International organisation for standardisation organisation internationale de normalisation

Further discussion

The Chair presented

m16765

Audio Liaison Statement from IFPI

IFPI via SC29 Secretariat

The Chair noted that IFPI and RIAA appear to give full support to the proposed profile.

Takehiro Moriya, NTT, made a short presentation concerning the resources that NTT Electronics and Napster Japan/Tower Records could bring to support the proposed profile.

It is the consensus of the Audio Subgroup to adopt the proposed MPEG-4 ALS Baseline Profile and to issue it at this meeting as PDAM, assuming the review by Requirements is positive and Requirements also endorses starting at the PDAM level.

Ralph Sperschneider, FhG, presented

m16702

Proposed revision of WD on AAC family of profiles

Ralph Sperschneider

The contribution notes that the current text specifies profiles as follows:

Tools	Block Lengths Supported
	1024	960 & 1024
AAC	AAC Profile
AAC + SBR	HE-AAC Profile
AAC + SBR + PS	HE-AAC V2 Profile	AAC Common Profile

It proposes to add text that explains the intent of the profile change and clarifies some portions of the text. In addition, proposes to create new profiles such that all combinations of tools and block lengths are available as profiles, as shown here:

Tools	Block Lengths Supported
	1024	960 & 1024
AAC	AAC Profile	AAC Common Profile
AAC + SBR	HE-AAC Profile	HE-AAC Profile
AAC + SBR + PS	HE-AAC V2 Profile	HE-AAC V2 Profile

Finally, it proposes to share profile and level indications as is used by the existing “1024 only” profiles.

Kristofer Kjörling, Dolby, presented a few slides giving Dolby’s view on the proposal. He anticipates a problem in the following case:

• 
  DAB+ 960 block length “over the air” content is stored in an MP4 file
  
• 
  The profile and level indication does not convey whether the content is 960 or 1024 block length
  
• 
  Devices that do not support 960 may play this incorrectly.
  

Finally, the presenter stated emphatically that it is a bad idea to have a profile and level indication that means two things (e.g. AAC Profile or AAC Common Profile).

Bernhard Grill, FhG, noted that there is a bit in the audioConfig information that signals the block length (960 or 1024). Hence the question is what fraction of fielded equipment read this bit (and can decide not to play 960 block length material) and what fraction of equipment does not have to read it since they can play both 960 and 1024.

Concerning Profile and Level signalling , Kristofer Kjörling, Dolby, make the following summary of the situation:

• 
  Dolby proposal: new Profile and Level signalling for new profile
  
  • 
    Clean solution, new Profile and Level indication for new profile
    
  • 
    Small number of legacy players won’t play new profile (current Profile and Level aware 960 AAC family implementations)
    
  • 
    Does not remove the old profiles
    
• 
  FhG proposal, use the same Profile and Level signalling for old and new profiles
  
  • 
    All legacy 960 devices will play
    
  • 
    Creates new confusion -- you cannot distinguish profiles on a file level
    
  • 
    The old profiles are ”paper tigers,” i.e. they are part of the text but cannot be explicitly indicated (basically re-doing the old standard with new name)
    
  • 
    Risk of malfunction on a large number of legacy devices
    

It is the consensus of the Audio Subgroup to adopt the text from the contribution that explains the intent of the profile change and clarifies some portions of the text into the WD on AAC family of profiles.