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 Warsaw, Poland, 2015-05-08
The meeting was convened by chair R. Foss.
The agenda and the report of previous meeting, held in New York, 2014-10-12, 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, a co-author of the original draft standard, has indicated that he will provide an update to the standard relating to more comprehensive grouping mechanisms, service discovery and block reading/writing. The secretary indicated that if only a small group is implementing a protocol that does not comply with the standard, then the group should consider withdrawing the standard to prevent it becoming an ‘orphan’ standard.
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: M. Yonge, who chaired the SC-02-12-M task group meeting, reported on the proceedings of the meeting. There are proposed revisions of AES67, some of these revisions being normative. Mark went through these normative and other revisions in the meeting. The working group should review these revisions, which are within an updated document on the working group document site. There is a two week comment period for the working group. If there are no comments, then the revisions are deemed to be accepted, and nothing further needs to be done.
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.
AES-R12 AES67 Interoperability PlugFest, Munich 2014
This is a published report containing an introduction, and conformance tests, including the test procedures from the Munich plugfest. No further action is required on this.
Development Projects
AES-X075: Liaison with IEC TC100 for IEC 61883
Project Scope: Prepare recommendations and assist the work of IEC TC100 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 that relate to the work of SC-02-12.
- The IEC 61883 series has no new issues now, but IEC 61883-8(BT.601 video) will be revised to carry metadata for camera applications.
- The IEC 60958 series will be revised or enhanced. A report was input to SC-02-02. It expands IEC 60958-3 to transmit multichannel, more bit length and metadata for the new audio systems such as 22.2 ch and others. Using IEC 60958 conformant data format, this revised IEC 60958 will be used by AVB and other transports to transmit audio data.
- In the IEC 61937 series, new proposals to transmit new MPEG-4 AAC, MPEG-H and AC-4 are being discussed.
AES-X170B: AES standards report – supplementary information on AES-64
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 draft is unchanged since 2011. This draft will be reviewed when the associated standard, AES64, is revised.
Given below are the four AES-X210 projects 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: The secretary indicated that work still needs to be done on the formatting of these documents. Foss reiterated the procedure to be followed after the formatting of the documents:
1. Allow for a reading time, say 2 weeks.
2. Plan a teleconference time and issue an invitation to the working group members to join.
3. Deal with any comments.
4. Move forward with publication.
Liaisons:
Liaison with Ethernet AVB: Foss indicated that there needs to be a liaison mechanism, and suggested contact with an active AVB member before a working group meeting to get an update on AVB activities. There was some discussion relating to Time Sensitive Networking (TSN) and its influence on AVB for audio, due to the increased availability of switches. J. Berryman discussed the OCA AVB adaptation layer for control of AVB devices. D. Zimmerman from Intel offered to be the liaison officer, and Foss indicated that he would confirm this after the meeting via email.
Liaison with MPEG: J. Grant did give some information on MMT (MPEG Media Transport). Their focus is on the receipt of media, so not very time constrained. Grant also mentioned low latency wide area transmission of audio over research networks, in particular the LOLA project. Transmission uses UDP. Apparently there was interest in AES67 by the members of the project. There was some related discussion about the regular nature or not of AES67 packet transmission. This has implications for the amount of buffer space on receivers.
Liaison with IEC 62379: P. Stevens indicated that there was not anything to report on.
New Projects:
Berryman commented a potential new project to identify a namespace standard and discovery service. He indicated that there is a lot of interest within the OCA alliance in this project. It might be that the OCA alliance prepares a draft for approval by the AES, similar to the approach followed in the X210 project . The current idea is that there will be an object model for the discovery service mechanism, and one or more protocols that are associated with the object model. Maximum use will be made of existing protocols. Jeff will be filling in a project proposal form for this project online. On the question of alignment with SMPTE, Jeff indicated that alignment might be possible with regard to the namespace standard.
New business:
There was no new business
The next meeting will be scheduled in conjunction with the AES 139th Convention, in New York in October 2015.
