[FFmpeg-trac] #513(avcodec:open): FFMpeg is unable to find the aac codec parameters for mp4 file

FFmpeg trac at avcodec.org
Sun Apr 8 00:11:56 CEST 2012


#513: FFMpeg is unable to find the aac codec parameters for mp4 file
--------------------------------------+-----------------------------------
             Reporter:  workcutter@…  |                    Owner:
                 Type:  defect        |                   Status:  open
             Priority:  normal        |                Component:  avcodec
              Version:  git-master    |               Resolution:
             Keywords:  aac mov       |               Blocked By:
             Blocking:                |  Reproduced by developer:  1
Analyzed by developer:  0             |
--------------------------------------+-----------------------------------

Comment (by reimar):

 How was that file created? It is clearly invalid, it claims the audio is
 coded as two channels, but there is only one (+ parametric stereo, so it
 looks like two, but still only one is encoded).
 The below patch proves that by fixing playback (but of course will break
 any non-mono AAC file)
 {{{
 --- a/libavcodec/mpeg4audio.c
 +++ b/libavcodec/mpeg4audio.c
 @@ -89,6 +89,7 @@ int avpriv_mpeg4audio_get_config(MPEG4AudioConfig *c,
 const uint8_t *buf,
      c->object_type = get_object_type(&gb);
      c->sample_rate = get_sample_rate(&gb, &c->sampling_index);
      c->chan_config = get_bits(&gb, 4);
 +c->chan_config = 1;
      if (c->chan_config < FF_ARRAY_ELEMS(ff_mpeg4audio_channels))
          c->channels = ff_mpeg4audio_channels[c->chan_config];
      c->sbr = -1;
 }}}

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/513#comment:6>
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