Report of the SC-02-02 Working Group (WG) on Digital Input/Output Interfacing of the SC-02 Subcommittee on Digital Audio meeting, held in conjunction with the AES 114th Convention in Amsterdam, Netherlands on 20th March 2003

J. Grant, Vice-Chair of SC-02-02, convened the meeting.

M. Yonge, AESSC Secretary, reminded the attendees of the recent untimely death of J. Dunn, Chair of SC-02-02. It was noted by all present the tireless and outstanding work over many years that Julian did for the AES and the Working Group.

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

Open Projects

AES-2id-R Review AES-2id-1984: AES information document for digital audio engineering -- Guidelines for the use of the AES3 interface

After reviewing the situation since the previous meeting of the working group R. Caine proposed, primarily due to time considerations, to delete the sections labeled "under consideration" and to discontinue activity on AES-X50. This was accepted without disagreement by the attendees.

AES-3id -R Review of AES-3id-2001 - AES information document for digital audio engineering -- Transmission of AES3 formatted data by unbalanced coaxial cable

No action was taken.

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

No action was taken.

AES-10id-R Review of AES-10id - Engineering guidelines for the multichannel audio digital interface (MADI) AES10

This document will be reviewed following completion of AES10-R.

AES3-R Revision of AES3-1992 (r1997): AES Recommended Practice for Digital Audio Engineering --Serial transmission format for two-channel linearly represented digital audio data

J. Brown presented data on various cable characteristics. A discussion amongst the members followed including the recognition that it was important to keep continuity of such characteristics at all times between the transmitter and receiver to achieve best or even proper operation (ex. continuity in the shield was of particular importance).

Yonge and Caine are requested to examine the present PWD and update as needed (such as conforming with the IEC version as appropriate) with a target for circulation to the WG by beginning of May.

AES10-R Review of AES10-1991 (r1997): AES Recommended Practice for Digital Audio Engineering -- Serial multichannel audio digital interface (MADI)

All present comments have been resolved.

AES18-R Review of AES18-1996: AES Recommended Practice for Digital Audio Engineering -- Format for the user data channel of the AES digital audio interface

No action was taken.

AES41-R Review of AES41-2000 -- AES Recommended Practice for Digital Audio Engineering -- Recoding data set for audio bit-rate reduction

No action was taken.

AES47-R Review of AES47-2002: - Digital Audio in asynchronous transfer mode (ATM)

Yonge and Grant to prepare a draft document for possible action by SC-02 with respect to allocating funds for maintaining a registry of "IDs" (note, this might be a recurring cost).

AES-X50 Guidelines for Development of Specifications Which Reference or Use AES3 Formatted Data.

The WG decided to recommend to SC-02 to discontinue the project (project has been inactive for a long time and much of the work is being done under AES-2id-R).

AES-X111 Transmission of the unique material identifier (UMID) on AES3. This project is the subject of a Task Group SC-02-02-G meeting, chaired by C. Chambers, and scheduled for tomorrow.

AES-X119 Connector for AES3 interfaces

Brown reported that the Task Group (SC-02-02-F) feels that the removable key approach previously discussed is not practical for various reasons (ex. cost, and fool-proof operation), but a mechanical approach that is not removable still has much merit. In order to show feasibility the Task Group developed an example, distributed at the meeting of the WG, of such an approach that would be adaptable to present installations with minimal disruption depending on the situation. But specifics of a final design are left to the connector manufacturers to finalize. Further, the Task Group recommends to SC-02-02 that equipment designed for: a) only analog connection use a particular connector for that purpose; b) only digital connection use a particular connector for that purpose; and c) compatible connections be made available for those who need to accommodate both analog and digital. This appears to be substantially the same basic strategy that the Task Group had reported on before (see minutes from LA meeting of the WG), but with a different example of a physical approach to the solution of the connector.

The WG members present at the meeting felt that there is benefit to having a compatible connector for digital use and interoperable with that already adopted in AES3 (i.e. XLR). But there are still important issues that need to be resolved. The WG requested that the Task Group prepare a survey, i.e. questionnaire, to interested parties including equipment manufacturers and users to respond to the recommendations in the TG report (amended with the new approach to the physical connector as mentioned above). Prior to general circulation the draft should be posted to the reflector for comment by the WG.

PIR: Liaison with EBU P/AGA

A formal liaison project has been proposed to augment the contact between AES Standards and EBU Technical Group P/AGA - the Advisory Group on Audio.

Liaisons

Mr. Yoshio mentioned that there will be a meeting of the IEC60958-1 maintenance team this week. Among the issues to be discussed are Category Codes for hard disc recorders.

Mr. Yoshio also mentioned that DVD Forum WG-10 on professional recording applications of DVD has started a new work item on audio.

New Projects

There were no new projects.

New Business

There was no new business.

The next meeting is scheduled in conjunction with the AES 115th Convention in NYC, USA, October 2003.