Audio over Ethernet
Encyclopedia
In audio engineering
and broadcast engineering
, Audio over Ethernet (sometimes AoE - not to be confused with ATA over Ethernet
) is the use of an Ethernet
-based network to distribute real-time digital audio
.
It is designed to replace bulky snake cables and fixed wiring, and instead use a standard network structured cabling
in a facility, providing a reliable backbone
for any audio application, such as for large-scale sound reinforcement in stadiums, airports and convention centers, multiple studio
s or stage
s.
While on the surface AoE bears a resemblance to Voice over IP
(VoIP), AoE is intended for high-fidelity, low-latency professional audio. Because of the fidelity and latency constraints, audio over Ethernet systems generally do not utilize audio data compression. AoE systems use a much higher bit rate (typically 1 Mbit per channel) and much lower latency (typically less than 10 milliseconds) than VoIP.
Audio over Ethernet requires a high performance network. Performance requirements may be met through use of a dedicated local-area network (LAN) or virtual LAN
(VLAN), Overprovisioning and/or Quality of service
features.
Most AoE systems use proprietary protocol(s)
(at the higher OSI
layers) which create data packets and data frames that are transmitted directly onto the Ethernet (layer 2) for efficiency
and reduced overhead
. The word clock
may be provided by broadcast packets.
and 100BASE-TX signaling at 100 Mbits/second, each link can generally transmit between 32 and 64 channels at a 48kHz sampling rate
. Some can handle other rates, such as 44.1kHz (CD-quality), 88.2 and 96kHz (2× oversampling
), even 192kHz (4×), as well as up to 32-bit
samples, with a corresponding reduction in channel capacity
. On some, this is accomplished through channel bonding, while others use individually-scalable channels.
AoE is not necessarily intended for wireless network
s, thus the use of various 802.11 devices may or may not work with various (or any) AoE protocols.
Protocols can be broadly categorized into Layer 1, Layer 2 and Layer 3 systems based on the lowest layer in the OSI model
where the protocol exists.
(MAC) rather than the one native to Ethernet, which generally creates Computer compatibility
issues.
for this capability).
's MADI
or AES10, although similar in function, uses 75-ohm
coaxial cable
with BNC connector
s instead. It is most similar in design to AES3, which can carry only two channels (stereo).
The Audio Engineering Society
's AES47
, provides linear audio networking by passing AES3 audio transport over an ATM network using structured network cabling (both copper and fibre). This is used extensively by contractors supplying the BBC
's wide area real-time audio connectivity around the UK.
In broadcasting and to some extent in studio and even live production, many manufacturers equip their own audio engines to be tied together with Ethernet. This may also be done with gigabit Ethernet
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. Logitek Audio is one such company using this approach.
An audio over IP
setup differs in that it works at a higher layer, encapsulate
d within Internet Protocol. 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
back to the main studio, or the studio/transmitter link
(STL), the most critical part of the airchain
. This is similar to VoIP, however AoIP is comparable to AoE 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
, usually on a leased line
such as T1
/E1, or at minimum ISDN or DSL.
Audio engineering
An audio engineer, also called audio technician, audio technologist or sound technician, is a specialist in a skilled trade that deals with the use of machinery and equipment for the recording, mixing and reproduction of sounds. The field draws on many artistic and vocational areas, including...
and broadcast engineering
Broadcast engineering
Broadcast engineering is the field of electrical engineering, and now to some extent computer engineering and information technology, which deals with radio and television broadcasting...
, Audio over Ethernet (sometimes AoE - not to be confused with ATA over Ethernet
ATA over Ethernet
ATA over Ethernet is a network protocol developed by the Brantley Coile Company, designed for simple, high-performance access of SATA storage devices over Ethernet networks. It is used to build storage area networks with low-cost, standard technologies.- Protocol description :AoE runs on layer 2...
) is the use of an Ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
-based network to distribute real-time digital audio
Digital audio
Digital audio is sound reproduction using pulse-code modulation and digital signals. Digital audio systems include analog-to-digital conversion , digital-to-analog conversion , digital storage, processing and transmission components...
