SC-02-08 meeting, Amsterdam, 2008-05

Report of the meeting of the SC-02-08 Working Group on Audio-File Transfer and Exchange of the SC-02 Subcommittee on Digital Audio, held in Amsterdam, 2008-05-17

The meeting was convened by chair M. Yonge.

The agenda and the report of the previous meeting, held on 2007-10-05 in New York, were accepted as written.

Open projects

AES31-1-R: Review of AES31-1-2001 (r2006): AES standard for network and file transfer of audio - Audio-file transfer and exchange - Part 1: Disk format
No action was requested or required

AES31-2-R: Review of AES31-2-2006: Audio-file transfer and exchange - Part 2: File Format for Transferring Digital Audio Data Between Systems of Different Type and Manufacture
Project scope: This standard defines a file format for interchanging audio data between compliant equipment. It is primarily intended for audio applications in professional recording, production, post production, and archiving.

It is proposed to add informative notes regarding null-terminated strings and null-filled fields at next opportunity. An amendment for large file sizes is in preparation - see AES-X162, below

AES31-3-R: Review of AES31-3-2008, AES standard for network and file transfer of audio - Audio-file transfer and exchange - Part 3: Simple project interchange. including maintenance of annex F.
Project scope: This standard provides a convention for expressing edit data in text form in a manner that enables simple and accurate computer parsing while retaining human readability. It also describes a method for expressing time-code information in character notation. It supports common professional audio sampling frequencies, video frame rates, and film framing. This document addresses the core need of the AES31 series of standards in providing a simple but extensible system for passing audio material between systems.

The revised standard, AES31-3-2008, was published 2008-05-08.

There was no discussion of the content of the newly revised standard, but there was some discussion of the XML-coded version developed by David Ackerman that generated significant interest.

AES46-R: Review of AES46-2002 (r2007): AES standard for network and file transfer of audio - Audio-file transfer and exchange - Radio traffic audio delivery extension to the broadcast-wave-file format
Project scope: This document provides a means for communicating basic radio traffic and continuity data via a dedicated chunk embedded in broadcast-wave-compliant WAVE files. The new RIFF chunk supports most common data used in radio traffic and continuity systems, while the WAVE format itself supports most sampling frequencies, sample widths, and audio formats.

No action was requested or required

Development Projects

AES-X149: Format and Recommended Usage of the Direct Stream Digital Interchange File Format (DSDIFF)
Project scope: To standardise a file format to allow general interchange of sound files based on DSD-coded data based on an existing specification. The DSDIFF file format is intended for storage and transfer of DSD and DST (encoded DSD) material.

Current goal: Formatted PWD, Goal date: 2008-07
Secretariat formatting awaited

AES-X162: Amendment to AES31-2, File-size extension
Project scope: Adopt the file-size extension technique from EBU T3306 as an optional amendment to AES31-2 BWF.

Intent: Amendment to standard, Target: 2008
Current goal: PWD, Goal date: 2008-07
Status: Revised PWD pending

The meeting discussed the draft in some detail, with some proposals:

The purpose of the 'JUNK' chunk should be clarified.
The wording defining the 'ChunkSize64' should be corrected to clarify its use to store future 64-bit variables, and to correct a numerical error.
In order to clarify the file structure, R. Caine suggested that the chunk structure could be shown more simply in the form of an indented list in addition to,or instead of, the figures currently used. The table in G.4.1 should highlight the 'JUNK' chunk while retaining the context of other data.
It should be clearer that there may be other chunks between the 'fmt ' and the 'data' chunks, for example, the 'bext' chunk that would normally be found in an AES31-2 file.

A revised PWD will be posted as soon as possible.