audio Audio most commonly refers to sound, as it is transmitted in signal form. It may also refer to: Sound *Audio signal, an electrical representation of sound *Audio frequency, a frequency in the audio spectrum *Digital audio, representation of sound ...

and

broadcast Broadcasting is the data distribution, distribution of sound, audio audiovisual content to dispersed audiences via a electronic medium (communication), mass communications medium, typically one using the electromagnetic spectrum (radio waves), ...

engineering, Audio networking is the use of a

network Network, networking and networked may refer to: Science and technology * Network theory, the study of graphs as a representation of relations between discrete objects * Network science, an academic field that studies complex networks Mathematics ...

to distribute real-time

digital audio Digital audio is a representation of sound recorded in, or converted into, digital signal (signal processing), digital form. In digital audio, the sound wave of the audio signal is typically encoded as numerical sampling (signal processing), ...

. Audio Networking replaces bulky snake cables or audio-specific installed low-voltage wiring with standard network

structured cabling In telecommunications, structured cabling is building or campus cabling infrastructure that consists of a number of standardized smaller elements (hence structured) called subsystems. Structured cabling components include twisted pair and opt ...

in a facility. Audio Networking provides a reliable backbone for any audio application, such as for large-scale

sound reinforcement A sound reinforcement system is the combination of microphones, signal processors, amplifiers, and loudspeakers in enclosures all controlled by a mixing console that makes live or pre-recorded sounds louder and may also distribute those sou ...

in stadiums, airports and convention centers, multiple

studio A studio is a space set aside for creative work of any kind, including art, dance, music and theater. The word ''studio'' is derived from the , from , from ''studere'', meaning to study or zeal. Types Art The studio of any artist, esp ...

s or

stage Stage, stages, or staging may refer to: Arts and media Acting * Stage (theatre), a space for the performance of theatrical productions * Theatre, a branch of the performing arts, often referred to as "the stage" * ''The Stage'', a weekly Brit ...

s. While Audio Networking bears a resemblance to

voice over IP Voice over Internet Protocol (VoIP), also known as IP telephony, is a set of technologies used primarily for voice communication sessions over Internet Protocol (IP) networks, such as the Internet. VoIP enables voice calls to be transmitted as ...

(VoIP) and audio contribution over IP (ACIP), Audio Networking is intended for

high-fidelity High fidelity (hi-fi or, rarely, HiFi) is the high-quality reproduction of sound. It is popular with audiophiles and home audio enthusiasts. Ideally, high-fidelity equipment has inaudible noise and distortion, and a flat (neutral, uncolored) f ...

, low-latency

professional audio Professional audio, abbreviated as pro audio, refers to both an activity and a category of high-quality, studio-grade audio equipment. Typically it encompasses sound recording, sound reinforcement system setup and audio mixing, and studio mus ...

. Because of the fidelity and latency constraints, Audio Networking systems generally do not utilize

audio data compression In information theory, data compression, source coding, or bit-rate reduction is the process of encoding information using fewer bits than the original representation. Any particular compression is either lossy or lossless. Lossless compression ...

. Audio Networking systems use a much higher bit rate (typically 1 Mbit/s per channel) and much lower latency (typically less than 10 milliseconds) than VoIP. Audio Networking requires a high-performance network. Performance requirements may be met through use of a dedicated

local area network A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, campus, or building, and has its network equipment and interconnects locally managed. LANs facilitate the distribution of da ...

(LAN) or virtual LAN (VLAN), overprovisioning or

quality of service Quality of service (QoS) is the description or measurement of the overall performance of a service, such as a telephony or computer network, or a cloud computing service, particularly the performance seen by the users of the network. To quantitat ...

features. Some Audio Networking systems use proprietary

protocols Protocol may refer to: Sociology and politics * Protocol (politics), a formal agreement between nation states * Protocol (diplomacy), the etiquette of diplomacy and affairs of state * Etiquette, a code of personal behavior Science and technology ...

(at the lower OSI layers) which create

Ethernet frame In computer networking, an Ethernet frame is a data link layer protocol data unit and uses the underlying Ethernet physical layer transport mechanisms. In other words, a data unit on an Ethernet link transports an Ethernet frame as its paylo ...

s that are transmitted directly onto the Ethernet (

layer 2 The data link layer, or layer 2, is the second layer of the seven-layer OSI model of computer networking. This layer is the protocol layer that transfers data between nodes on a network segment across the physical layer. The data link layer pr ...

