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 set of communication protocols used in the Internet and similar computer networks according to functional criteria. The foundational protocols in the suit ...

such as the

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

. 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 gaug ...

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. Work ...

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 protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol (IP). Therefore, the entire suite is commonl ...

(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 packets) to other hosts on an Internet Protocol (IP) netwo ...

(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 applicati ...

(RTP). An interoperable standard for audio over IP using RTP has been published by the

European Broadcasting Union The European Broadcasting Union (EBU; french: Union européenne de radio-télévision, links=no, UER) is an alliance of public service media organisations whose countries are within the European Broadcasting Area or who are members of the C ...

(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. ...

audio over Ethernet In audio 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. AoE replaces bulky snake cables or audio-specific ...

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 compressi ...

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 and is responsible for the technical standards that make up the Internet protocol suite (TCP/IP). It has no formal membership roster or requirements an ...

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 signific ...

ing,

forward error correction In computing, telecommunication, information theory, and coding theory, an error correction code, sometimes error correcting code, (ECC) is used for controlling errors in data over unreliable or noisy communication channels. The central idea i ...

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 in multiple small packets. Packet ...

to minimise latency and maximise packet streaming stability in live broadcast situations over unmanaged IP networks. In the face of IPv4 address exhaustion,

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

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 distribution of audio or video content to a dispersed audience via any electronic mass communications medium, but typically one using the electromagnetic spectrum (radio waves), in a one-to-many model. Broadcasting began wi ...

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

radio Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a tr ...

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 device or computer program 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 on a signal or ...

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) 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 studio and is considered an electronic field producti ...

s, as

studio/transmitter link A studio transmitter link (or 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 ...

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 is wide bandwidth data transmission which transports multiple signals at a wide range of frequencies and Internet traffic types, that enables messages to be sent simultaneously, used in fast internet connections. ...

IP networks and wireless 3G,

3.5G High Speed Packet Access (HSPA) is an amalgamation of two mobile protocols—High Speed Downlink Packet Access (HSDPA) and High Speed Uplink Packet Access (HSUPA)—that extends and improves the performance of existing 3G mobile telecommunica ...

, 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 X.21 (sometimes referred to as X21) is an interface specification for differential communications introduced in the mid-1970s by the ITU-T. X.21 was first introduced as a means to provide a digital signaling interface for telecommunications bet ...

and POTS/

PSTN The public switched telephone network (PSTN) provides infrastructure and services for public telecommunication. The PSTN is the aggregate of the world's circuit-switched telephone networks that are operated by national, regional, or local teleph ...

. 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 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 should not be confused wi ...

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 over time from generally being built on physical connections between individual hardware cables, as in an analog phone swi ...

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 began using audio contribution over IP in Scotland as part of the

BBC Pacific Quay BBC Pacific Quay is BBC Scotland's television and radio studio complex at Pacific Quay, Glasgow, Scotland. Opened by then Prime Minister Gordon Brown on 20 September 2007, the studios are home to BBC Scotland's television, radio and online se ...

development in

Glasgow Glasgow ( ; sco, Glesca or ; gd, Glaschu ) is the most populous city in Scotland and the fourth-most populous city in the United Kingdom, as well as being the 27th largest city by population in Europe. In 2020, it had an estimated popu ...

. A similar system has been installed in the

Regions of England The regions, formerly known as the government office regions, are the highest tier of sub-national division in England, established in 1994. Between 1994 and 2011, nine regions had officially devolved functions within government. While they n ...

and will be installed in Wales and Northern Ireland. The audio packets are sent using UDP over the BBC's Layer-3 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 (Hindi: 2010 राष्ट्रमण्डल खेल), officially known as the XIX Commonwealth Games and commonly known as Delhi 2010, was an international multi-sport event that was held in Delhi, India, ...

hosted in India. Codecs such as the

Tieline Tieline Technology has offices in Indianapolis in the United States (Tieline America LLC) and in Perth, Western Australia (Tieline Pty Ltd). The company has a wide and established distribution network throughout Europe, the Americas and Austral ...

i-Mix G3 have been used since 2004 at the

Olympic Games The modern Olympic Games or Olympics (french: link=no, Jeux olympiques) are the leading international sporting events featuring summer and winter sports competitions in which thousands of athletes from around the world participate in a multi ...

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 local area networking of devices and Internet access, allowing nearby digital devices to exchange data by radio wa ...

, as well as other audio transports like POTS,

satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioiso ...

and

, and have been used at

UEFA Union of European Football Associations (UEFA ; french: Union des associations européennes de football; german: Union der europäischen Fußballverbände) is one of six continental bodies of governance in association football. It governs fo ...

and

FIFA World Cup The FIFA World Cup, often simply called the World Cup, is an international association football competition contested by the senior men's national teams of the members of the ' ( FIFA), the sport's global governing body. The tournament has ...

tournaments. Ultra portable audio-over-IP codecs are also available as a smartphone applications to send high fidelity broadcast quality audio from remote sites to studios. Applications such as Report-IT Live for iPhone 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. Audio over IP is also used in scientific applications, such as the

Neumayer Station Neumayer-Station III, also known as Neumayer III after geophysicist Georg von Neumayer, is a German Antarctic research station of the Alfred-Wegener-Institut. It is located on the approximately thick Ekström Ice Shelf several kilometres south ...

in Antarctica, where Barix IP Audio encoders digitize and stream the complete audio spectrum captured by

hydrophones A hydrophone ( grc, ὕδωρ + φωνή, , water + sound) is a microphone designed to be used underwater for recording or listening to underwater sound. Most hydrophones are based on a piezoelectric transducer that generates an electric potenti ...

under water to the

Alfred Wegener Institute for Polar and Marine Research The Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research (German: ''Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung'') is located in Bremerhaven, Germany, and a member of the Helmholtz Association ...

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