.
It is designed to replace bulky snake cables and fixed wiring, and instead use a standard network structured cabling
Structured cabling
Structured cabling is building or campus telecommunications cabling infrastructure that consists of a number of standardized smaller elements called subsystems.Structured cabling falls into six subsystems:...
in a facility, providing a reliable backbone
Backbone network
A backbone network or network backbone is a part of computer network infrastructure that interconnects various pieces of network, providing a path for the exchange of information between different LANs or subnetworks. A backbone can tie together diverse networks in the same building, in different...
for any audio application, such as for large-scale sound reinforcement in stadiums, airports and convention centers, multiple studio
Studio
A studio is an artist's or worker's workroom, or the catchall term for an artist and his or her employees who work within that studio. This can be for the purpose of architecture, painting, pottery , sculpture, scrapbooking, photography, graphic design, filmmaking, animation, radio or television...
s or stage
Stage (theatre)
In theatre or performance arts, the stage is a designated space for the performance productions. The stage serves as a space for actors or performers and a focal point for the members of the audience...
s.
While on the surface AoE bears a resemblance to Voice over IP
Voice over IP
Voice over Internet Protocol is a family of technologies, methodologies, communication protocols, and transmission techniques for the delivery of voice communications and multimedia sessions over Internet Protocol networks, such as the Internet...
(VoIP), AoE is intended for high-fidelity, low-latency professional audio. Because of the fidelity and latency constraints, audio over Ethernet systems generally do not utilize audio data compression. AoE systems use a much higher bit rate (typically 1 Mbit per channel) and much lower latency (typically less than 10 milliseconds) than VoIP.
Audio over Ethernet requires a high performance network. Performance requirements may be met through use of a dedicated local-area network (LAN) or virtual LAN
Virtual LAN
A virtual local area network, virtual LAN or VLAN, is a group of hosts with a common set of requirements that communicate as if they were attached to the same broadcast domain, regardless of their physical location...
(VLAN), Overprovisioning and/or Quality of service
Quality of service
The quality of service refers to several related aspects of telephony and computer networks that allow the transport of traffic with special requirements...
features.
Most AoE systems use proprietary protocol(s)
Communications protocol
A communications protocol is a system of digital message formats and rules for exchanging those messages in or between computing systems and in telecommunications...
(at the higher OSI
OSI model
The Open Systems Interconnection model is a product of the Open Systems Interconnection effort at the International Organization for Standardization. It is a prescription of characterizing and standardizing the functions of a communications system in terms of abstraction layers. Similar...
layers) which create data packets and data frames that are transmitted directly onto the Ethernet (layer 2) for efficiency
Algorithmic efficiency
In computer science, efficiency is used to describe properties of an algorithm relating to how much of various types of resources it consumes. Algorithmic efficiency can be thought of as analogous to engineering productivity for a repeating or continuous process, where the goal is to reduce...
and reduced overhead
Computational overhead
In computer science, overhead is generally considered any combination of excess or indirect computation time, memory, bandwidth, or other resources that are required to attain a particular goal...
. The word clock
Word clock
A word clock or wordclock is a clock signal used to synchronise other devices, such as digital audio tape machines and compact disc players, which interconnect via digital audio. S/PDIF, AES/EBU, ADAT, and TDIF are some of the formats that use a word clock...
may be provided by broadcast packets.
Protocols
There are several different and incompatible protocols for audio over Ethernet. For example, using category 5 cableCategory 5 cable
Category 5 cable is a twisted pair cable for carrying signals. This type of cable is used in structured cabling for computer networks such as Ethernet. It is also used to carry other signals such as telephony and video. The cable is commonly connected using punch down blocks and modular connectors...
and 100BASE-TX signaling at 100 Mbits/second, each link can generally transmit between 32 and 64 channels at a 48kHz sampling rate
Sampling rate
The sampling rate, sample rate, or sampling frequency defines the number of samples per unit of time taken from a continuous signal to make a discrete signal. For time-domain signals, the unit for sampling rate is hertz , sometimes noted as Sa/s...
