audio over ip

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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