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, 2007-10-04
The meeting was convened by chair J. Grant.
The agenda and report of the previous meeting, 2007-05-04, were accepted as written.
Open projects were discussed; those for which no action was proposed are not reported here.
AES-3id-R: Review of AES-3id-2001 (r2006): AES information document for digital audio engineering - Transmission of AES3 formatted data by unbalanced coaxial cable
The unbalanced connection for AES3 needs provision for higher frequencies, but this will be done as part of AES3-X rather than by amending AES-3id, which will be withdrawn when the restructured AES3 is published.
AES-X159: Carriage of PCM with MPEG Surround data over AES3
The draft of 2007-08-17 is to be secretariat-formatted. Amendment to AES3 is proposed to allow signalling presence of "hidden" information in the audio signal (see below); a similar amendment to IEC 60958-3 will be proposed.
AES3-R: Review of AES3-2003: AES standard for digital audio engineering - Serial transmission format for two channel linearly represented digital audio data
The current AES3 document needs an amendment to accommodate AES-X159, as proposed in postings to the reflector on 12th May and 3rd September. Secretariat will draft the amendment from the material in these mails, including AES41 as a protected format in Note 2.
AES3-X: Restructure of AES3-2003: AES standard for digital audio engineering - Serial transmission format for two channel linearly represented digital audio data
The current draft was posted 2007-09-10. There have been no comments on the reflector, and concern was expressed that this might mean no-one has read the drafts. C. Plachta offered to assist with drafting, particularly completing the sentence in clause 5 of AES3-3 (at the end of p.4).
AES-X121: Synchronisation of digital audio over wide areas
The meeting felt that the text of 2007-05-06 should be published as a report.
AES-X161: Digital interface for loudspeakers
No-one present had any information on progress since the Vienna meeting. Chair will ask S. Heinzmann for a progress report.
AES50-R: High Resolution Multichannel Audio Interconnection (HRMAI)
J. Oakley announced that Klark Teknik have acquired the SuperMAC and HyperMAC technology from Sony and expect to be involved in future maintenance of AES50 and AES-R6. He is interested in developing recommendations which would enhance interoperability by defining user profiles to carry, for example, 24 channels of audio at 24 bit x 96 kHz. M. Yonge suggested broadcasters might also want to use a 48 kHz sampling frequency. Oakley intends to propose HyperMAC (the 1 Gb/s version) for standardisation in the medium term.
AES-X139: Liaison with EBU P/AGA
R. Chalmers reported that EBU P/AGA had not met since he last reported, at the Vienna meeting. A joint EBU/SMPTE task group on A-V synchronisation has recently been formed; this appears to cover timing references, not AV sync. The EBU are also looking at channel assignments, and are aware of the SMPTE work (see below).
Liaisons
SMPTE
S. Lyman and P. Treleaven reported that a joint SMPTE and ATSC group are studying AV sync. SMPTE 320 (channel assignments) is to be replaced by SMPTE 2035 which lists rather more channel arrangements than SMPTE 320 but none with more than 8 channels.
IEC 60958-3
J. Yoshio reported that IEC 60958-3 will, with other groups, meet at the IEC TC100 meeting in Colmar, Alsace, France next week; they have proposals for additional information in channel status including higher sampling frequencies and more copy-control information. There is to be a new project on general channel assignment using the 3D model presented to SC-02-02 in Vienna, which supports formats such as 22.2.
EBU N/ACIP
P. Stevens reported that EBU N/ACIP (Audio Contribution over IP) expect to publish their recommendations this month, and are proposing to hold a plugfest in February 2008. EBU do not intend to offer a formal certification programme.
New Projects
No new projects were received or proposed.
New business
There was no new business.
The next meeting will be scheduled in conjunction with the 124th Convention in Amsterdam, Netherlands.