) for

efficiency Efficiency is the often measurable ability to avoid making mistakes or wasting materials, energy, efforts, money, and time while performing a task. In a more general sense, it is the ability to do things well, successfully, and without waste. ...

and reduced overhead. The

word clock In digital audio electronics, a word clock or wordclock (sometimes sample clock, which can have a broader meaning) is a clock signal used to synchronise other devices, such as digital audio tape machines and compact disc players, which inter ...

may be provided by

broadcast packet In computer networking, telecommunication and information theory, broadcasting is a method of transferring a message to all recipients simultaneously. Broadcasting can be performed as a high-level operation in a program, for example, broadcast ...

Protocols

There are several different and incompatible protocols for Audio Networking. Protocols can be broadly categorized into

layer-1 In the seven-layer OSI model of computer networking, the physical layer or layer 1 is the first and lowest layer: the layer most closely associated with the physical connection between devices. The physical layer provides an electrical, mechani ...

layer-2 The data link layer, or layer 2, is the second layer of the seven-layer OSI model of computer networking. This layer is the protocol layer that transfers data between nodes on a network segment across the physical layer. The data link layer p ...

and

layer-3 In the seven-layer OSI model of computer networking, the network layer is layer 3. The network layer is responsible for packet forwarding including routing through intermediate routers. Functions The network layer provides the means of transf ...

systems based on the layer in the

OSI model The Open Systems Interconnection (OSI) model is a reference model developed by the International Organization for Standardization (ISO) that "provides a common basis for the coordination of standards development for the purpose of systems inter ...

where the protocol exists.

Layer-1 protocols

Layer-1 protocols use Ethernet wiring and signaling components but do not use the Ethernet frame structure. Layer-1 protocols often use their own

media access control In IEEE 802 LAN/MAN standards, the medium access control (MAC), also called media access control, is the layer that controls the hardware responsible for interaction with the wired (electrical or optical) or wireless transmission medium. Th ...

(MAC) rather than the one native to Ethernet, which generally creates compatibility issues and thus requires a dedicated network for the protocol.

Open standards

* AES50 (SuperMAC) by Klark Teknik, a point-to-point interconnect for bidirectional digital audio and sync clock * MaGIC by Gibson

Proprietary

*HyperMAC, a

gigabit Ethernet In computer networking, Gigabit Ethernet (GbE or 1 GigE) is the term applied to transmitting Ethernet frames at a rate of a gigabit per second. The most popular variant, 1000BASE-T, is defined by the IEEE 802.3ab standard. It came into use in ...

variant of SuperMAC * A-Net by Aviom *AudioRail *ULTRANET By

Behringer Behringer is an audio equipment company founded by the Swiss engineer Uli Behringer on 25 January 1989 in Willich, Germany. Behringer produces equipment including synthesizers, mixers, audio interfaces and amplifiers. Behringer is owned b ...

Layer-2 protocols

Layer-2 protocols encapsulate audio data in standard Ethernet frames. This is called Audio over Ethernet. Most protocols make use of standard Ethernet hubs and switches, though some require that the network (or at least a VLAN) be dedicated to the audio distribution application.

Open standards

AES51 AES51 is a standard first published by the Audio Engineering Society in June 2006 that specifies a method of carrying Asynchronous Transfer Mode (ATM) cells over Ethernet physical structure intended in particular for use with AES47 to carry AES3 ...

, a method of passing ATM services over Ethernet that allows

AES3 AES3 is a technical standard, standard for the exchange of digital audio signals between professional audio devices. An AES3 signal can carry two channels of pulse-code modulation, pulse-code-modulated digital audio over several transmission medi ...

audio to be carried in a similar way to

AES47 AES47 is a standard which describes a method for transporting AES3 professional digital audio streams over Asynchronous Transfer Mode (ATM) networks. The Audio Engineering Society (AES) published AES47 in 2002. The method described by AES47 is ...

Audio Video Bridging Audio Video Bridging (AVB) is a common name for a set of technical standards that provide improved synchronization, low latency, and reliability for switched Ethernet networks. AVB embodies the following technologies and standards: * IEEE 802 ...

(AVB), when used with the IEEE 1722 AV Transport Protocol profile (which transports

IEEE 1394 IEEE 1394 is an interface standard for a serial bus for high-speed communications and isochronous real-time data transfer. It was developed in the late 1980s and early 1990s by Apple in cooperation with a number of companies, primarily Sony a ...

/ IEC 61883 (FireWire) over Ethernet frames, using IEEE 802.1AS for timing)

Proprietary

CobraNet CobraNet is a combination of software, hardware, and network protocols designed to deliver Audio data compression, uncompressed, multi-channel, Latency (audio), low-latency digital audio over a standard Ethernet network. Developed in the 1990s, ...

**RAVE by QSC Audio, an implementation of CobraNet * EtherSound by Digigram **NetCIRA, a rebranded EtherSound by Fostex *REAC and RSS digital snake technology by

Roland Roland (; ; or ''Rotholandus''; or ''Rolando''; died 15 August 778) was a Frankish military leader under Charlemagne who became one of the principal figures in the literary cycle known as the Matter of France. The historical Roland was mil ...

