[Ffmpeg-devel] Dubious field in AAC-ADTS
Fri Jun 10 19:02:22 CEST 2005
"Nico Sabbi" <nsabbi at fastwebnet.it> writes:
>>"Nico Sabbi" <nsabbi at fastwebnet.it> writes:
>>> I don't fully understand what's the meaning of the field
>>> "no_raw_data_blocks_in_frame" described here:
>>> Is it the number of audio frames carried in the current
>>> ADTS packet or what else? If not, can I always assume that
>>> an ADTS packets always carries exactly 1 AAC frame?
>>That field specifies the number of raw_data_block elements that
>>follow. Each raw_data_block decodes into 1024 or 960 samples for each
>>channel. See ISO 14496-3, section 4.5.2. Does this answer your
> yes: crystal-clear as usual :)
> BTW, in the sources of libfaad2 there's a comment stating that
> a the 2-bits field present in the specs of ADTS-4 (emphasis
> IIRC) but not in ADTS-2 were removed
> from the specs of ADTS-4, effectively making the two frames
> syntaxes identical, except for the ID field.
Yes, the emphasis field was removed in Corrigendum 1 to 14496-3. ISO
will actually give you this document in exchange for nothing but your
> Did you ever find some sample coded with 'emphasis'?
Not that I know of. I haven't looked for it, though.
mru at inprovide.com
More information about the ffmpeg-devel