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 London, UK, 2010-05-22
The meeting was convened by chair J. Grant.
The agenda was approved as written, noting that AES3-R has now been closed, having been superseded by the four projects AES3-1-R to AES3-4-R.
The previous report (from New York) was approved as posted to the web site.
The following active projects were discussed. [NOTE Where projects are not listed below, no action was requested or required.]
Review of Open Projects
AES11-R: Synchronization of digital audio equipment in studio operations.
References to AES3 have been updated to refer to AES3-4.
AES41-R: Recoding data set for audio bit-rate reduction
The objections to the Call for Comment have now been withdrawn, which will allow the current revision (which includes reporting of loudness and downmix) to be published. A further revision to include additional support for Dolby E can proceed as soon as a New Project Proposal has been received; this might extend the scope beyond bit-rate reduction, and might make it appropriate to separate out the encoding of the metadata as a bit string from the transportation of that bit string in linear PCM audio.
AES50-R: High-resolution multi-channel audio interconnection (HRMAI)
Apart from some faults in some of the diagrams, the current draft is ready to proceed to PWD. A Walker will check whether any revisions to AES-R6 are needed to bring it into line with the new draft. It is intended that there should be a further revision to extend the specification to support Gigabit as well as 100 Mb/s.
AES-2id-R: Guidelines for the use of the AES3 interface
R Caine proposed that references to AES3-2003 should be retained in parentheses, for the benefit of readers who are still using the older AES3 text.
AES3-4-R: Serial transmission format for two-channel linearly represented digital audio data Part 4: Physical and electrical
C. Chambers reported that BBC (in Broadcasting House) and Radio France have found that when several units are cascaded, each taking its timing from the AES3 input, jitter can build up sufficiently that the last link does not meet the specification. R Caine proposed that a warning should be added to AES3-4 that care is needed to prevent jitter accumulating where multiple units are cascaded. C Chambers and R Caine to propose text; this may also affect AES11 (which already mentions the problem in 4.2.2) and AES-2id.
Development projects
AES-X139: Liaison with EBU P/AGA
A. Mason reported that EBU's technical activities are now handled by Expert Communities (see <http://tech.ebu.ch/groups>), which non-members may also join. He chairs ECA-Audio which has taken over P/AGA's work. M. Yonge to write to EBU to let them know we are aware of the change.
AES-X182: AES/Ethernet Simple Open Protocol
U. Zanghieri reported that it was taking longer than expected to identify the minimum requirements for a node, i.e. to decide the details of the scope of the standard, and the new target for the draft is September 2010.
AES-X186: Liaison with ITU-R re draft BS.[MADI], derived from AES10-2008
the ITU-R subset of AES10 is now published; the main difference from AES10 is removal of all sampling frequencies above 48kHz. ITU-R are now working on a standard that will be a similar subset of the new 4-part AES3; their current BS.647 is aligned with an old version of AES3 (earlier than 2003).
Liaisons
J. Yoshio reported that a number of IEC meetings will be held on Monday 24th, including maintenance of 61937-1 and -2, new parts of 61937 including DRA (a Chinese technology used on Blu-Ray), maintenance of 60958-3, and a new version of 61883-6 which is aligned with Blu-Ray.
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 129th Convention in San Francisco, 2010-11.