. Some can handle other rates, such as 44.1kHz (CD-quality), 88.2 and 96kHz (2× oversampling
Oversampling
In signal processing, oversampling is the process of sampling a signal with a sampling frequency significantly higher than twice the bandwidth or highest frequency of the signal being sampled...
), even 192kHz (4×), as well as up to 32-bit
Bit
A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...
samples, with a corresponding reduction in channel capacity
Channel capacity
In electrical engineering, computer science and information theory, channel capacity is the tightest upper bound on the amount of information that can be reliably transmitted over a communications channel...
. On some, this is accomplished through channel bonding, while others use individually-scalable channels.
AoE is not necessarily intended for wireless network
Wireless network
Wireless network refers to any type of computer network that is not connected by cables of any kind. It is a method by which homes, telecommunications networks and enterprise installations avoid the costly process of introducing cables into a building, or as a connection between various equipment...
s, thus the use of various 802.11 devices may or may not work with various (or any) AoE protocols.
Protocols can be broadly categorized into Layer 1, Layer 2 and Layer 3 systems based on the lowest layer in the OSI model
OSI model
The Open Systems Interconnection model is a product of the Open Systems Interconnection effort at the International Organization for Standardization. It is a prescription of characterizing and standardizing the functions of a communications system in terms of abstraction layers. Similar...
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 controlMedia Access Control
The media access control data communication protocol sub-layer, also known as the medium access control, is a sublayer of the data link layer specified in the seven-layer OSI model , and in the four-layer TCP/IP model...
(MAC) rather than the one native to Ethernet, which generally creates Computer compatibility
Computer compatibility
A family of computer models is said to be compatible if certain software that runs on one of the models can also be run on all other models of the family. The computer models may differ in performance, reliability or some other characteristic...
issues.
- A-Net by AviomAviomAviom is a pro audio equipment manufacturer of personal monitoring systems. Headquartered in West Chester, Pennsylvania, Aviom produces distributed audio networking gear which uses a proprietary digital audio transport system called A-Net, based on the physical layer of Ethernet and carried over...
- AES50
- SuperMACSupermacSupermac may refer to:* Harold Macmillan, , Prime Minister of the United Kingdom from 1957 to 1963* Malcolm "Supermac" Macdonald, , a retired English football player and pundit...
, an implementation of AES50
- SuperMAC
- AudioRail
- M11 by AudioRail
- MaGICMagicMagic may refer to:* Magic , the art of appearing to perform supernatural feats using sleight of hand or other methods* Magic , the use of paranormal methods to manipulate natural forces, such as witchcraft...
by GibsonGibson Guitar CorporationThe Gibson Guitar Corporation, formerly of Kalamazoo, Michigan and currently of Nashville, Tennessee, manufactures guitars and other instruments which sell under a variety of brand names... - RockNet by Riedel Communications
- ZIPI by Zeta Instruments/CNMATCNMATCNMAT , The Center for New Music and Audio Technologies, is a multidisciplinary research center within University of California, Berkeley Department of Music. The Center's goal is to provide a common ground where music, cognitive science, computer science, and other disciplines meet to...
Layer 2 protocols
Layer 2 protocols encapsulate audio data in standard Ethernet packets. Most can 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.- AES51AES51AES51 is a standard first published by the Audio Engineering Society in June 2006 that specifies a method of carrying ATM cells over Ethernet physical structure intended in particular for use with AES47 to carry AES3 digital audio transport structure...
, A method of passing ATM services over Ethernet that allows AES3 audio to be carried in a similar way to AES47AES47AES47 describes a standardised method for packing AES3 professional digital audio streams over Asynchronous Transfer Mode networks. The AES47 method is published by the International Electrotechnical Commission as IEC 62365.-Introduction:... - Audio Video BridgingAudio Video BridgingAudio Video Bridging is a common name for the set of technical standards developed by the Institute of Electrical and Electronics Engineers Audio Video Bridging Task Group of the IEEE 802.1 standards committee. The charter of this organization is to "provide the specifications that will allow...
