[FFmpeg-trac] #3563(avformat:new): wrong duration reported by ffmpeg

FFmpeg trac at avcodec.org
Fri Apr 18 09:47:05 CEST 2014

#3563: wrong duration reported by ffmpeg
             Reporter:  chinshou    |                    Owner:
                 Type:  defect      |                   Status:  new
             Priority:  normal      |                Component:  avformat
              Version:  git-master  |               Resolution:
             Keywords:  wav mp3     |               Blocked By:
             Blocking:              |  Reproduced by developer:  0
Analyzed by developer:  0           |
Changes (by jamal):

 * keywords:  mp3 => wav mp3
 * component:  undetermined => avformat


 The file contains a 'fact' chunk, and the wav demuxer is using it to
 calculate the duration, whereas other players seem to be ignoring it.
 The value of the chunk is 10423511, which when divided by the sample rate
 gives 7:52 minutes. If you then divide that by number of channels you get
 the actual length of 3:56.

 The spec says that the 'fact' chunk value should be number of samples per
 channel, so chances are the value in this file is wrong (being total
 samples across all channels instead of samples per channel), but I don't
 have any other stereo non-pcm wav files with 'fact' chunks to verify that.

Ticket URL: <https://trac.ffmpeg.org/ticket/3563#comment:3>
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