Meeting of SC-02-01, Barcelona, 2005-05

Report of the meeting of Working group SC-02-01 on Digital Audio Measurement of the SC-02 Subcommittee on Digital Audio, held in Barcelona, Spain,, 2005-05-29.

The meeting was convened by chair S. Harris.

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

Open projects:

AES-6id Personal computer audio quality measurements
The meeting felt that the PTD should be progressed to a PWD. A number of drawings need to be completed in their final format. M. Yonge will work with W. Jones on this.

AES17-R Measurement of digital audio equipment
I. Dennis has posted a document which discusses potential revisions to AES17-1998. He discussed some of the issues mentioned in the document.

  1. Discussion of the definition of "full scale", particularly in cases where the analog signal clips before digital full scale has been reached. It was proposed to use digital FS, except for a box that has only analog i/o (no digital i/o). In that case, a distortion level should be specified.
  2. Jitter susceptibility. There was a discussion about making the specified filter more narrow so that more jitter components would be included in the measurement. The Fs/192 stimulus variant seems to be poorly understood.
  3. Noise measurements. What type of weighting should be used. An informative note about the benefits of each weighting filter type should be included.
  4. THD+N. It was proposed to stay with -1 dBFS for signal level.
  5. A task/writing group was set up to progress this work. Initial names are: I. Dennis, C. Travis, R. Caine, and M. Keyhl who commented that he would like to add or refer to perceptual coding methods.
Harris will send email to the group to request participation in the AES17 revision process.

AES-X102 Liaison with IEC PT 61606
A working draft of 61606-4, professional audio measurements, was presented at the previous IEC meeting. The next meeting is scheduled for later today, please attend if you are interested.

AES-X118 ITU-R study group 6 liaison
There has been some activity on reflector. Keyhl is not sure of the current status. Just monitoring activity today.

AES-X151 Jitter performance specification
An AES-formatted PTD of this Information Document has been posted. It is intended to propose this as a PWD by end of August. Travis will post an updated version. The target is to propose this document as a PCFC before the next meeting.

The chair thanked Travis and Wolfson for their contribution.

AES-X141 Accurate measurement and indication of peak signal levels to avoid overload of digital media.
The ITU meeting in October 2004 was cancelled. Keyhl felt that more detailed parameters for the measurement need to be defined.

The meeting was reminded that C. Todd's comment from the previous meeting, we should focus on measure peak value in the current stream and not to try to predict the behaviour of downstream devices.

Dennis will send some references about upsampling rate ratio affect on measurement accuracy, with help from Travis.

An updated report is needed before the next ITU meeting in September 2005. Keyhl will make this happen, with help from T. Holm Hansen.

Liaisons

There were no other liasons

New projects

There were no new projects

New business

There was no new business

The next meeting will be scheduled in conjunction with the AES 119th Convention to be held in New York, 2005-10.

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AES - Audio Engineering Society