SC-02-12 meeting, Los Angeles, 2014-10

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 conjunction with the AES 137th Convention in Los Angeles, 2014-10-12

The meeting was convened by chair R. Foss.

The agenda and the report of previous meeting, held in Berlin, 2014-04-28, were accepted as written.

Open Projects

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: Foss indicated that work is being done within the company UMAN to enhance the capability of the standard. R. Gurdan, co-author of the standard has indicated that he will provide an update to the standard relating to more comprehensive grouping mechanisms, service discovery and block reading/writing.

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: No further work has been done on the report. The report will remain as a published report on the working group document site.

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. He indicated that there were four issues to be dealt with in the current draft and that a review of the current draft would be performed after the plugfest.

Development Projects

AES-X075: Liaison with IEC TC100 for IEC 61883
J. Yoshio presented a liaison report that contained an IEC standards update and described work done on TC100 specifications related to SC-02-12. Regarding the IEC 61883 series of standards:

IEC 61883-6 ed3.0 (2014-09): Consumer audio/video equipment - Digital interface - Part 6: Audio and music data transmission protocol This is now published, and the revised items include: Up to 34-channel assignment with IEC 62574 (definition of channel assignment); DTCP+ is now supported. It may be that there will be no further revisions in the future.

IEC 61883-1,2,3,4,5,7 : - These are all stabilized and will be reviewed in 2016/2017.

IEC 61883-8: Part 8: Transmission of ITU-R BT.601 style digital video data. A Document for Comment (DC) is expected to be submitted to start revision work. Metadata will be added for automobile camera monitoring applications. The specification for video signal length will be expanded

AES-X137: Liaison with 1394 Trade Association (1394 TA)
Project Scope: Liaison with 1394 Trade Association (1394 TA) Discussion: Gross indicated that the 1394TA is no longer active, but that all the documents are publicly available. M. Lave, who was previously our liaison with the 1394TA confirmed this and indicated that there is no further need for a liaison.

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. M. Yonge will read the report to determine whether editing changes are necessary. Foss and Yonge will communicate in this regard.

Given below are the four parts of the AES-X210 project with their scopes, followed by a report on the discussion related to these.

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 SC-02-12
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.

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. Regarding AES-X210A, there were minor revisions to be performed. Regarding AES-X210B, there was agreement that the class tree be published electronically in XMI format. AES-X210C needs to be written in standards-compliant language. Berryman will do this and check editorial content with the secretariat.

The intention is to include the content of AES-X210D an appendix of AES-X210B. Yonge accordingly proposed that the AES-X210D project be retired as a separate task.

The goal is get drafts for parts A, B, and C to the working group by mid November. The working group will require 2 months to analyze and comment, and it should then be possible to publish the standard in February 2015.

AES-X226 AES67 protocol implementation
Project scope: This project aims to develop a protocol implementation and conformance statement for AES67

K. Gross indicated that a list of conformance items have been produced, and these will aid manufacturers in their preparation for the plugfest to be in Munich at the end of October. Yonge indicated that the plugfest will produce an output in the form of a report, and this will be handled within project AES-X226. The conformance tests could be published as a table. Suggested test procedures could also be published. It was suggested that the table of conformance tests be published as a report.


Liaison with Ethernet AVB: M. Mora, who leads this liaison, was not present at the meeting. Berryman provided some AVB-related information, indicating work that is being done on layer 3 transport and the possibility of alignment with AES67. Gross indicated that the AVB certification procedure was now complete.

Liaison with MPEG: Nothing to report.

Liaison with IEC 62379: P. Stevens emailed a liaison report as follows:
Earlier this year IEC 62379-3 Ed. 1.0 Common Control Interface for networked digital audio and video products - Part 3: Video (TA 4) had gone through the CDV (Committee Draft for Vote) stage and as a result a liaison statement was received from ISO/IEC JTC1/SC29/WG11 (Coding of moving pictures and audio) to IEC TC 100 suggesting the adding of the HEVC standard (ISO/IEC 23008-2, twin text with ITU-T Rec. H.265) to the coding type sub-identifier in our tree. This has been duly added and the document is now back with the IEC secretariat for final checking, editing and approval before proceeding to Final Draft International Standard (FDIS).

The International Standard IEC 62379-7 Ed. 1.0 Common Control Interface for networked digital audio and video products - Part 7: Measurements (TA 4) has been approved for publication - expected February 2015. This is the document resulting from the work done within the EBU IP Measurements Group (now closed).

J. Grant indicated that not much has happened since Berlin regarding other parts.

New project

Network name service: Berryman discussed the need for a name space standard, required by both transport and control protocols. He believes that it is not practical to simply use domain names for media networks. A layer-7 name is required. Directory engines are needed to store the names. The fundamental problem is to obtain addresses from names. Not all directories can be used for discovery and not all are automatically updated. SMPTE and IETF (Bonjour update) are looking into aspects of the problem.

Berryman's proposal is that a namespace standard be created first and a directory mechanism second, using current practise as much as possible. Gross indicated that a discovery service had been investigated in AES-X192 and no solution found, which might lead to something new needing to be created. There was a proposal that the group look at the SMPTE Media Device Control document. Yonge agreed to obtain permission from SMPTE for the group to view the document.

Lave indicated the need to educate people regarding he problem. Berryman presented a set of slides of a campus network with a requirement for multiple groups each having their own media network, where these media networks might be on multiple, possibly overlapping subnets. Each media network has its own namespace. It became apparent that it was necessary to define requirements and Yonge indicated that an exploratory project could be initiated. Berryman agreed to provide a project proposal that would, in particular, define the scope of the project.

New business

There was no new business

The next meeting will be scheduled in conjunction with the AES 138th Convention in Warsaw, Poland, in May 2015.

AES - Audio Engineering Society