Report of the meeting of the SC-02-01 Working Group on Digital audio measurement techniques, held online, 2020-10-06.
The meeting was convened by chair J. Datta.
The report of the previous meeting, held online 2020-05-26, was approved as written.
The agenda was approved as written.
In attendence were Chris Lacinak, David Andrews, David Prince, Fred Morgenstern, John Grant, Paul Treleaven, Rich Cabot, Swen Mueller, and Tomlinson Holman
AES17-R Review of AES17-2015: AES standard method for digital audio equipment - Measurement of digital audio equipment
Status: The group discussed the practice in the industry where a full-scale sine wave is sometimes referred to as 0 dBFS by some but as -3 dBFS by others. This causes confusion. Rich C will add another note under “Decibels full scale” to clarify further and circulate within this group.
It is noted, that while this document is pretty clear, the problem probably lies in the fact that few people read through the standards.
AES-12id AES Information Document for digital audio measurements - Jitter performance specifications
Status: Review for elimination of insensitive terms
The following proposal was accepted:
4 Jitter transfer
A clean-and-simple clocking arrangement might have a free-running crystal oscillator connected directly to local ADC and DAC chips. But such arrangements are not very common. Even in DVD players for example, the audio clocks come via a PLL (phase-locked loop), locked to 27 MHz. And in digitally connected systems, downstream devices commonly sync their audio clocks either to an incoming audio stream or to a nominated sync reference. Every stage in the clocking chain can potentially contribute jitter to the derived audio clocks.
AES-X217 Audio ADC test method and performance specification for archiving and preservation applications
Status: Chairman to set up session of the task group consists of Rich Cabot, Ian Dennis, Chris Lacinak, to discuss outstanding items and then seek input from SC-03-06.
Goal target: 2021-05
Liaisons
No new liaison information.
New projects
No new projects were proposed.
New business
Informational: ADCTest is a desktop application (that borrows from X-217) – new version will be released shortly. More information available at:
https://www.weareavp.com/products/adctest/
https://github.com/LibraryOfCongress/ADCTest
The next meeting will be scheduled in conjunction with the AES 150th Convention, to be held either face-to-face or online in May 2020.
