Organisation internationale de normalisation

5.2Task Group discussions

5.2.1MPEG-2 and MPEG-4 audio, conformance, reference software

Heiko Purnhagen, Dolby, presented

m15786

Proposed Draft Corrigendum on AAC-ELD

Per Ekstrand Markus Schnell

Backward compatible signalling of SBR in AAC-ELD is not allowed. The contribution proposes that this restriction should be more prominent in the specification. Furthermore, it notes an error in aliasing cancelling tool for Low Power mode (i.e. real-valued filterbanks) and gives the correct phase factor that should be used.

It was the consensus of the Audio Subgroup to incorportate the proposed Part 3 changes in the current DCOR under ballot and the Part 5 changes in the PDAM to be produced at this meeting.

Takehiro Moriya, NTT, presented

m15861

Information related to the proposed ALS profile

Noboru Harada Tilman Liebchen Takehiro Moriya Yutaka Kamamoto

This noted that the principal customer for the proposed ALS profile has withdrawn its support, and hence recommends that this profile remain at WD status.

Schuyler Quackenbush, Audio Research Labs, presented

m15794

Suggested profile name for ALS

A. G. Tescher for USNB

This contribution suggested a new name for the proposed ALS profile. The Audio Subgroup agreed that since this profile will not progress to CD status, discussions on profile naming can be postponed until such progression occurs.

Takehiro Moriya, NTT, presented

m15860

Proposed Corrigenda on MPEG-4 ALS

Noboru Harada Tilman Liebchen Takehiro Moriya Yutaka Kamamoto

This contribution presented a number of technical corrections required in the ALS specification, as either the textual specification or the reference software.

It was the consensus of the Audio Subgroup to incorporate the proposed changes into AMD 2/DCOR 4 of the ALS specification and into a new Dcor to ALS conformance and reference software. The Chair noted that it would be best to issue the conformance Dcor at the next meeting against MPEG-4 Part 26, the new part that will contain all MPEG-4 Audio conformance.

Andreas Schneider, Dolby, presented

m15876

Proposed study on coupling channel fixes

Andreas Schneider

Based on the information in the contribution, it was the consensus of the Audio Subgroup to issue a Study on 13818-7 Dcor1 and Study on 14496-3 Dcor 6.

Yasushige Nakayama, NHK, presented

m15807

Issues of AudioBIFS to applying to an Advancement of Satellite Digital Broadcasting in Japan

Yasushige Nakayama

The presenter reviewed NHK’s original proposal. This extends MPEG-2 AAC’s original implicit channel mapping for the horizontal plane by proposing similar syntax in the AAC fill element for a “top” plane and a “bottom” plane. In addition, NHK requests that there be an additional entry in the MPEG-4 AAC channel configuration table for the 22.2 loudspeaker case.

Johannes Boehm, Thomson, presented

m15866

Report on flexible signaling of audio channels to loudspeaker mapping using MPEG-4 BIFS

Juegren Schmidt Mario Sieck

The contribution reported on how BIFS could be used to map the individual AAC decoded channel signals to the associated loudspeakers. It reported that the data rate and computational complexity are moderate in the context of the Hi-Vision system data rate. It was agreed to conduct an AhG activity in which the following standards bodies are contacted to determine if they have specified means to map coded audio channels to loudspeakers:

• 
  AES
  
• 
  TC100
  

Ralph Sperschneider, FhG, noted that a 22.2 channel MPEG-2 AAC program in which the PCE signals only 10 channels (the “mid” plane of the 22.2 program), legacy decoders might crash due to input buffer overflow. It was agreed to study the MPEG-2 changes requested by ARIB in a break-out to meet at 1200 today. Participants are at least Ralph Sperschneider, S. Quackenbush, Yasushige Nakayama.