[FFmpeg-devel] AC3 samples per frame?

[Justin Ruggles]

Nico Sabbi wrote:
> Hi,
> if I read the specs correctly in EAC3 the number of samples per frame 
> should be given by 256*number of audio blocks, where the number of
> audio blocks should be
> -6 if fscod==3
> - {1,2,3,6}[next two bits]  otherwise
> correct?
> I have a sample where frmsiz==127  and fscod2==6,
> thus the corresponding frame should extend for 256 bytes
> (frmsz+1)*2 and include 1536 samples (6*256) that doesn't
> look correct to me.
> 
> (the sample in mphq is  samples/A-codecs/AC3/eac3/eac3mono64kbit.eac3)
> 
> Can anyone explain if I misunderstood the specs?

fscod2 is only 2 bits, so it can't be 6.  It is only used to indicate 
reduced samplerates (24kHz, 22.5kHz, 16kHz).

frmsiz=127 does indeed mean that the frame is 256 bytes.

what is the value of fscod and numblkscod?

-Justin