Report of the meeting of the SC-02-01 Working Group on Digital Audio Measurement Techniques of the SC-02 Subcommittee on Digital Audio, held in Vienna, Austria, on 2007-05-06

The meeting was convened by chair S. Harris.

The agenda and the report of the previous meeting held on 2006-10-06 was approved as written.

Open Projects

AES-R7, Accurate peak metering
This project is now complete and should be retired.

AES-6id-R Personal Computer audio quality measurements
A substantial revision of tthis information document was published 2007-02-21. No action required at this time.

AES-12id Jitter Performance Specifications
This information document was published 2007-03-19.

A complaint was subsequently received about including a proprietary part number in one of the figures. The part number was not necessary for the use of the document and will be removed as an editorial matter. The document will be reprinted again within a short time.

AES17-R Measurement of digital audio equipment
T. Kite has not sent his PTD yet. I. Dennis agreed to contact Kite and discover the status of this work.

R.A. Belcher described his method of measuring crosstalk between channels in a multi-channel converter that uses active signals on each channel, rather than having a big signal on one channel, and zero signal on the other channels. Pseudo-Random Binary Sequence (PRBS) generators were used. A presentation about this idea will be posted to this group's document site.

There is a new IEC standard that described measuring A/D converters. This is IEC 60748-4-3, "Dynamic Characterisation of Analog to Digital Converters", published 2006-10. This standard includes the above PRBS idea.

This idea belongs more in AES17 than in AES-6id since this is a generic measurement technique and not unique to personal computers.

Dennis suggested that this idea can be included in the current revision cycle of AES17 in two places: A simple active signal crosstalk test using sine wave tests, which would belong in the main body of AES17. The more complex version, using multi-tone tests, can be included in the new annex, which describes more complex multi-tone tests. Dennis will work with Belcher to include these active signal crosstalk tests in the next revision of the AES17.

There was some discussion about the need for a discussion forum or similar for proposing new measurement techniques without going through the full standards review process.

AES-X102 Liaison with IEC MT61606
A new version of IEC 61606 is waiting to enter the Committee Document for Vote (CDV) stage. Working Draft version 7 was distributed in 2007-03. Discussion will take place at the IEC MT61606 meeting which will happen immediately after this SC-02-01 meeting. The CDV is due in 2007-05 (that is, within the next 4 weeks).

We discussed how to freeze the AES inputs into the IEC document. Perhaps in the future we should create a separate project specifically for making a contribution document, with a clear end date.

AES-X118 ITU-R study group 6 liaison
The loudness unit designator discussion is decided and now losed.

There is an ongoing discussion about time constants.

The ITU group met earlier this week, and we would be grateful to receive a report soon on the outcome of that meeting.

Liaisons

ITU WP6Q has a revision plan for PEAK meaurement. Yonge will look into a liaison with this group.

New business

Lip sync errors.
A. Mason is doing some work on HDTV lip sync guidelines within the European High Definition forum.

Mason is measureing lip sync sensitivity for Standards Definition (SD) versus High Definition (HD) television pictures. Subjects were asked to correct a deliberately introduced lip-sync error for HDTV and for SDTV. Some early results were presented, but only for a very small sample size.

The next meeting of SC-02-01 will be at AES 123rd Convention in New York on October 2007.