SC-02-01 meeting, Amsterdam, 2008-05

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 Amsterdam, Netherlands, 2008-05-18

The meeting was convened by chair S. Harris.

The agenda and the report of the previous meeting held on 2007-10-06 were approved as written.

Open Projects

AES-R7: Standards project report - Considerations for accurate peak metering of digital audio signals
The report has been published and it was proposed to close this project.

AES-6id-R Review of AES-6id-2006: AES information document for digital audio - Personal computer audio quality measurements
No action requested or required.

AES-12id-R Review of AES-12id-2006: AES information document for digital audio measurements - Jitter performance specifications
Should we update AES-12id because of recent discussions about jitter in AES3? Harris will send an e-mail to SC-02-02 to remind that group about the existence of AES-12id, and recommend that they read it.

It was also proposed to add a reference to AES3 in AES-12id. This can be done as an editorial matter; M. Yonge will suggest a suitable change to the Overview to add a reference to both AES3 and AES-2id for information about interface jitter.

AES17-R: Review of AES17-1998 (r2004): AES standard method for digital audio equipment - Measurement of digital audio equipment
Not much progress has been made on our revision. Most work has been focussed on contributing to the IEC 61603-6 document. [For the status of this document, see below]

There was a general discussion about whether to develop AES17, or to retire AES17 and simply contribute to IEC 61606-3 maintenance.

It was noted that some contractors, particularly for big building contracts, prefer to use IEC standards because of their formal international status. Other projects prefer to reference AES standards.

M. Furukawa commented that there were many examples of bodies that submit standards to IEC, but they do not stop development of their own. For example 1394TA submitting docs to IEC 61883.

I. Dennis, the primary author of IEC 61606-3, does not want to duplicate update work. In this case, the timing of the revision of IEC 61606-3 was such that it had to be updated first. There was a discussion about keeping AES17 closely aligned with IEC 61606-3 while retaining the flexibility to add topics to the AES standard.

R. Chalmers, AESSC Chair, expressed the view that we should continue to develop AES17 because measurements of professional audio equipment were of fundamental importance to the Society and new techniques continued to be developed. The meeting agreed with this view. The secretary will check with IEC about our freedom to use text and drawings from IEC 61606-3, so we can adopt elements of IEC 61606-3 for AES17.

Dennis had indicated to Harris that he may have some time available later in the year to help contribute to AES17 revision. T. Kite also indicated that he may have some time available to help with revision of AES17. Harris offered to speak to relevant manufacturers in the AES exhibition to see if they wanted to contribute to revising AES17.

Anyone wishing to contribute to the revision of AES17, should send an e-mail to sc-02-01@standards.aes.org indicating their willingness to contribute.

Development Projects

AES-X102: Liaison with IEC TC100 PT 61606
The status of IEC 61606-3, Audio and audiovisual equipment - Digital audio parts - Basic measurements methods of audio characteristics - Part 3: Professional use, was reviewed.

The Committee Draft for Vote (CDV) was recently approved with no negative votes, although a number of minor editorial comments were made by IEC central office. A Final Draft International Standard (FDIS) will be circulated in 2008-06 and an International Standard (IS) is expected to be published in 2008-08.

AES-X118: ITU-R study group 6 liaison
No comments were received. ITU-R study group 6 is continuing to discuss the loudness issue. AES had decided not to be involved in the subjective testing aspects of this.

E. Skovenborg wanted to continue and wake up the liaison. The wording of ITU document is focussing on dialogue level, but there may not be any dialogue in - for example - a music recording.

An information document is needed to educate people about various aspects of loudness measurement. A. Mason will send a note to the SC-02-01 e-mail reflector to start a discussion.

AES-X177 Audio Video synchronisation
Mason has written a document, "Factors Affecting Perception of audio-video synchronisation in Television", which is now available on the SC-02-01 document site. He encourages interested members to read this doc.

The first part is about the human perception of lip sync. It appears that the apparent distance of a visual image affects sound timing expectations. It is also clear that the choice of display technology affects when you measure the video presentation time.

A video clapper board can be used to establish a simultaneous timing reference in video and audio. Mason has also developed a small piece of equipment which measures the timing of a video "flash". This work will be presented as an AES paper in San Francisco in October.

The ultimate goal is to draft a standard. If anyone has comments on the document, please send a note to the SC-02-01 e-mail reflector.

Liaisons

There were no additional liaison matters.

New Projects

No new projects were proposed.

New Business

There was no new business.

The next meeting will be scheduled in conjunction with AES 125th convention in San Francisco, CA., US., 2008-10.

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