[matroska-devel] AAC profiles /matroska codec IDs

Christian HJ Wiesner chris at matroska.org
Wed Feb 19 14:12:41 CET 2003


MPEG-2 AAC Low Complexity / LC profile
MPEG-2 AAC Main profile
MPEG-4 AAC LC profile
MPEG-4 AAC Main profile
MPEG-4 AAC Long Term Prediction / LTP
MPEG-4 AAC Scalable Sampling Rate / SSR
MPEG-4 AAC Version 2
MPEG-4 AAC Version 3 coming soon...

Seems i have to create a few more codec IDs than the existing 2 :-( ??

Right now we have :

10. 'A_MPEG2_AAC' ; Audio, AAC, MPEG2 standard

11. 'A_MPEG4_AAC' ; Audio, AAC , MPEG4 standard

Of course Ivan Dimkovic was the one to clarify here, but i doubt he 
would want to support matroska development with respect to AAC audio, 
maybe he proves me wrong one day :D .

I guess the interesting question for us was the compatibiity with 
existing en/decoders. For example it is said in the thread that MPEG4 
AAC LC and MPEG2 AAC LC only differ by a few bytes in the AAC header ( 
dont aks me though what the sense is behind differentiating here 8)
  ), and maybe we strip the AAC from the MP4 container in any case, so 
we dont have to care at all ?

The more i read that the more i get the intention we had to 
differentiate between

AAC main profile
AAc V2

and not care at all about the differences between MPEG4 and MPEG2, as 
those seem to be onyl container related ? What do you all think ?

Roberto, would you care to clarify for our list ( cc : rjamorim ) ?



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