Report of the SC-02-05 Working Group on Synchronization of the SC-02 Subcommittee on Digital Audio meeting, held in conjunction with the AES 115th Convention in New York, NY, US, on 2003-10-08

Chair R. Caine convened the meeting.

The agenda and the report of the meeting held on 2003-03 in Amsterdam were accepted as written.

Open projects

AES5-R: Review of AES5-2003 AES recommended practice for professional digital audio - Preferred sampling frequencies for applications employing pulse-code modulation
With AES5-2003 very recently published, there was no call for further revision. Caine thanked everyone for their efforts in bringing this latest revision to a successful conclusion. The project will be kept under review until 2008.

AES11-R, Revision of AES11-1997 AES recommended practice for digital audio engineering - Synchronization of digital audio equipment in studio operations
The Call for Comment period on revised draft AES11-20xx, published on 2003-07-10, had two days to run and could not be discussed.

A possible new annex describing the multirate synchronising scheme used in the BBC ATM project was discussed as a potential amendment.

Development projects

AES-X121 Synchronization of Digital Audio Over Wide Areas
The author of this document is unable to develop it further before 2003-12. Caine had previously posted an additional paragraph to the reflector concerning the need to flag the path to synchronization of a source, thus providing indication of its reliability, and this was briefly discussed.

Some questions need to be addressed. First, the paragraph about AES11 needs to be reworded. Second, there is a need to find a solution to the problem of setting the receive buffer to half-full when a connection is first made. Third, there is a need for a "how not to" paragraph or clause to illuminate some potential pitfalls.

S. Scott, S. Lyman, and Caine offered input. A report will be prepared by 2004-05, with the intent to produce a standard.

AES-X136 Date and Time in AES11
The discussion re-opened the question of the appropriate place to insert date and time in the reference signal. Scott and Lyman both felt that specific references to UMID were inappropriate and that the mapping of bits to match that of the UMID proposed in X111 "UMID in AES3" was not of any advantage. Using the two 32-bit areas in channel status allocated for time-of-day sample address count and local sample address count seemed to be preferred. It was agreed to demote the current goal to a report and to review the situation when all the options are laid out clearly. This report should be ready before the next convention.

New projects

No new projects were proposed.

New business

There was no new business.

The next meeting is scheduled to be held in conjunction with the AES 116th Convention in Berlin, Germany, 2004-05.