Audio over IP

Audio over IP (AoIP) is the distribution of digital audio across an IP network such as the Internet. It is being 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 and latency are key issues for contribution links.

In the past, these links have made use of ISDN services but these are becoming increasingly difficult or expensive to obtain in some parts of Europe and are being phased out in others. Many proprietary systems came into existence for transporting high-quality audio over IP based on , or . An interoperable standard for audio over IP using RTP now exists.

Within a single building or music venue, audio over Ethernet (AoE) is more likely to be used instead, avoiding audio data compression and, in some cases, IP encapsulation.

The European Broadcasting Union (EBU) together with many equipment manufacturers has defined a common framework for audio contribution over IP in order to achieve interoperability between products. The frameworks define RTP as a common protocol and media payload type formats according to IETF definitions. is used as signalling for call setup and control. The recommendation is currently 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 buffering, forward error correction and error concealment to minimise latency and maximise packet streaming stability in live broadcast situations over unmanaged IP networks.

Due to the exhaustion of IPv4 IP addresses, IP audio codecs should now also be IPv6 compatible to ensure they 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.

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