AES Standards News Blog

It is with great sadness that we report the passing of Neil Gilchrist, an early leader in AES Standards development.

Neil joined the BBC after graduating from Manchester University in 1965 with a B.Sc. honors degree in physics and electronic engineering. He was a long-standing Lead Engineer at BBC Research, based at Kingswood Warren. There he worked on broadcast audio, PCM for national radio distribution, and NICAM for television sound. He was a world-renowned expert on audio and was considered to be one of R&D's 'golden ears'.

He participated in the EUREKA 147 (Digital Audio Broadcasting) project, and towards the end of his BBC career led the European ACTS ATLANTIC project to a successful conclusion in its final year. From 1981 to 1996 he represented the UK in the former CCIR, including chairmanship of CCIR Interim Working Party 10/6 (international exchange of sound programs). He represented the BBC on Sub-group V3 (Sound) of the EBU and served on both the AES and the EBU groups, which prepared the specification for the AES/EBU digital audio interface. He left the BBC in 2002 to work as a consultant in audio and broadcasting.

His AES activities have included frequent contributions to papers and workshop sessions at AES conventions and with Christer Grewin of the Swedish Broadcasting Corporation he assembled and edited the AES special publication Collected Papers on Digital Audio Bit-rate Reduction. In 1995 the AES awarded him a Fellowship for "important contributions to digital audio technology and standards activities." Neil was chairman of the AES British Section from 1990 to 1991 and he served as governor on the AES Board from 1999 to 2001 and 2008 to 2009. He served as President of the Society in 2006.

Neil was always an active member of any committee he was part of and was known for being meticulous about detail. He often referred to himself as the "Ship's Lawyer" and could be relied upon to keep things moving in the right direction. He was good company and had a great sense of humor.

In 1967 he married Susan Bixley a professional musician and they had two children Lizzie and Stephen. Neil's great interest in life as well as his family and electronics was music. He was an excellent amateur bassoon player who had been a member of the National Youth Orchestra and occasionally played professionally. Neil played in the Surrey Philharmonic Orchestra and was the orchestra's administrator for many years until his death. Neil was also a keen gardener, particularly growing vegetables and he used his scientific mind to ensure everything was grown to its full potential.

Neil died suddenly from a heart attack, aged 80, on 17 September 2024 while walking to the local shops. He leaves his wife Susan, children Lizzie and Stephen and two grandchildren Charlotte and James.

AES74-2019: AES standard for audio applications of networks — Requirements for Media Network Directories and Directory Services

This document sets forth technical recommendations for media network directories and directory-related services and mechanisms such as network discovery. It is hoped that this document will inform future industry directory and directory services standards that cover at least the following topics:

1. Registration, query, and administration protocols;
2. Security mechanisms;
3. Directory data model;
4. Query language and related semantics; and
5. Scalability strategies.

It remains available for download in the AES Standards Store.

Copies may be obtained here

AES3-1-2009: AES standard for digital audio — Digital input-output interfacing — Serial transmission format for two-channel linearly-represented digital audio data

AES3 provides for the serial digital transmission of two channels of periodically sampled and uniformly quantized audio signals on various media.

— Part 1: Audio Content: specifies the semantics of the audio data, including the "validity" flag. It also specifies the sampling frequency by reference to AES5.

— Part 2: Metadata and Subcode: specifies the information transmitted with the audio data: principally the "channel status" but also user data and the use of the auxiliary bits to carry a co-ordination signal.

— Part 3: Transport: specifies the framing and channel coding for transmission on a unidirectional point-to-point physical link. The specified format minimizes the direct-current (DC) component on the transmission line, facilitates clock recovery from the data stream, and makes the interface insensitive to the polarity of connections.

— Part 4: specifies the physical signals that convey the bit stream specified in Part 3. The current version covers electrical signals on twisted-pair and co-axial cables. Other media, including fibre optic, are under consideration.

Copies may be obtained here

AES31-4-2024 AES standard for network and file transport of audio - Part 4: XML Implementation of Audio Decision Lists has been published.  

