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 139th Convention in New York, 2015-10-30.
The meeting was convened by chair R. Foss.
The agenda and the report of the previous meeting, 2014-05-08, were accepted as written.
Projects assigned to this group but not mentioned here had no action requested or required - see www.aes.org/standards/meetings/project-status.cfm for details.
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 two documents relating to updates to the specification had been placed on the document site. These have to do with a bulk storage and discovery mechanism and also grouping. The secretary requested that R. Gurdan, the originator of the documents contact the group with regard to updating the specification, and that there be a time frame for the update.
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: There is an updated standard, AES67-2015, and this review project will now be a review of this updated standard. K. Gross reported on an earlier meeting of the SC-02-12-M task group that generated the standard. There had been a short discussion of the plugfest to be held directly after the AES convention. There was interaction with SMPTE relating to their synchronization mechanism. There was a discussion about open technical issues relating to AES67 – issues relating to session initiation, performed by SIP. There was discussion about mechanisms for dealing with what happens when a receiver disappears.
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. There was a decision that this report should not be in the agenda in further meetings, but could be reactivated when someone has new input.
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.
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 provided the following liaison report:
1. IEC 61883-6. It was revised and published in 2014, no new proposals for revision are expected.
2. Related information. Consumer electronics amplifiers do not use IEEE 1394 any more, the main audio interfaces are now HDMI, SPDIF, and Ethernet.
IEC 60958 - also known as SPDIF - is a fundamental interface protocol, so IEC TC100/TA4 will enhance IEC 60958-1 and -3 to multi-channel use. This revised IEC 60958 will use the "IEC 60958 conformant data format" of IEC 61883-6. Stage 0 project of TA 4 started in September to study this issue, currently it is a call-for-proposals stage.
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.
Discussion: J. Berryman provided an overview of the three projects and their related documents.
Berryman indicated that there had been weekly conference calls that were open to SC-02-12 working group meetings and the documents were approved. Changes were incorporated into the documents and formatted by M. Yonge. Berryman pointed out that the class structure was open to enhancement with other features. The secretary indicated that these draft documents are now complete and that they will be elevated for comment to the subgroup above this working group. This can take up to 2 weeks. A public call for comment will then be issued which will be open for 6 weeks. If there are no comments that can’t be resolved after this period, the documents will be published. Yonge noted that document number AES70 (parts 1-3) had been assigned to the new standard.
[Secretariat note: these three draft documents were issued as a public Call for Comment on 2015-11-12. See above.]
AES-X226 AES67 protocol implementation
Project scope: This project was a placeholder for reports related to protocol implementation and conformance statements for AES67, in particular for successive plugfests. Yonge indicated that the plugfest to be held after the convention would also produce a report as a further output of this project.
Liaisons:
Liaison with Ethernet AVB: D. Zimmerman, the liaison officer, was not present. Foss discussed the proceedings of a workshop at the convention where the panellists described a number of AVB implementations, spoke about an open source AVB implementation, and described AVB layer 3 transport.
Liaison with MPEG: J. Grant provided information, which was included in the agenda and is repeated here for completeness:
“I'm not aware of anything that MPEG is doing currently that would be of interest to this group, though I haven't yet seen the output from their meeting last week in Geneva.
The work the mobile industry is beginning under the general heading of 5G may well be of interest, though it's currently at a very early stage. They are aiming at 1 ms latency for the air interface: there's some vagueness as to exactly what that means, e.g. whether one-way or round trip, but the intent is that it should be significantly less than LTE, and able to support tactile feedback, which is reckoned to need even lower latency than live audio. Anyway, they recognise that the network switches need to provide similar performance, and that that would be difficult with current technology. They also recognise other problems with IP, such as security and efficient use of bandwidth: it's been estimated that over half the bits carried on their networks are overheads such as packet headers. It'll become clearer during 2016 what the implications are for networked audio.”
Liaison with IEC 62379: P. Stevens indicated that two parts of the standard recently worked on, 3 and 7, relating to measurement and control of video streams, are now published IEC documents.
Liaison with SMPTE (SC-02-12-M task group): – the liaison document x226-151028-SMPTE to AES-Interop-2015-10-28.pdf is on document site. SMPTE's A. Lambshead had previously informed AES of interoperability testing of SMPTE PTP profile.
New Projects:
Namespace standard and discovery service
Berryman commented on this new project, which has the acronym ODA (Open Directory Architecture). Berryman had previously placed a draft project proposal on the document site.
Berryman indicated that there has been a lot of interest in this initiative recently and he had given a talk on ODA at the convention. Berryman also pointed out that it is critical to solve this problem soon, given the plethora of networking solutions. There is a need to create a project plan for the project. The project should preferably have a requirements analysis before embarking on the architecture. There is also a need to coordinate with groups that are currently working on the problem. In particular there should be cooperation with SMPTE. The OCA Alliance is supportive of the work and can commit funding to it.
Gross indicated that, from AES67 experience there wasn’t a suitable solution. There was agreement that a new project should be initiated that would determine the requirements for directory services. Berryman will make a proposal for this project.
New business:
The role of chair of the working group: Foss indicated that his involvement in application development meant that he was not in a position to keep abreast with the latest developments within the working group, and requested that anyone interested in taking over the role of working group chair should contact the chair of the AESSC, B. Olsen. Gross indicated that he would support anyone who took over the chair. Olsen expressed the need for leadership within the working group.
There was some discussion about IEEE 1588 version 3, the range of profiles currently in existence, and the issue of backward compatibility.
The next meeting will be scheduled in conjunction with the AES 140th Convention, in Paris in June 2016.
