SC-02-02 meeting, 2006-05-19

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 Paris, France, 2006-05-19

The meeting was convened by chair J. Grant.

The agenda and the report of the previous meeting, 2005-10-06, were accepted as written.

Open projects

AES-R4-R: Review of AES-R4 2002: Guidelines for AES standard for digital audio - Digital input-output interfacing - Transmission of digital audio over asynchronous transfer mode (ATM) networks, AES47
Revision expected to complement recent revision of AES47. Grant to review the text and update any areas that are out-of-date.

AES-R6: Guidelines for AES standard for digital audio engineering - High-resolution multi-channel audio interconnection (HRMAI)
Propose to change title for clarity to, "Guidelines for AES50 (HRMAI)" No other action requested or required.

AES-2id-R: Review of AES-2id-1996 (r2001): AES information document for digital audio engineering - Guidelines for the use of the AES3 interface
Comments on recent major draft to be incorporated. Annex E (on alignment levels) should be deleted. Grant and M. Page to check clause 9 (on interfacing with other transports).

R. Caine will produce a revised PTD for comment, then to be secretariat-formatted as PWD.

AES-3id-R: Review of AES-3id-2001: AES information document for digital audio engineering - Transmission of AES3 formatted data by unbalanced coaxial cable
Proposed that this document should be reaffirmed now, and later withdrawn at such time as the new AES3 (incorporating all the material currently in AES-3id) is published.

AES-10id-R: Review of AES-10id-2005: AES information document for digital audio engineering - Engineering guidelines for the multichannel audio digital interface (MADI) AES10
No action requested or required.

AES3-R: Review of AES3-2003: AES Recommended practice for digital audio engineering - Serial transmission format for two channel linearly represented digital audio data
It is proposed to restructure this complex document in layered form. Intent for PTD in 2007.

It was noted that SC-05-02 now has a draft specification for fibre optic cable and connectors. D. Rottinghaus reported that SMPTE have defined a "special" SFP (small form pluggable) module for higher frequencies for HDTV. Redrafting to continue on a timescale to achieve a PTD in 2007.

AES5-R: Review of AES5-2003: AES recommended practice for professional digital audio - Preferred sampling frequencies for applications employing pulse-code modulation
No action requested or required.

AES10-R: Review of AES10-2003: AES Recommended Practice for Digital Audio Engineering - Serial Multichannel Audio Digital Interface (MADI)
No action requested or required. Clause 7.2 (fibre optic interfacing) should be revised or amended once SC-05-02's standard is stable.

AES11-R: Review of AES11-2003: AES Recommended Practice for Digital Audio Engineering - Synchronization of digital audio equipment in studio operations
No action requested or required.

AES18-R: Review of AES18-1996 (r2002): AES recommended practice for digital audio engineering - Format for the user data channel of the AES digital audio interface
No action requested or required

AES41-R : Review of AES41-2000 (r2005): AES standard for digital audio - Recoding data set for audio bit-rate reduction
No action requested or required

AES47-R: Review of AES47-2006: Digital audio in asynchronous transfer mode (ATM)
Expecting draft amendment to 6.1.3 to complement publication of AES-X148. Grant to draft amendment.

AES50-R: High Resolution Multichannel Audio Interconnection (HRMAI)
Page to draft amendment as proposed in his posting to the reflector of 4th May 2006.

AES52-R: Review of AES52-2006, Insertion of unique identifiers into the AES3 transport stream
This standard was published 2006-02-06; no further action requested or required.

It was noted that the format specified in AES52 can also be used to carry other metadata, and other proposals to carry metadata in the U-bit should use the same block structure, and be issued with unique codes for bits 0-3 of byte 0 chosen from the 13 values that are shown as reserved in AES52.

Development projects

AES-X139: Liaison with EBU P/AGA
The recent EBU P/AGA meeting was mostly concerned with loudness levels and lip sync, but a test signal with an AES3 format was also mentioned. We should make them aware of the content of AES-X148.

AES-X143: Transmission of asynchronous transfer mode (ATM) over an Ethernet physical layer
The Call for Comment for AES51-xxxb was published 2006-03-10. No action required

AES-X121: Synchronisation of digital audio over wide areas
No progress has been made on this draft for some time. There's a need to review whether this document should be published in its current state or the project retired.

AES-X148: Sample-accurate timing in AES47
WG comment has been requested prior to PCFC. There have been no comments following Grant's posting to the working group e-mail reflector of 2006-05-06, and there were none at the meeting. The meeting felt that the document was now ready to proceed to PCFC.


J. Yoshio reported that IEC 60958 has moved connectors for consumer use from Part 3 into Part 1, but connectors for professional use will remain in Part 4.

S. Heinzmann reported that a group in VDE (Germany) is developing a specification for control of active loudspeakers via AES3. There are three parts: (1) command set (MIDI), (2) how to encode the MIDI commands in the user-bits (see also discussion on AES52), and (3) how to get messages back from the speaker, for which a mechanism similar to clause 6 of AES42 has been suggested. Secretariat to contact Stefan Ha�sing at DKE in Frankfurt.

There were no other liaison issues.

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 AES 121st Convention in San Francisco, CA., US., 2006-10.

AES - Audio Engineering Society