* SoundGrid by

Waves Audio Waves Audio Ltd. is an Israeli developer and supplier of professional digital audio signal processing technologies and audio effects, used in recording, mixing, mastering, post production, broadcast, and live sound. The company's corporate headq ...

*dSNAKE by Allen & Heath

Layer-3 protocols

Layer-3 protocols encapsulate audio data in OSI model layer 3 (

network layer In the seven-layer OSI model of computer networking, the network layer is layer 3. The network layer is responsible for packet forwarding including routing through intermediate Router (computing), routers. Functions The network layer provides t ...

) packets. By definition it does not limit the choice of protocol to be the most popular layer-3 protocol, the

Internet Protocol The Internet Protocol (IP) is the network layer communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet. IP ...

(IP). In some implementations, the layer-3 audio data packets are further packaged inside OSI model layer-4 (

transport layer In computer networking, the transport layer is a conceptual division of methods in the layered architecture of protocols in the network stack in the Internet protocol suite and the OSI model. The protocols of this layer provide end-to-end c ...

) packets, most commonly

User Datagram Protocol In computer networking, the User Datagram Protocol (UDP) is one of the core communication protocols of the Internet protocol suite used to send messages (transported as datagrams in Network packet, packets) to other hosts on an Internet Protoco ...

(UDP) or

Real-time Transport Protocol The Real-time Transport Protocol (RTP) is a network protocol for delivering audio and video over IP networks. RTP is used in communication and entertainment systems that involve streaming media, such as telephony, video teleconference applic ...

(RTP). Use of UDP or RTP to carry audio data enables them to be distributed through standard computer routers, thus a large distribution audio network can be built economically using commercial off-the-shelf equipment. Although IP packets can traverse the

Internet The Internet (or internet) is the Global network, global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a internetworking, network of networks ...

, most layer-3 protocols cannot provide reliable transmission over the Internet due to the limited

bandwidth Bandwidth commonly refers to: * Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range * Bandwidth (computing), the rate of data transfer, bit rate or thr ...

, significant

End-to-end delay End-to-end delay or one-way delay (OWD) refers to the time taken for a Packet (information technology), packet to be transmitted across a computer network, network from source to destination. It is a common term in IP network monitoring, and differ ...

and

packet loss Packet loss occurs when one or more packets of data travelling across a computer network fail to reach their destination. Packet loss is either caused by errors in data transmission, typically across wireless networks, or network congestion.Ku ...

that can be encountered by data flow over the Internet. For similar reasons, transmission of layer-3 audio over

wireless LAN A wireless LAN (WLAN) is a wireless computer network that links two or more devices using wireless communication to form a local area network (LAN) within a limited area such as a home, school, computer laboratory, campus, or office building ...

are also not supported by most implementations.

Open standards

* AES67 * Audio Contribution over IP standardized by the

European Broadcasting Union The European Broadcasting Union (EBU; , UER) is an alliance of Public broadcasting, public service media organisations in countries within the European Broadcasting Area (EBA) or who are member states of the Council of Europe, members of the ...

(AVB), when used with IEEE 1733 or AES67 (which uses standard RTP over UDP/IP, with extensions for linking IEEE 802.1AS

Precision Time Protocol The Precision Time Protocol (PTP) is a protocol for clock synchronization throughout a computer network with relatively high precision and therefore ''potentially'' high accuracy. In a local area network (LAN), accuracy can be sub-microsecon ...

timing information to payload data) *NetJack, a network backend for the JACK Audio Connection Kit
Zita-njbridge
a set of clients for the JACK Audio Connection Kit *

RAVENNA Ravenna ( ; , also ; ) is the capital city of the Province of Ravenna, in the Emilia-Romagna region of Northern Italy. It was the capital city of the Western Roman Empire during the 5th century until its Fall of Rome, collapse in 476, after which ...

by ALC NetworX (uses PTPv2 timing)

Proprietary

* Livewire by Axia Audio, a division of

Telos Systems Telos Alliance is an American corporation manufacturing audio products primarily for broadcast stations. Headquartered in Cleveland, Ohio, US, the company is divided into six divisions: * Telos Systems manufactures talkshow systems, IP audio co ...

Dante Dante Alighieri (; most likely baptized Durante di Alighiero degli Alighieri; – September 14, 1321), widely known mononymously as Dante, was an Italian Italian poetry, poet, writer, and philosopher. His ''Divine Comedy'', originally called ...

by Audinate ( PTP version 1 timing) * Q-LAN by QSC Audio Products (PTP version 2 timing) *WheatNet-IP by Wheatstone Corporation

Similar concepts

High quality digital audio distribution was patented in 1988 by Tareq Hoque at the

MIT Media Lab The MIT Media Lab is a research laboratory at the Massachusetts Institute of Technology, growing out of MIT's Architecture Machine Group in the MIT School of Architecture and Planning, School of Architecture. Its research does not restrict to fi ...

