SC-02-12 meeting report, Amsterdam, 2008-05

Report of the meeting of the SC-02-12 Working Group on Audio Applications of Networks of the SC-02 Subcommittee on Digital Audio, held in Amsterdam, 2008-05-19

The meeting was convened by chair R. Foss.

Suggestions for amendments to the published agenda, previously circulated on the reflector by Foss, were agreed upon by the participants.

The report of the previous meeting, held in New York, 2007-10-07, was accepted as written.

Development projects

AES-X075: IEC TC100 Liaison for IEC 61883
IEC 61883 is a multi-part standard formalising IEEE 1394 IEEE Standard for a High Performance Serial Bus, also known as "Firewire".

J. Yoshio reported for IEC:

  • IEC 61883-1 - Consumer audio/video equipment - Digital interface - Part 1: General; this revision is at the Committee Draft for Voting (CDV) stage.
  • IEC 61883-8 - Consumer audio/video equipment - Digital interface - Part 8: Transmission of ITU-R BT.601 style Digital Video Data ; is also at the CDV stage.
  • IEC 61883-6 - Consumer audio/video equipment - Digital interface - Part 6: Audio and music data transmission protocol. After the A/M protocol is revised in 1394TA, it will be proposed to IEC to revise IEC 61883-6.
Further information on the 1394TA work on the A/M protocol will be provided in the 1394TA liaison report [see below].

AES-X101: Data Type, Properties, and Method Definitions for Audio Device Application Program Interfaces (API)
Project scope: Define and publish recommended data types, properties, and methods for use in the control of common audio devices.

Foss indicated that there was useful information in this report. K. Gross had requested the original drafts via the reflector. M. Yonge said that work was needed with regard to formatting the report according to AES guidelines. K. Dalbjorn said that if the report was found to be useful, he would be willing to do some work on it. It has been modified substantially from the original. Foss agreed to coordinate an effort to create a document that would follow AES guidelines.

AES-X126A : Profile for professional audio over 1394; "Application of IEC 61883-6 32-bit Generic Data"
Project scope: to describe unique requirements for professional audio carried over 1394.

The Secretariat-formatted PWD will be promoted to PCFC as soon as possible.

AES-X132: Synchronisation of audio over IEEE 1394
Project scope: to specify methods of audio clocking and sampling-frequency synchronisation in a professional audio network based on the IEEE 1394 high performance serial bus. Include techniques to ensure devices function correctly in a network which includes IEEE 1394.1-compliant bridges.

This was confirmed to be a useful document. Waiting on the secretariat to be formatted as a working group document.

AES-X137: Liaison with 1394 Trade Association (1394 TA)
J. Yoshio reported that he was not able to make the last Quarter-2 1394 TA meeting in Shenzen, China. However, he has made available minutes of that meeting, which are posted to the document site. He indicated that work is still underway on channel assignment within the 1394 TA A/M protocol and, once completed, these recommendations will be proposed for incorporation into IEC 61883-6. He indicated that work had been done on string formats within AV/C by A. Yanowitz. Work is also being done on Digital Transmission Content Protection (DTCP) testing. Lastly there has been work done on set-top-box testing. There was no information regarding changes to the Music Subunit.

Yoshio has uploaded two files to the working-group document site:

  • X137-9-Apr-08-AVWG-Minutes.pdf
  • X137-AM_Protocol_2Q2008.pdf

AES-X156 "Use cases for networks in professional audio"
Project scope: to identify and clarify use cases for networks in professional audio applications.

The three documents produced from the task groups of the three use-case projects - AES-X156, AES-X157, and AES-X158 - were merged and formatted by the secretariat to produce a single document (PTD) that was open for review by members of this working group. The secretariat had certain questions regarding the document, and these questions have now been answered by Foss and R. Gurdan. The secretariat will produce a further version of the document.

AES-X170: "Integrated Connection Management and Command and Control Protocol"
This was a project introduced in the working group meeting in Vienna, 2007-05. Gurdan provided an overview of the XFN protocol that forms the basis of the project proposal. Gurdan agreed to make this presentation available on the document site. After the presentation J. Grant asked about the areas in which there were patents. Yonge confirmed the need for patent information and conformity with the AES rules regarding patents. Foss and Gurdan agreed to provide this information.

Grant indicated that there were areas of overlap with IEC 62379. Foss and Grant agreed to work together and document areas of overlap. Foss agreed to provide complete documentation of XFN in order to enable this.


Report from SC-02-12-G Task Group meeting
Gurdan, the task-group leader, reported that the initial focus of the group was to be within the areas of installation and live sound. S. Harris had provided information about the current protocol usage within the consumer space, and particularly indicated the momentum that UPnP ("Universal plug and play") has gained within this space.

There was some discussion about the Advanced Control Network (ACN), and Gurdan indicated the problems that he felt might be encountered using ACN in a professional audio context. Dalbjorn believed that it would be useful to look at ACN, and indicated how to access ACN documents.

Liaison with Ethernet AVB
M. Mora, in charge of this liaison, was not able to attend the WG meeting. Foss listed the various groups concerned with Ethernet AVB development:

  • 802.1AS provides timing synchronization across the network.
  • 802.1Qat is used to guarantee bandwidth for QoS through the bridges.
  • 802.1Qav specifies the forwarding and queuing rules to enforce the bandwidth reservations.
  • 802.1BA will be the document that describes how to use the three previously mentioned standards to create an AVB network.
  • P1722 is a layer 2 protocol (looks a lot like 1394 encapsulation) for audio/video transmission across the network.
  • P1733 is a layer 3 protocol (RTP based) for audio/video transmission across the network.
There was consensus that we needed to have a formal liaison with the Ethernet AVB groups and if possible have their documents accessible on our document site. We decided that Mora would be the right person, with the secretary, to set up this liaison.

There was some discussion, particularly from U. Zanghieri and Dalbjorn, regarding the current state of Ethernet AVB implementation, with indications that there were reference designs for chips, and plans to incorporate Ethernet AVB capabilities into switches.

It was proposed to create a new project and associated task group related to Ethernet AVB, with the goal of producing an information document on the professional use of Ethernet AVB. Foss agreed to create a project proposal for this. M. Page and P. Foulkes indicated their willingness to be part of this task group.

New projects

New business

There was no new business

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

[includes editorial correction, 2008-06-23]

AES - Audio Engineering Society