(AVB) - CobraNetCobranetCobraNet is a combination of software, hardware and network protocols designed to deliver uncompressed, multi-channel, low-latency digital audio over a standard Ethernet network...
- RAVE by QSC AudioQSC Audio ProductsQSC Audio Products, LLC is an American manufacturer of professional audio products. QSC's target markets are audio professionals in concert, installation, portable entertainment and cinema applications.-History:...
- RAVE by QSC Audio
- EtherSoundEtherSoundEtherSound is one of several audio over Ethernet technologies currently used in audio engineering and broadcast engineering applications. EtherSound is developed and licensed by Digigram....
by Digigram- NetCIRA by FostexFostexFostex is a Japanese manufacturer that is one of the largest transducer and OEM speaker makers in the world, founded in July 1973 by Foster Electric Co. Ltd.-Company history:Fostex , founded in July 1973 by Foster Electric Co...
- NetCIRA by Fostex
- REAC by RolandRoland Corporationis a Japanese manufacturer of electronic musical instruments, electronic equipment and software. It was founded by Ikutaro Kakehashi in Osaka on April 18, 1972, with ¥33 million in capital. In 2005 Roland's headquarters relocated to Hamamatsu in Shizuoka Prefecture. Today it has factories in Japan,...
- Hydra by Calrec
Layer 3 protocols
Layer 3 protocols encapsulate audio data in standard IP packets (usually UDP/IP or RTP/UDP/IP). Use of the IP protocol improves interoperability with standard computing platforms and in some cases, improves scalability of the audio distribution system. The layer 3 audio over Ethernet protocols are not designed to traverse the Internet (see Audio over IPAudio over IP
Streaming audio over IP networks is being increasingly used by broadcasting companies, among others, to provide high-quality audio feeds over distance across an IP network such as the Internet. The application is also known as audio contribution over IP in reference to the programming...
for this capability).
- AoIP by Wheatstone Corp
- LivewireLivewire (networking)Livewire is an audio over Ethernet system created by Axia Audio a division of Telos Systems. Livewire was introduced in 2003 and is used primarily in radio station applications...
by Axia Audio, a division of Telos SystemsTelos SystemsTelos Systems is an American corporation manufacturing audio products primarily for broadcast stations. Headquartered in Cleveland, Ohio, USA, Telos develops, sells, and supports equipment such as telephone hybrids and on-air talkshow systems, ISDN codecs, POTS codecs, IP codecs, and audio logging... - DanteDante (networking)Dante is a combination of software, hardware and network protocols designed to deliver uncompressed, multi-channel, low-latency digital audio over a standard Ethernet network...
by Audinate - Q-LANQ-LANQ-LAN is the audio over Ethernet audio networking technology component of the Q-Sys audio signal processing platform from QSC Audio Products.-External links:*...
by QSC Audio ProductsQSC Audio ProductsQSC Audio Products, LLC is an American manufacturer of professional audio products. QSC's target markets are audio professionals in concert, installation, portable entertainment and cinema applications.-History:... - RAVENNA by ALC NetworX
Similar concepts
The Audio Engineering SocietyAudio Engineering Society
Established in 1948, the Audio Engineering Society draws its membership from amongst engineers, scientists, other individuals with an interest or involvement in the professional audio industry. The membership largely comprises engineers developing devices or products for audio, and persons working...
's MADI
MADI
Multichannel Audio Digital Interface, MADI or AES10 is an industry-standard electronic communications protocol that defines the data format and electrical characteristics of an interface carrying multiple channels of digital audio. The Audio Engineering Society standard for MADI was originally...
or AES10, although similar in function, uses 75-ohm
Ohm
The ohm is the SI unit of electrical resistance, named after German physicist Georg Simon Ohm.- Definition :The ohm is defined as a resistance between two points of a conductor when a constant potential difference of 1 volt, applied to these points, produces in the conductor a current of 1 ampere,...
coaxial cable
Coaxial cable
Coaxial cable, or coax, has an inner conductor surrounded by a flexible, tubular insulating layer, surrounded by a tubular conducting shield. The term coaxial comes from the inner conductor and the outer shield sharing the same geometric axis...
with BNC connector
BNC connector
The BNC connector ' is a common type of RF connector used for coaxial cable. It is used with radio, television, and other radio-frequency electronic equipment, test instruments, video signals, and was once a popular computer network connector. BNC connectors are made to match the characteristic...
s instead. It is most similar in design to AES3, which can carry only two channels (stereo).
