[Ffmpeg-devel] Re: [PATCH] faad decoding error return

Baptiste COUDURIER baptiste.coudurier
Sun Mar 5 04:07:01 CET 2006


M?ns Rullg?rd wrote:
> [...]
> 
> That's not the problem here.  The audio is incorrectly detected as
> 24000 Hz sample rate.  Forcing it to 48000 makes it sound much more
> sensible.
> 

>From faad2:

/* no SBR signalled, this could mean either implicit signalling or no
SBR in this file */
/* MPEG specification states: assume SBR on files with samplerate <=
24000 Hz */

if (mp4ASC->samplingFrequency <= 24000)
   {
      mp4ASC->samplingFrequency *= 2;
      mp4ASC->forceUpSampling = 1;
   } else /* > 24000*/ {
      mp4ASC->downSampledSBR = 1;
   }

Thats why sampling rate is 48000. But we can only know that when faad
has been inited. In MOV demuxer that means parsing much extradata.
I will see what can I do.

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