Report of the meeting of SC-02-02 Working Group on digital input/output interfacing of the SC-02 Subcommittee on Digital Audio, held in New York, NY., US., 2009-10-09
The meeting was chaired by vice chair S. Lyman.
The agenda was approved as written, although AES41-R was discussed first to suit A. Mason's schedule.
The previous report (from Munich) was approved as posted to the committee site.
[NOTE Where projects are not listed below, no action was requested or required.]
Review of Open Projects
Review of AES41-2000 (r2005): AES standard for digital audio - Recoding data set for audio bit-rate reduction
A late comment on the Munich draft was received from A. Borsum. The comment suggested that metadata for a multi-band compressor limiter could be added to the existing metadata for a single band compressor limiter. The problem with this is that if the intention is to use the multi-band device, there is no way to indicate that the metadata for the single band device should not be used. Even all-zeros metadata might still be interpreted as being valid.
J. Grant has proposed that the current draft be progressed to a CFC and that Borsum should propose text for a subsequent amendment.
Review of AES10-2003: AES Recommended Practice for Digital Audio Engineering - Serial Multichannel Audio Digital Interface (MADI)
No action requested or required.
The Secretariat reported that ITU-R is preparing a version of MADI restricted to 48-kHz sampling frequency specifically for broadcast applications. The AES has commented and will continue liaison.
Review of AES50-2005, High Resolution Multichannel Audio Interconnection (HRMAI)
A. Walker sent a note to the reflector with a number of changes that will be considered for revision of AES50. He has also proposed a more substantial revision to increase the speed of the interconnection to 1 Gb per second.
Review of AES-2id-2006: AES information document for digital audio engineering - Guidelines for the use of the AES3 interface
AES-2id will be revised to match the re-organized version of AES3, which is still in CFC. Once all parts of AES3 are published, further work on AES-2id will begin.
AES3 AES standard for digital audio - Digital input-output interfacing - Serial transmission format for two-channel linearly represented digital audio data, Parts 1 to 4
The revised draft for AES3 has been published as a Call for Comment (closes 2009-12-31). The group discussed various comments received which will be reported through the formal comments procedure.
AES5-R Review of AES5-2008: AES recommended practice for professional digital audio - Preferred sampling frequencies for applications employing pulse-code modulation
M. Karogosian has noted that AES3 refers normatively to the sampling frequencies listed in AES5, but that AES5 only Recommends the listed frequencies. He contended that a Standard cannot refer normatively to a Recommendation.
Several of the committee members felt that this is the strength of AES5, because mandating a limited set of sampling frequencies would be unnecessarily restrictive. It was also pointed out that IEC directives on normative references are not so restrictive.
Clarification will be sought from the SMPTE concerning their policy on normative references.
Development projects
AES-X139 Liaison with EBU P/AGA
It was reported that [EBU N/ACIP - Audio contribution over IP] has made two documents available for download. The first is EBU Tech 3326 - Interworking of Codecs over I/P networks. The second, EBU Tech 3329, is a tutorial on 3326.
AES-X182 AES/Ethernet Simple Open Protocol
A draft standard and explanatory report will be submitted by U. Zanghieri by the end of November 2009.
Liaisons
There were no other liaison matters.
New Projects
No new projects were proposed
New Business
No new business was proposed.
The next meeting will be held in conjunction with the AES 128th Convention in London, UK, 2010-05.
