Organisation internationale de normalisation

Lossless Coding of Pitch Lag

Experts in the group noted that it would be very interesting if the CE proponent would:

• 
  Report on re-training of Huffman codebooks
  
• 
  Provide additional performance information on impact of using only bits allocated from TCX to ACLEP.
  

It was the consensus of the Audio subgroup to take another step in this CE, as specified in the Status and Workplan for USAC CEs.
Bitstream Issues

An open issue is whether the following proposed bitstream changes should be adopted into the USAC DIS:

• 
  MPS 212 changes, both Config and MPS data.
  
• 
  Independency flag
  

Heiko Purnhagen, Dolby, reported that for mono signals the Independency flag saves 4 bits whenever it is set and for stereo signals saves 8 bits whenever it is set. Hence, for mono signals, if the flag is set every 4 frames there is not net change in bitrate. In broadcast applications, this would permit “break-in” to a maximum latency to the Independency flag frame of approximately one-half second (1600 kHz sampling rate).

It was the consensus of the Audio subgroup to adopt these changes.
Global Gain

As already discussed during the week, a bug was identified in this CE.

It was the consensus of the Audio subgroup to take another step in this CE, as specified in the Status and Workplan for USAC CEs.