SC-02-12 meeting, Berlin, 2014-04

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 Berlin, 2014-04-28.

The meeting was convened by chair R. Foss.

The agenda and the report of previous meeting, held in Rome, 2013-10-19, were approved as written.

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

Open Projects

AES58-R: Review of AES58-2008: AES standard for digital audio - Audio applications of networks - Application of IEC 61883-6 32-bit generic data
Project scope: to describe unique requirements for professional audio carried over 1394.

Discussion: Foss indicated that this related to the streaming of control data (apart from MIDI) over IEEE1394, and that the standard was complete. There was no further discussion relating to this standard.

AES64-R: Review of AES64-2012, AES standard for audio applications of networks - Command, control, and connection management for integrated media
Project scope: This standard specifies:
1. A set of structured Internet Protocol-based messages and a specification of the messages that can be used to control single or groups of parameters, and to monitor these parameters. The parameters are associated either with typical signal processing functionality within audio and other media devices, synchronization between such devices, or connections between such devices.
2. A definition of indexed parameters and a specification of the message format for such messages.
3. A definition of peer-to-peer grouping and master-to-slave grouping of device parameters, and a specification of the messages required to implement such grouping.
4. A definition of modifiers, and a specification of messages required to create and control such modifiers.
5. A definition of desk items as a means to extract graphical user information from a device and allow for the control of the device via the extracted graphical controls.
6. A definition of security levels, and a specification of messages required to set and get such levels.

Discussion: M. Yonge indicated that he would revise the standard with updates from Foss relating to global units. Foss indicated that additions to the standard relating to parameter snapshots and bulk parameter 'pushes' for monitoring purposes would be proposed as a future revision, these being based on current implementations.

AES67-R Review of AES67-2013 High-performance streaming audio-over-IP interoperability
Project Scope: This standard defines an interoperability mode for transport of high-performance audio over networks based on the Internet Protocol. For the purposes of the standard, high-performance audio refers to audio with full bandwidth and low noise. These requirements imply linear PCM coding with a sampling frequency of 44,1 kHz and higher and resolution of 16 bits and higher. High performance also implies a low-latency capability compatible with live sound applications. The standard considers latency performance of 10 milliseconds or less.

Discussion: K. Gross, leader of the task group that created the AES67 standard, commented on the proceedings of the SC-02-12-M meeting. In particular, he indicated that an AES67 'plugfest'would take place within the week 44 starting 2014-10-27. This will be hosted by the German broadcasting research centre, IRT, and coordinated by Sonja Langhans of IRT.

Gross also gave an update on the progress of a potential RFC related to the SDP signalling of reference clock sources, aimed at enhanced performance ( This work has been approved by the IETF and is in the editor queue for editorial review.

AES-R10: AES standards project report - Use cases for networks in professional audio
Project Scope: To identify and clarify use cases for networks in professional audio applications for Recording, Live sound, and Installations

Discussion: Gross agreed to upload the latest version of the use cases document to the working group document site.

Development Projects

AES-X075: Liaison with IEC TC100 for IEC 61883
Project Scope: Prepare recommendations and assist the work of IEC TC100SC-02-12 regarding the development and maintenance of relevant parts of IEC 61883. Any assigned task group shall report project progress to SC-02-12 and shall ask SC-02-12 for its advice on content. Administrative review of the project shall follow AESSC rules.

Discussion: J. Yoshio presented a liaison report that contained an IEC standards update and described work done on TC100 specifications related to SC-02-12.

1. IEC standard update

1.1 IEC 61883-6 (A/M Protocol) Edition 3.0 status - the final draft international standard (FDIS) has been edited and confirmed by the project leader. The FDIS will be circulated shortly. The revised items for edition 3.0 are - multichannel assignment, copy control information of DTCP+, and editorial corrections.

1.2 IEC 61883-8 (BT. 601) Edition 1.0 Amendment 1 status - this was published on 14 February 2014. The amended items are -- copy control information of DTCP+. The next revision is planned for bit length extension of video signal and metadata for car applications.

1.3 IEC 61883-1, 2, 3, 4, 5 and 7 status - part 2, 3, 4, and 5 were reviewed and their stability date extended. Part 1 and 7 will be reviewed.

