SC-02-02 meeting, Online, 2022-10

Report of the meeting of the SC-02-02 Working Group on Digital audio interfaces, held online, 2022-10-14.

The meeting was convened by chair John Grant.

Present were Richard Cabot, Paul Treleaven, John Grant, Al Walker, Junichi Yoshio, Jim Meyer, Hatano Wataru, Stephen Scott, Anthony Kuzub, Kevin Gross

The formal notice on patent policy was read.

The agenda was approved as written.

There were no comments on the report of the previous meeting, held online, 2022-05-06.

Projects assigned to this group but not mentioned here had no action requested or required - see for details.

Open projects:

AES10-R Review of AES10-2020: AES Recommended Practice for Digital Audio Engineering -- Serial Multichannel Audio Digital Interface (MADI)

Following discussion at the previous meeting and subsequently on the reflector regarding implementation over twisted pair (MoTP), J Meyer had produced a report which was circulated on 29th August and is also in the SC-02-02-L task group document repository.

Four systems for sending multichannel audio over twisted pair have been identified in the marketplace (not including networked audio, such as AES67, which can of course also be used over twisted pair cabling):

(1) AES50
(2) AES-X215, which uses 100 Mb/s Ethernet physical layer and thus uses a different encoding on the cable than AES10 and also requires a bigger gap between frames than MADI provides when carrying 64 channels at 48 kHz
(3) same coding as AES10, using the same transformer isolation as Ethernet
(4) same coding as AES10, directly connected (no isolation) over shielded cables with ferrites for interference suppression

There are two options:
(a) resurrect X215 and extend it to include (3) and (4) above, or
(b) start a new project to write a report (or a new section in AES-10id) detailing all four options and recommending best practice.

In either case a volunteer would be needed to edit the document.

Other projects:

No activity.


J Yoshio reported that a new Part (part 16) is proposed for IEC 61937 (non-linear PCM encoded audio bitstreams over IEC 60958; the "professional" version of IEC 60958 is the same as AES3) to support the AVSA format. All the data type code points (Table 2 in Part 2) have been used so it will need to use an "extended" data type.

New projects

No new projects were proposed.

New business

No new business was raised.

The next meeting will be held online in May 2023, scheduled in conjunction with the AES 154th Convention.

AES - Audio Engineering Society