The Audio Engineering Society
Audio Engineering Society
Established in 1948, the Audio Engineering Society draws its membership from amongst engineers, scientists, other individuals with an interest or involvement in the professional audio industry. The membership largely comprises engineers developing devices or products for audio, and persons working...
's AES47
AES47
AES47 describes a standardised method for packing AES3 professional digital audio streams over Asynchronous Transfer Mode networks. The AES47 method is published by the International Electrotechnical Commission as IEC 62365.-Introduction:...
, provides linear audio networking by passing AES3 audio transport over an ATM network using structured network cabling (both copper and fibre). This is used extensively by contractors supplying the BBC
BBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...
's wide area real-time audio connectivity around the UK.
In broadcasting and to some extent in studio and even live production, many manufacturers equip their own audio engines to be tied together with Ethernet. This may also be done with gigabit Ethernet
Gigabit Ethernet
Gigabit Ethernet is a term describing various technologies for transmitting Ethernet frames at a rate of a gigabit per second , as defined by the IEEE 802.3-2008 standard. It came into use beginning in 1999, gradually supplanting Fast Ethernet in wired local networks where it performed...
and optical fibre rather than wire
Wire
A wire is a single, usually cylindrical, flexible strand or rod of metal. Wires are used to bear mechanical loads and to carry electricity and telecommunications signals. Wire is commonly formed by drawing the metal through a hole in a die or draw plate. Standard sizes are determined by various...
. 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. Logitek Audio is one such company using this approach.
An audio over IP
Audio over IP
Streaming audio over IP networks is being increasingly used by broadcasting companies, among others, to provide high-quality audio feeds over distance across an IP network such as the Internet. The application is also known as audio contribution over IP in reference to the programming...
setup differs in that it works at a higher layer, encapsulate
Encapsulation (networking)
In computer networking, encapsulation is a method of designing modular communication protocols in which logically separate functions in the network are abstracted from their underlying structures by inclusion or information hiding within higher level objects....
d within Internet Protocol. These systems are usable on the Internet
Internet
The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
, but may not be as instantaneous, and are only as reliable as the network route — such as the path from a remote broadcast
Remote broadcast
In broadcast engineering, a remote broadcast is broadcasting done from a location away from a formal television studio and is considered an electronic field production . A remote pickup unit is usually used to transmit the audio and/or video back to the television station, where it joins the...
back to the main studio, or the studio/transmitter link
Studio/transmitter link
A studio-transmitter link sends a radio station's or television station's audio and video from the broadcast studio to a radio transmitter or television transmitter in another location....
(STL), the most critical part of the airchain
Airchain
In broadcast engineering for radio or television, the airchain or transmission chain is the path or route an audio or video signal takes on its way through a radio station or television station.The airchain begins with cameras, microphones, CD players, turntables, telephone hybrids, video tape...
. This is similar to VoIP, however AoIP is comparable to AoE 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
Virtual circuit
In telecommunications and computer networks, a virtual circuit , synonymous with virtual connection and virtual channel, is a connection oriented communication service that is delivered by means of packet mode communication...
, usually on a leased line
Leased line
A leased line is a service contract between a provider and a customer, whereby the provider agrees to deliver a symmetric telecommunications line connecting two or more locations in exchange for a monthly rent . It is sometimes known as a 'Private Circuit' or 'Data Line' in the UK or as CDN in Italy...
such as T1
Digital Signal 1
Digital signal 1 is a T-carrier signaling scheme devised by Bell Labs. DS1 is a widely used standard in telecommunications in North America and Japan to transmit voice and data between devices. E1 is used in place of T1 outside North America, Japan, and South Korea...
/E1, or at minimum ISDN or DSL.