Audio over IP (AoIP) is the distribution of digital audio across an

IP network The Internet protocol suite, commonly known as TCP/IP, is a framework for organizing the communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suite are ...

such as 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 ...

. It is used increasingly to provide high-quality audio feeds over long distances. The application is also known as audio contribution over IP (ACIP) in reference to the programming contributions made by field reporters and remote events.

Audio quality Sound quality is typically an assessment of the accuracy, fidelity, or Intelligibility (communication), intelligibility of sound, audio output from an electronic device. Quality can be measured objectively, such as when tools are used to gau ...

and latency are key issues for contribution links. In the past, these links have made use of

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. ...

services but these have become increasingly difficult or expensive to obtain. Many proprietary systems came into existence for transporting high-quality audio over IP based on

Transmission Control Protocol The Transmission Control Protocol (TCP) is one of the main communications protocol, protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol (IP). Therefore, th ...

(TCP),

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). Most use many of the same protocols as are used by

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 ...

. An interoperable standard for audio over IP using RTP has been published 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 ...

(EBU). Within a single building or

music venue A music venue is any location used for a concert or musical performance. Music venues range in size and location, from a small coffeehouse for folk music shows, an outdoor bandshell or bandstand or a concert hall to an indoor sports stadium. Ty ...

audio over Ethernet In audio engineering, audio and broadcast engineering, broadcast engineering, Audio networking is the use of a Computer networking, network to distribute real-time digital audio. Audio Networking replaces bulky snake cables or audio-specific insta ...

is more likely to be used instead, avoiding

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 ...

and, in some cases, IP encapsulation.

Technology

The

(EBU) together with many equipment manufacturers defined a common framework for audio contribution over IP in order to achieve interoperability between products. The framework defines RTP as a common protocol and media payload type formats according to

IETF The Internet Engineering Task Force (IETF) is a standards organization for the Internet standard, Internet and is responsible for the technical standards that make up the Internet protocol suite (TCP/IP). It has no formal membership roster ...

definitions.

Session Initiation Protocol The Session Initiation Protocol (SIP) is a signaling protocol used for initiating, maintaining, and terminating communication sessions that include voice, video and messaging applications. SIP is used in Internet telephony, in private IP telepho ...

(SIP) is used for call setup and control. The recommendation is published as EBU Tech 3326–2007. More advanced audio codecs are capable of sending audio over unmanaged IP networks like the internet using automated

jitter buffer In electronics and telecommunications, jitter is the deviation from true periodicity of a presumably periodic signal, often in relation to a reference clock signal. In clock recovery applications it is called timing jitter. Jitter is a significa ...

ing,

forward error correction In computing, telecommunication, information theory, and coding theory, forward error correction (FEC) or channel coding is a technique used for controlling errors in data transmission over unreliable or noisy communication channels. The centra ...

and

error concealment Error concealment is a technique used in signal processing that aims to minimize the deterioration of signals caused by missing data, called packet loss. A signal is a message sent from a transmitter to a Receiver (radio), receiver in multiple small ...

to minimise latency and maximise packet streaming stability in live broadcast situations over unmanaged IP networks. In the face of

IPv4 address exhaustion IPv4 address exhaustion is the depletion of the pool of unallocated IPv4 addresses. Because the original Internet architecture had fewer than 4.3 1000000000 (number), billion addresses available, depletion has been anticipated since the late 19 ...

IPv6 Internet Protocol version 6 (IPv6) is the most recent version of the Internet Protocol (IP), the communication protocol, communications protocol that provides an identification and location system for computers on networks and routes traffic ...

capability ensures codecs are capable of connecting over new Internet infrastructure. IPv6 infrastructure is being widely deployed to deliver a virtually inexhaustible supply of IP addresses. IPv6 addressing makes it much easier for broadcast codecs to connect to each other directly and perform flexible multi-point connections over IP.

Codecs

broadcasting 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), ...

, an IP audio codec is used to send broadcast-quality audio over IP from remote locations to

radio Radio is the technology of communicating using radio waves. Radio waves are electromagnetic waves of frequency between 3 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmitter connec ...

and

television studio A television studio, also called a television production studio, is an installation room in which video productions take place, either for the production of live television and its recording onto video tape or other media such as SSDs, or for ...

s around the globe. A

codec A codec is a computer hardware or software component that encodes or decodes a data stream or signal. ''Codec'' is a portmanteau of coder/decoder. In electronic communications, an endec is a device that acts as both an encoder and a decoder o ...

that uses

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) may be used in

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 ...

s, as

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 ...

s (STLs) or for studio-to-studio audio distribution. IP audio codecs use audio compression algorithms to send high fidelity audio over both wired

broadband In telecommunications, broadband or high speed is the wide-bandwidth (signal processing), bandwidth data transmission that exploits signals at a wide spread of frequencies or several different simultaneous frequencies, and is used in fast Inter ...

IP networks and wireless 3G, 3.5G, 4G and 5G cellular broadband networks. Broadcasters are migrating to low-cost wired and wireless ''audio over IP'' instead of older and more costly fixed-line technologies such as

, X.21 and POTS/

PSTN The public switched telephone network (PSTN) is the aggregate of the world's telephone networks that are operated by national, regional, or local telephony operators. It provides infrastructure and services for public telephony. The PSTN consists ...

