Report of the meeting of the SC-02-02 working group on digital audio interfaces, of the subcommittee on digital audio, held in Berlin, Germany, 2014-04-26
The meeting was convenened by chair J. Grant.
The agenda, and the report of the previous meeting, held in New York, 2013-10-17, were approved as written.
AES3-x-R: Review of AES3-1-2009, AES standard for digital audio - Digital input-output interfacing - Serial transmission format for two-channel linearly represented digital audio data (four parts)
The action on the Secretariat and S. Heinzmann for Part 2 is transferred to AES-2id (see below).
These documents will be reaffirmed if there is no unresolved objection by the time of the Los Angeles Convention in October.
As a future revision for Part 4, J. Paul and M. Danielson indicated that they would propose text to improve the specifications, in particular to improve signal integrity at high bit rates, here and in AES-2id (see below).
AES-2id-R: Review of AES-2id-2006 (r2012): AES information document for digital audio engineering - Guidelines for the use of the AES3 interface
Secretariat and Heinzmann to review which fields of channel status should be modified when tunnelling through other transports; for example, to remove the indication that a signal is a DARS when conveying it over a link that will not maintain the necessary timing.
Paul and Danielson to propose text to improve recommendations re physical interfaces (see also AES3-4 above).
AES5-R Review of AES5-2008: AES recommended practice for professional digital audio - Preferred sampling frequencies for applications employing pulse-code modulation
The meeting proposed to remove reference to all sample rates other than 48 kHz from the Abstract, not just 32 kHz as previously proposed, by changing the second sentence to "Recognition is also given to other sampling rates in common use."
AES10-R: Review of AES10-2008: AES Recommended Practice for Digital Audio Engineering - Serial Multichannel Audio Digital Interface (MADI)
Danielson indicated that he would propose revisions regarding (1) jitter tolerance (2) recovery of word clock from the MADI signal, which is forbidden by subclause 6.2 but is now common practice and, under the correct conditions, will meet the requirements of AES11.
However, this standard needs to be reaffirmed immediately, as it is overdue for its 5-years review; any revision will follow as soon as it is ready.
AES11-R Review of AES11-2009: AES Recommended Practice for Digital Audio Engineering - Synchronization of digital audio equipment in studio operations.
Heinzmann presented the material in his e-mail circulated to the reflector on 25th April, but there was not enough time for a proper discussion of it. Please review it and send your comments to the reflector.
AES-R8: AES standards project report - Synchronisation of digital audio over wide areas
The action on the chair to propose revised text is still outstanding.
Development Projects
AES-X182: AES/Ethernet Simple Open Protocol
There was no adverse WG comment on the final TG draft when it was uploaded; the formal call for approval has now been issued to this working group.
AES-X196: Use of AES3 with high sampling rates to carry multi-channel audio
Secretariat action to format the two schemes as an Information Document is still outstanding.
AES-X213: MADI over twisted-pair cabling
Final draft is still awaited. Some doubt was expressed as to the need for this standard, when there are other ways of sending MADI over twisted pair which don't require a change to the format, although maybe they don't have as good EMC performance. The current draft does not make clear the rationale; K Gross to send one to the TG reflector. If you are interested in this topic, please join SC-02-02-L.
Liaisons:
J. Yoshio reported that IEC TC100 TA4 is amending IEC 60958 Parts 1 and 3 to support carriage of 22.2 format (24 channels) in a similar way to the X196 proposals. 8K-pixel SDI will carry 32 channels of audio.
New Projects:
No new projects were proposed
New Business:
There was no new business.
The next meeting will be held in conjunction with the 137th Convention in Los Angeles, 9 to 12 October 2014.
