Background

This article describes a standardised method of interconnecting digital audio over a telecommunication standard network. The development of standards for digitising analogue audio, as used to interconnect both professional and domestic equipment was started in the mid 1980’s within the Audio Engineering Society and the European Broadcasting Union. This culminated in the publishing of the AES3 standard (frequently also known as AES/EBU) for professional use as well as, using different physical connections as specified in IEC 60958, within the domestic “Hi-Fi” environment. This work has provided the most commonly used method for digitally interconnecting audio equipment worldwide using physically separate cables for each stereo audio connection. Established in 1948, the Audio Engineering Society (AES) draws its membership from amongst engineers, scientists, manufacturers and other organisations and individuals with an interest or involvement in the professional audio industry. ... The European Broadcasting Union (EBU), known in French as LUnion Européenne de Radio-Télévision (UER), and unrelated to the European Union, was formed February 12, 1950 by 23 broadcasting organizations from Europe and the Mediterranean at a conference in the coastal resort of Torquay in Devon... AES/EBU, for Audio Engineering Society / European Broadcasting Union, officially known as AES3, is a 1992 standard (revised in 1995, 1998, and 2003) for carrying digital audio signals between various devices. ... The digital audio standard frequently called AES/EBU, for Audio Engineering Society / European Broadcasting Union, that is officially known as AES3, was first published in 1992 as a standard (and revised in 1995, 1998, and 2003) for carrying digital audio signals between various devices. ...

Introduction

Many professional audio systems are now combined with telecommunication and IT technologies to provide new functionality, flexibility and connectivity over both local and wide area networks. AES47 was developed to provide a standardised method of transporting the existing standard for digital audio (AES3) over current telecommunication interconnection standards that provide a quality of service required by many professional low latency, uncompressed live audio uses. It may be used directly between specialist audio devices or in combination with telecommunication and computer equipment with suitable network interfaces and utilises the same physical structured cable used as standard by those networks.

AES47 details

AES47 (IEC 62365) is an open standard that specifies a method for packing AES3 professional digital audio streams over Asynchronous Transfer Mode networks. The details of these standards can be studied at the Audio Engineering Society standards web site by downloading courtesy copies of AES47-2006, AES-R4-2002 and AES3-2003. AES47 was originally published in 2002 and has been republished with minor revisions in February 2006. The change in thinking from traditional ATM network design is not to necessarily use ATM to pass IP traffic (apart from management traffic) but to use it in parallel with standard Ethernet structures to deal with extremely high performance secure media streams. From work carried out at the British Broadcasting Corporation’s (BBC) R&D department and published as White Paper 074, it has been established that this approach provides the necessary performance for professional media production. AES47 has been developed to allow the simultaneous transport and switched distribution of a large number of AES3 linear audio streams at different sample frequencies. AES47 can support any of the standard AES3 sample rates and word size. AES11 Annex D (the November 2005 printing or version of AES11-2003) shows an example method to provide isochronous timing relationships for distributed AES3 structures over asynchronous networks such as AES47 where reference signals may be locked to common timing sources such as GPS. An additional standard has been published by the Audio Engineering Society to extend AES3 digital audio carried as AES47 streams to enable this to be transported over standard physical Ethernet hardware. This additional standard is known as AES51-2006. IEC 62365 is a standard that specifies a method for packing AES3 professional digital audio streams over Asynchronous Transfer Mode newtorks. ... Asynchronous Transfer Mode (ATM) is a cell relay network protocol which encodes data traffic into small fixed-sized (53 byte; 48 bytes of data and 5 bytes of header information) cells instead of variable sized packets (sometimes known as frames) as in packet-switched networks (such as the Internet Protocol... The British Broadcasting Corporation (BBC, sometimes also known as the Beeb or Auntie) is the largest broadcasting corporation in the world, founded in 1922. ... The AES11 standard published by the Audio Engineering Society provides a systematic approach to the synchronization of digital audio signals. ... Isochronous means having an equal time difference or occurring simultaneously. ... Over fifty GPS satellites such as this NAVSTAR have been launched since 1978. ... Established in 1948, the Audio Engineering Society (AES) draws its membership from amongst engineers, scientists, manufacturers and other organisations and individuals with an interest or involvement in the professional audio industry. ... AES/EBU, for Audio Engineering Society / European Broadcasting Union, officially known as AES3, is a 1992 standard (revised in 1995, 1998, and 2003) for carrying digital audio signals between various devices. ... Ethernet is large and diverse family of frame-based computer networking technologies for local area networks (LANs). ... Introduction AES51 is a standard first published by the Audio Engineering Society in June 2006 (Official Site) that specifies a method of carrying ATM (Asynchronous Transfer Mode) cells over Ethernet physical structure intended in particular for use with AES47 to carry AES3 digital audio transport structure. ...