This document provides a syntax mapping for AES31-3 Edit Decision Markup Language (EDML) to XML Schema Language. This facilitates the expansion of the Audio Decision List format to include non-ASCII characters and updates the format facilitating it’s implementation using standard XML parsers and tools. It also supports multi-byte chacter sets for human-readable metadata in all territories worldwide. This document includes both an XML schema definition and an XSLT implementation capable of transforming a conforming XML instance document back to EDML.

AES31-3 was published in 1999 to provide a long-term alternative to proliferating proprietary formats. It provided a convention for expressing edit data in text form in a manner that enabled simple and accurate computer parsing while retaining human readability. It also described a method for expressing time-code information in character notation and simple automation for stereo & surround panning and audio gain. These edit documents were known as Audio Decision Lists (ADL) and used an Edit Decision Markup Language (EDML).

The subsequent growth of XML offers a similar markup facility but with better availability of software tools for faster implementations. XML also offers support for multi-byte characters in human-readable metadata instead of the plain ASCII of EDML, opening implementation to a world-wide user community.

This document is a revision of AES31-4-2015.

Download a copy here

The Call for Comment on DRAFT REVISED AES67-xxxx, "AES standard for audio applications of networks - High-performance streaming audio-over-IP interoperability" was published 2023-12-28. 

More Information

The fall AES Standards Working Group meetings will be held the week of September 1 through October 4.  As has been the case for several years the meetings will be held online using Zoom.  Details and a complete schedule are available on the AES Standards website.  

See the schedule here

AES70 is a suite of standards for control and monitoring of devices in professional media networks. This standard, AES standard for Audio applications of networks - Open control architecture - Part 22: Using AES70 to manage Milan™ media transport defines an application of the Core AES70 specification for managing Milan™ media transport connections, and related synchronization and clocking mechanisms.  Other standards in the AES70 suite specify control and monitoring repertoire, control protocols, and media transport management applications.

AES70 does not specify a media transport scheme. Rather, it is designed to operate with media transport schemes such as the one specified by Milan™.

More Information

The Call for Comment on DRAFT AES70-21-xxxx Audio applications of networks - Open Control Architecture - Part 21: Using AES70 to manage AES67 and SMPTE ST 2110-30 media transport has been published.

The AES70 standard is a suite of standards, classified into two divisions. The Core Standards division, contains standards essential to all implementations of AES70; the Adaptation Standards division contains application-specific standards. This standard, AES standard for audio applications of networks - Open Control Architecture - Part 21: Using AES70 to manage AES67 and SMPTE ST 2110 30 media transport, is an Adaptation Standard.

A media network contains at least four sets of services:

· media transport: synchronized transportation of media data;

· control: controlling devices;

· directory: allowing devices and controllers to identify and discover each other;

· time: enabling media transport synchronization and control action timing.

A key function of the control set is connection management, i.e. control of the making, breaking, and operation of media transport connections and sessions. AES70 contains a rich set of connection management features. This Standard specifies a way of using those features to manage AES67 and SMPTE ST 2110-30 media transport connections and sessions.

Directory and time services are not part of this Standard.

More Information

A reaffirmed version of the following AES standard has been published:

AES56-2008: AES standard on acoustics - Sound source modeling - Loudspeaker polar radiation measurements

This standard describes how the measurements of loudspeaker polar radiation data shall be made and documented. This acquired data is suitable for application in room acoustic, electro-acoustic, and sound system predictions, and loudspeaker data sheets. 

This standard is available for sale now in the AES Standards Store

Copies may be obtained here

A reaffirmed version of the following AES standard has been published:

AES73id-2019:  AES information document for acoustics - Loudspeaker driver comparison chambers

Acoustic performance measurements on loudspeaker drivers that are measured in different sites or with different equipment or methods are subject to variations in accuracy and repeatability. Similarly, end-of-line loudspeaker test systems often utilize small, arbitrarily shaped, driver measurement chambers that do not correlate from line to line, or from site to site. This document is motivated by the need for engineers in different locations to share accurate measurement data on specific or same type loudspeaker drivers and addresses some of the factors affecting repeatability of measurements in different locations.

This standard is available for sale now in the AES Standards Store

Copies may be obtained here