer/telephone industry standard wiring. 26
How IP-Audio works:
An Ethernet switch becomes an audio router.
Advertises audio sources to receivers.
All sources available everywhere.27
How IP-Audio works:
Audio sources connect to “audio nodes”
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How IP-Audio works:
Nodes convert audio to uncompressed, 24-bit/48 kHz
digital audio, then translate it to packet data29
How IP-Audio works:
Each audio node input/output is assigned an IP address for
identification and routing purposes30
How IP-Audio works:
Logic ports on each device are connected to GPIO nodes, which convert on/off, tally and other
commands to packet data31
Nodes in Studios
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How IP-Audio works:
Each audio source is given a channel number. Each node is
assigned an IP address for identification and routing purposes
To LAN
192.168.2.30
301 302 303
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How IP-Audio works:
Each node makes its audio and control data available to the
network34
How IP-Audio works:
Each studio’s local Ethernet switch is connected to the other rooms via
core switches or daisy-chain
Studio A Studio B Studio C
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How IP-Audio works:
Complete Studio36
Network Multiple Studios.
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HOW IP-AUDIO WORKS
Compared to traditional multi-line broadcast phone systems, an IP-Audio based system requires only a single Ethernet connection – simplifying installation
By integrating IP-Audio interfaces into equipment,
installations are greatly simplified
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HOW IP-AUDIO WORKS
With an IP-Audio based computer delivery system, audio travels to the network via the computer’s NIC card – without soundcards, multiple audio lines, or D/A/D conversion
By integrating IP-Audio interfaces into equipment,
installations are greatly simplified
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HOW IP-AUDIO WORKSBE, BSI, D.A.V.I.D. Systems, dMarc,
Enco, IDC, Netia, Omnia, OMT, Pristine Systems, Prophet Systems,
Radio Systems, Synadyne, Telos and Zenon Media have all announced IP-
Audio system compatibility
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HOW IP-AUDIO WORKS
In addition to simplified installation, lower costs – both
short and long term – are significant benefits of IP-Audio
systems
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Audio over Ethernet/IP:Why Is It So Good?
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• Supported by huge R&D from the computer and telephone worlds.
• Common, universal wiring.• As with PCs, volume brings
performance, variety, and low-cost.• Learn one system, then you
understand audio, phones, and data.• AIR has already invested in huge
infrastructure of CAT 6 networked modern PC network at all stations.
Audio over Ethernet/IP needs:
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• 100% Reliability.• Low Delay.• One-to-many Routing.• Source Advertising.
Reliability
• Each node “owns” entire link.
• Full Duplex.• Switched.• Cannot exceed link capacity.
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Modern Ethernet’s Priority System.
Lets you combine audio, control, and data traffic on the same network, with no audio dropouts.
Input
Port
Output Section per Port
High-priority Queue
Low-priority Queue
InputPort
OutputPort
Classify
Classify
Mux
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Delay- LatencyIn broadcast studio, we are very much
concerned about the audio delay in the microphone-to-headphone path for live announcers.
Packetizing audio for network transmission causes delay.
Internet audio delay is often multiple seconds because the receiving PCs need long buffers to ride out network problems and the delays inherent in multiple-hop router paths.
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Delay- LatencyDelay Effect
1-3 ms Undetectable
3-10 ms Audible shift in voice character
comb filter effect
10-30 ms A slight echo turning to obvious slap at 25-30ms
30-50 ms Disturbing echo, disorienting the announcer
> 50 ms Too much delay for live monitoring
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With fast Ethernet switching on alocal network, it is possible to achieve
very low delay.
Delay Problem being solved
Short packet length.Short packets require less buffer time.
Low jitter = small buffers.Low jitter means timely packet delivery.Timely delivery means no buffering
required.
To achieve low jitter, every node has a sophisticated sync method using an extremely precise PLL.
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APPLICATIONS:Interchangeable StudiosFor years, broadcasters have built “Mirror”
studios for interchangeable use, but…Taking any room to air as needed presents
logistical challenges with traditional hardwired systems.
With its decentralized, shared data approach, IP-Audio networks simplify construction and use of identical studios
Gigabit Ethernet has the capacity to carry hundreds of simultaneous stereo audio channels per link – with audio, logic, and program associated data all traveling the same CAT-6 cable50
APPLICATIONS:Simple ScalabilityHardwired facilities are not amenable
to growthIP-Audio networks are not subject to the
growth limitations of hardwired systemsAdding a new studio to the network is
accomplished by connecting its audio nodes to a local Ethernet switch, which links to the core switch via CAT-6; then assigning IP addresses to the new inputs
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APPLICATIONS:Quick Changes
With router/switchers, making system changes or additions can prove difficult
• Routers is limited in terms of capacity
• IP-Audio networks solve this problem because they are both scalable and modular
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APPLICATIONS:Progressive Buildouts
IP-Audio network’s ability to not only scale, but to co-exist with other
systems enables broadcasters to begin migrating to new technology
without being forced to make wholesale changes to existing
studios
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Each bidirectional Gigabit Ethernet link can transport up
to 200 channels simultaneously – eliminating multi-pair, home-and-back
cable runs, punch blocks, and soldering - along with most
infrastructure troubleshooting
APPLICATIONS:Painless
Configuration/Documentation
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Since all parts of an IP-Audio network have assigned IP addresses, the ability to remotely administer the
system is built in
APPLICATIONS:Remote Administration and
Control
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Benefits – IP AudioSimplified and unified cablingNo multiple conversions.Integrated data means you are ready for
synchronized text and metadata.Tighter integration with delivery systems
means that mixing, scheduling, and playing can work together.
Low-cost power.Surround-ready.Provisions for Redundancy.Resource sharing is so easy.Codec, Audio Processors, STL , EPABX,
CCTV, all are coming as IP enabled. For their efficient use, it is most essential to timely changeover technology for studios too.56
CONCLUSIONThe numerous operational
benefits of IP-Audio networking have been and are being continuously proven by
professional broadcasters around the world each and
every day.
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