AES-X137: Liaison with 1394 Trade Association (1394 TA)
Discussion: Foss agreed to contact M. Lave, the current liaison with the 1394TA and determine whether there would be further liaison information proceeding from the 1394TA.

AES-X170B: AES standards report - supplementary information on AES64
Project Scope: The objective of this information document is to present additional tutorial information pertaining to particular aspects of the AES64 specification, in particular:

1. The origins of the 7-level hierarchy
2. The creation and processing of AES64 messages
3. Peer to peer grouping and master/slave grouping of device parameters
4. Modifiers
5. Deskitems

Discussion: The report is unchanged since 2011. Foss and Yonge will communicate to establish whether it is ready for publication.

AES-X210A Open Control Architecture - Framework and object model
Project Scope: To specify a scalable control-protocol architecture for professional media networks. The initial version will address audio aspects only, but it is intended ultimately to expand the scope to video through collaboration with a video-oriented standards body such as SMPTE. Note that OCA is a control protocol only, and does not aspire to provide streaming media transport. It is intended to cooperate with all kinds of media transport architectures.

AES-X210B Open Control Architecture - Class tree
Project Scope: This document specifies control and monitoring classes to be used with the framework specified in AES-X210A.

AES-X210C Open Control Architecture - TCP/IP communications protocol
Project scope: This document specifies the protocol implementation for TCP/IP networks. This document refers both to general data types that are used in all transport protocols and to specific data types that are only used in the TCP/IP protocol.

[Secretariat note: The task group is actively considering exporting the comparatively simple UML object data model in the form of an XML Metadata Interchange (XMI) file to produce an electronic standard for the object data model that can be used directly by modeling programs and implementations without the need to transcribe printed text. Comments are invited from the working group]

AES-X210D Open Control Architecture - Minimum implementation
Project scope: This document specifies the minimum set of OCA objects, properties, methods, and events that a device must implement in order to be OCA compliant. The elements described in this document are not protocol-specific. Discussion: J. Berryman, the AES-X210 task group leader, provided feedback on the task group meeting held prior to the working group meeting. There is an intention to publish this part electronically as an XMI file to be a normative data model. The specification comprises a number of UML class diagrams, and many UML modelling tools are capable of XMI file storage and retrieval. There was some discussion regarding whether standards should be in machine readable form. There was also discussion regarding whether to publish the various components of the AES-X210 standard as a set together, or when each piece was ready. The consensus was to publish as an implementable set, although each would be reviewed by the working group when ready. All AES-X210 related work is to be completed by the next AES convention in Los Angeles.


Liaison with Ethernet AVB: M. Mora, who leads this liaison, was not present at the meeting. Berryman provided liaison information, highlighting areas where AVB was being deployed - mainly in the automotive field with some pro audio and some industrial take-up. A new AVB transmission scheme is being advanced to enable very high quality of service.

Liaison with MPEG: Nothing to report.

Liaison with IEC 62379: J. Grant briefly reviewed the various sections within IEC 62379, and indicated that the whole standard is due for review to enable broader appeal for implementers. In particular he indicated that 62379 is not wedded to SNMP, and that there is a potential solution to the complexity of SIP with regard to unicast messaging. He outlined a new approach to AV networking, indicating that since Ethernet AVB required changes to switches, it would be useful to more thoroughly analyse AV requirements and provide an optimal solution for AV traffic. This solution was presented as part of an AV networking workshop. He proposed that work be done within AESSC to promote such a solution.

New project

Name service and discovery. Berryman reiterated the importance of a name service that existed across subnets, required by both transport and control protocols. He presented slides that stated the problem in the form of a campus example, where multiple media research groups resided on various floors of a building and performed networking within a range of subnets. Each research group should have a secure identity in the form of a namespace, being able to communicate as a group. Berryman suggested that SC-02-12 design a namespace architecture and choose a small number of name service protocols on which to focus, for example Bonjour, and work out how the namespace architecture could be implemented with these protocols.

New business

There was no new business

The next meeting will be scheduled in conjunction with the AES 137th Convention, in Los Angeles in October 2014.

AES - Audio Engineering Society