SC-02-12 meeting, 2006-05

Report of the meeting of the SC-02-12 Working Group on Audio Applications Using the High Performance Serial Bus (IEEE 1394) of the SC-02 Subcommittee on Digital Audio, held at the 120th AES Convention, Paris, 22 May 2006.

The meeting was convened by Chair J. Strawn.

The agenda and the report of the previous meeting were approved as written.

Development Projects

AES-X075: IEC Liaison for IEC-PAS 61883-6
IEC Liaison Report (J. Yoshio)
60958-3 is in development with new high definition capabilities and other additions, including a new compressed audio format for IEC61937.

61883-6, A/M protocol is being updated to add new ancilliary data for channel assignment; new ancillary data format for multi-channel PCM format

- Fujimori-san reported that 61883-6 Edition 2 was published in October last year. The 1394 TA is now preparing a further revision and will eventually wants to request the creation of an IEC maintenance team for 61883-6. Strawn asked whether AES could provide personnel for the maintenance team. M. Yonge suggested that the AES Liaison D relationship could be useful. Strawn will ask Yonge to follow up.

S. Harris suggested changing the title and scope for AES-X075. Strawn proposed instead to close this project and start a new project for IEC liaison.

AES-X101: Data Type, Properties, and Method Definitions for Audio Device Application Program Interfaces (API)
Secretariat to finalize format.

AES-X126: Profile for professional audio over 1394
SC-02-12-G has produced a draft on "32-bit generic data;" it is currently being secretariat-formatted as PWD. The current version is on the SC-02-12 document site as x126-generic-fjm-pwd-060119.pdf. No comments were received before the February deadline (nor since then). The meeting proposed to promote this draft to a Proposed Call for Comment document as soon as practicable.

AES-X132: Synchronisation of audio over IEEE 1394
Following circulation of the document x132-thaler-sync_pwd-060119.pdf ("Synchronization of Audio over 1394") in January, a number of comments were received, especially from C. Travis. Discussion clarified that the synchronisation was specifically for audio sampling frequency rather than for network-level transport. The scope of the draft was also clarified. The Secretariat will proceed to format this draft as PWD for a standard.

AES-X137: Liaison with 1394 Trade Association (1394 TA)
Fujimori-san reported on:

  • TA Audio Video Working Group work on AV/C
  • work conducted by ATSC DTV Task group
  • global real time synch
  • 1394 UI Task Group
Two documents have been accepted by the 1394 Board:
  • AVC Comamnd for AV Synchronization
  • AVC Panel Subunit 1.22
Additional drafts being prepared for TA Review:
  • ATSC DTV Task force (DTV guideline, tuner subunit, OSD guideline)

New Projects

Fujimori-san discussed the 1394 TA's new Pro Audio Working Group (PAWG). The PAWG have this charter:

Phase 1: Study Phase

The PAWG will form one or more application-related study groups to establish use cases for areas including recording, installed sound systems, and touring/live sound systems. Use cases shall be developed jointly with AES using the TA's existing Liaison relationship.
Phase 2: Evaluation and Recommendation Phase
The PAWG will recommend to the Board further development work to support the use cases from Phase 1, to be completed by the PAWG and/or other groups as appropriate. This could include specifications for the application of 1394 for pro audio use, and compliance procedures and requirements for ensuring interoperability of such applications.
Strawn reported that he worked with the 1394 TA to establish a specific AES liaison with PAWG. There is a clear common interest in developing use cases for various aspects of professional audio and these can be accommodated in combined task groups without prejudice to any future standards that may evolve from such work. Three new task groups will be established under SC-02-12 to facilitate the use case projects for Phase 1.
  • SC-02-12-H - Recording, leader F. Saelen
  • SC-02-12-J - Live Sound, leader S. Peer
  • SC-02-12-K - Audio Installations, leader R. Gurdan
Interested persons are encouraged to join these use-case task groups; an on-line signup form is available at:

R. Gurdan and Yonge discussed whether a Web forum could be used in addition to our normal e-mail reflector to facilitate the use case discussions. [Sec: this idea is supported under our rules and we have since set up such an arrangement.]

New Business

Reference to TA documents
We discussed the difficulty of AES Standards making normative reference to specifications published by closed groups like the 1394TA. To date, if reference to a document is necessary in a normative way to implement the AES standard, then the reference document must be equally stable and publicly available. In line with IEC Directives (see Section 6.2.2 of AES prefers to cite documents in this order of preference:
  • IEC/ISO international standards
  • international treaties published by ITU-R and ITU-T
  • industry-wide standards published by SMPTE, IEEE, AES, etc.
  • trade-association documents - difficult if not publicly available
It was clear that reference to 1394 TA documents would be useful, and may be necessary, to complete draft AES documents currently under consideration.

Strawn asked Yonge to investigate further.

Audio measurement use cases
B. Olson brought up the topic of audio test and measurement over 1394, which is not represented in the use-case groups proposed so far. Measurement of synchronization at the sample level with multiple boxes might be one topic. Acoustical measurements with 1394 as the platform might be another. How to guarantee sample-accuracy. Should the AES set up a fourth task group? Olson said he would be willing to lead such a group and feels that it should, if possible, be set up jointly with 1394 TA.

The next meeting will be held in conjunction with the AES 121st Convention, San Francisco, 2006-10.

AES - Audio Engineering Society