. The technology was licensed to several leading OEM audio and chip manufacturers that were further developed into commercial products. RockNet by Riedel Communications, uses Cat-5 cabling. Hydra2 by Calrec uses Cat-5e cabling or fiber through SFP transceivers.

MADI Multichannel Audio Digital Interface (MADI) standardized Standardization (American English) or standardisation (British English) is the process of implementing and developing technical standards based on the consensus of different parties ...

uses 75-

ohm Ohm (symbol Ω) is a unit of electrical resistance named after Georg Ohm. Ohm or OHM may also refer to: People * Georg Ohm (1789–1854), German physicist and namesake of the term ''ohm'' * Germán Ohm (born 1936), Mexican boxer * Jörg Ohm (1 ...

coaxial cable Coaxial cable, or coax (pronounced ), is a type of electrical cable consisting of an inner Electrical conductor, conductor surrounded by a concentric conducting Electromagnetic shielding, shield, with the two separated by a dielectric (Insulat ...

with

BNC connector The BNC connector is a miniature quick-connect/disconnect RF connector, radio-frequency connector for coaxial cable. It was introduced on military radio equipment in the 1940s, and has since become widely used in radio systems and as a common t ...

s or optical fibre to carry up to 64 channels of digital audio in a point-to-point connection. It is most similar in design to

, which can carry only two channels.

provides audio networking by passing AES3 audio transport over an ATM network using structured network cabling (both copper and fibre). This was used extensively by contractors supplying the

BBC The British Broadcasting Corporation (BBC) is a British public service broadcaster headquartered at Broadcasting House in London, England. Originally established in 1922 as the British Broadcasting Company, it evolved into its current sta ...

's wide area real-time audio connectivity around the UK. Audio Contribution over IP differs in that it works at a higher layer, encapsulated within Internet Protocol. Some of these systems are usable on the Internet, but may not be as instantaneous, and are only as reliable as the network route — such as the path from a

remote broadcast In broadcast engineering, a remote broadcast (usually just called a remote or a live remote, or in news parlance, a live shot) is broadcasting done from a location away from a formal television or radio studio and is considered an electronic fiel ...

back to the main studio, or the

studio/transmitter link A studio transmitter link (STL) sends a radio station's or television station's audio and video from the broadcast studio or origination facility to a radio transmitter, television transmitter or uplink facility in another location. This is accom ...

(STL), the most critical part of the

airchain In broadcast engineering for radio or television, the airchain or transmission chain (UK) (sometimes air chain (US) or just chain (UK)) is the path or route an audio or video signal takes on its way through a radio station or television station. ...

. This is similar to VoIP, however ACIP is comparable to AoIP for a small number of channels, which are usually also data-compressed. Reliability for permanent STL uses comes from the use of a

virtual circuit A virtual circuit (VC) is a means of transporting data over a data network, based on packet switching and in which a connection is first established across the network between two endpoints. The network, rather than having a fixed data rate reser ...

, usually on a

leased line A leased line is a private telecommunications circuit between two or more locations provided according to a commercial contract. It is sometimes also known as a private circuit, and as a data line in the UK. Typically, leased lines are used by ...

such as T1/ E1, or at minimum

ISDN Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the digitalised circuits of the public switched telephone network. ...

DSL Digital subscriber line (DSL; originally digital subscriber loop) is a family of technologies that are used to transmit digital data over telephone lines. In telecommunications marketing, the term DSL is widely understood to mean asymmetric di ...

. In broadcasting, and to some extent in studio and even live production, many

manufacturer Manufacturing is the creation or Production (economics), production of goods with the help of equipment, Work (human activity), labor, machines, tools, and chemical or biological processing or formulation. It is the essence of the secondary se ...

s equip their own audio engines to be tied together. This may also be done with

and optical fibre rather than wire. This allows each studio to have its own engine, or for auxiliary studios to share an engine. By connecting them together, different sources can be shared among them. Audio Networking is not necessarily intended for

wireless network A wireless network is a computer network that uses wireless data connections between network nodes. Wireless networking allows homes, telecommunications networks, and business installations to avoid the costly process of introducing cables int ...

s, thus the use of various 802.11 devices may or may not work with various (or any) Audio Networking protocols.

References

{{Ethernet Audio engineering Broadcast engineering Ethernet Audio network protocols

Protocols

Layer-1 protocols

Open standards

Proprietary

Layer-2 protocols

Open standards

Proprietary

Layer-3 protocols

Open standards

Proprietary

Similar concepts

See also

References