. ISDN and POTS/PSTN leased lines are also being phased out in Europe and Australia, increasing the push into IP technologies for audio broadcasting. IP networks are more flexible, cheaper to upgrade and just as reliable as older network technologies. As a result, broadcasters using IP codecs are able to design and operate more adaptable audio networks with streamlined workflows and reduced operating costs. The latest IP audio codecs can send broadcast audio over stereo

unicast Unicast is data transmission from a single sender (red) to a single receiver (green). Other devices on the network (yellow) do not participate in the communication. In computer networking, unicast is a one-to-one transmission from one point in ...

multicast In computer networking, multicast is a type of group communication where data transmission is addressed to a group of destination computers simultaneously. Multicast can be one-to-many or many-to-many distribution. Multicast differs from ph ...

and multiple unicast connections. Using multicast and multiple unicast connections, audio can be sent over IP networks from one IP audio codec to several destination audio codecs. IP codecs generally use SIP in order to connect to a variety of different codecs designed by different manufacturers. IP audio codecs are available for wired and wireless broadband IP codec solutions. IP audio codecs are used in professional studio transmitter links (STLs) and studio networking. Traditionally these links have been implemented using

telecommunication circuit A telecommunication circuit is a path in a telecommunications network used to transmit information. Circuits have evolved from generally being built on physical connections between individual hardware cables, as in an analog phone switch, to v ...

s contracted from telephone companies to provide fixed bandwidth. With the advent of IP technology, broadcasters have been reducing these operational costs by replacing their existing synchronous networks with packetized ones.

Examples of use

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 ...

began using audio contribution over IP in Scotland as part of the BBC Pacific Quay development in

Glasgow Glasgow is the Cities of Scotland, most populous city in Scotland, located on the banks of the River Clyde in Strathclyde, west central Scotland. It is the List of cities in the United Kingdom, third-most-populous city in the United Kingdom ...

. A similar system has been installed in the

Regions of England The regions of England, formerly known as the government office regions, are the highest tier of sub-national division in England. They were established in 1994 and follow the 1974–96 county borders. They are a continuation of the former 194 ...

and will be installed in Wales and Northern Ireland. The audio packets are sent using UDP over the BBC's

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 ...

network. To reduce the chance that the audio is corrupted,

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 ...

(QoS) is set to ensure that the packets are given priority over other network traffic. The platforms used are the WorldNet Oslo for multiple channel contribution and distribution with the WorldCast Horizon deployed in stereo drop-off locations. Audio over IP is even used for large sport events. More than 1000 Barix IP audio codecs were used to network the various venues of the

2010 Commonwealth Games The 2010 Commonwealth Games, officially known as the XIX Commonwealth Games and commonly known as Delhi 2010, were an international multi-sport event for the members of the Commonwealth that was held in Delhi, India, from 3 to 14 October 201 ...

hosted in India. Codecs such as the Tieline i-Mix G3 have been used since 2004 at the

Olympic Games The modern Olympic Games (Olympics; ) are the world's preeminent international Olympic sports, sporting events. They feature summer and winter sports competitions in which thousands of athletes from around the world participate in a Multi-s ...

for live sports broadcasting. These codecs also have the ability to send audio over wireless IP, i.e. 3G and

WiFi Wi-Fi () is a family of wireless network protocols based on the IEEE 802.11 family of standards, which are commonly used for Wireless LAN, local area networking of devices and Internet access, allowing nearby digital devices to exchange data by ...

, as well as other audio transports like POTS,

satellite A satellite or an artificial satellite is an object, typically a spacecraft, placed into orbit around a celestial body. They have a variety of uses, including communication relay, weather forecasting, navigation ( GPS), broadcasting, scient ...

and X.21, and have been used at

UEFA The Union of European Football Associations (UEFA ; ; ) is one of six continental bodies of governance in association football. It governs football, futsal and beach soccer, beach football in Europe and the List of transcontinental countries#A ...

and

FIFA World Cup The FIFA World Cup, often called the World Cup, is an international association football competition among the senior List of men's national association football teams, men's national teams of the members of the FIFA, Fédération Internatio ...

tournaments. Ultra-portable audio-over-IP codecs are also available as smartphone applications to send high-fidelity broadcast-quality audio from remote sites to studios. Applications such as Report-IT Live for

iPhone The iPhone is a line of smartphones developed and marketed by Apple that run iOS, the company's own mobile operating system. The first-generation iPhone was announced by then–Apple CEO and co-founder Steve Jobs on January 9, 2007, at ...

can send bidirectional 15 kHz quality audio live with automated jitter buffering, forward error correction and error concealment. They can also send 20 kHz quality audio recordings from the phone to a studio via

FTP The File Transfer Protocol (FTP) is a standard communication protocol used for the transfer of computer files from a server to a client on a computer network. FTP is built on a client–server model architecture using separate control and dat ...

. Audio over IP is also used in scientific applications, such as the Neumayer Station in Antarctica, where Barix IP Audio encoders digitize and stream the complete audio spectrum captured by

hydrophones A hydrophone () is a microphone designed for underwater use, for recording or listening to underwater sound. Most hydrophones contains a piezoelectric transducer that generates an electric potential when subjected to a pressure change, such as a ...

underwater to the Alfred Wegener Institute for Polar and Marine Research in Germany.

References

External links

EBU ACIP website
*
Tieline Website Explaining Audio Over IP

Why IPv6 Matters to Your Station

EBU - Tech 3326 for Audio Contribution over IP

EBU - Tech 3329 Tutorial on Audio Contribution over IP
{{DEFAULTSORT:Audio Over Ip Digital audio Open standards Audio network protocols Networking standards

Technology

Codecs

Examples of use

See also

References

External links