[FFmpeg-trac] #2691(FFmpeg:new): ffmpeg detects 0 channels in audio streams

[FFmpeg]

#2691: ffmpeg detects 0 channels in audio streams
-------------------------------------+-------------------------------------
             Reporter:  vhann        |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:  FFmpeg       |                  Version:
             Keywords:  vob dvd aac  |  unspecified
  0 channels                         |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug:
 ffmpeg does not detect the audio channels if the audio streams don't have
 any in the first few seconds.

 How to reproduce:
 {{{
 vhann at vhanndinateur ~,0 $ foo/ffmpeg -i outputShortest.vobffmpeg version
 N-54023-g6fe419b Copyright (c) 2000-2013 the FFmpeg developers
   built on Jun 14 2013 05:12:40 with gcc 4.6 (Debian 4.6.3-1)
   configuration: --prefix=/root/ffmpeg-static/32bit --arch=x86_32 --extra-
 cflags='-m32 -I/root/ffmpeg-static/32bit/include -static' --extra-
 ldflags='-m32 -L/root/ffmpeg-static/32bit/lib -static' --extra-
 libs='-lxml2 -lexpat -lfreetype' --enable-static --disable-shared
 --disable-ffserver --disable-doc --enable-bzlib --enable-zlib --enable-
 postproc --enable-runtime-cpudetect --enable-libx264 --enable-gpl
 --enable-libtheora --enable-libvorbis --enable-libmp3lame --enable-gray
 --enable-libass --enable-libfreetype --enable-libopenjpeg --enable-
 libspeex --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-version3
 --enable-libvpx
   libavutil      52. 35.101 / 52. 35.101
   libavcodec     55. 16.100 / 55. 16.100
   libavformat    55.  8.102 / 55.  8.102
   libavdevice    55.  2.100 / 55.  2.100
   libavfilter     3. 77.101 /  3. 77.101
   libswscale      2.  3.100 /  2.  3.100
   libswresample   0. 17.102 /  0. 17.102
   libpostproc    52.  3.100 / 52.  3.100
 [mpeg @ 0xaaa3060] max_analyze_duration 5000000 reached at 5005000
 microseconds
 Input #0, mpeg, from 'outputShortest.vob':
   Duration: 00:00:24.46, start: 0.140600, bitrate: 17150 kb/s
     Stream #0:0[0x1bf]: Data: dvd_nav_packet
     Stream #0:1[0x1e0]: Video: mpeg2video (Main), yuv420p, 720x480 [SAR
 32:27 DAR 16:9], 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc
     Stream #0:2[0x82]: Audio: ac3, 0 channels
     Stream #0:3[0x81]: Audio: ac3, 0 channels
     Stream #0:4[0x80]: Audio: ac3, 0 channels
 At least one output file must be specified
 }}}

 -analyzeduration and -probesize make it work though:
 {{{
 vhann at vhanndinateur ~,0 $ foo/ffmpeg -analyzeduration 50000000 -probesize
 50000000 -i outputShortest.vob
 ffmpeg version N-54023-g6fe419b Copyright (c) 2000-2013 the FFmpeg
 developers
   built on Jun 14 2013 05:12:40 with gcc 4.6 (Debian 4.6.3-1)
   configuration: --prefix=/root/ffmpeg-static/32bit --arch=x86_32 --extra-
 cflags='-m32 -I/root/ffmpeg-static/32bit/include -static' --extra-
 ldflags='-m32 -L/root/ffmpeg-static/32bit/lib -static' --extra-
 libs='-lxml2 -lexpat -lfreetype' --enable-static --disable-shared
 --disable-ffserver --disable-doc --enable-bzlib --enable-zlib --enable-
 postproc --enable-runtime-cpudetect --enable-libx264 --enable-gpl
 --enable-libtheora --enable-libvorbis --enable-libmp3lame --enable-gray
 --enable-libass --enable-libfreetype --enable-libopenjpeg --enable-
 libspeex --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-version3
 --enable-libvpx
   libavutil      52. 35.101 / 52. 35.101
   libavcodec     55. 16.100 / 55. 16.100
   libavformat    55.  8.102 / 55.  8.102
   libavdevice    55.  2.100 / 55.  2.100
   libavfilter     3. 77.101 /  3. 77.101
   libswscale      2.  3.100 /  2.  3.100
   libswresample   0. 17.102 /  0. 17.102
   libpostproc    52.  3.100 / 52.  3.100
 [mpeg @ 0xa8d21e0] max_analyze_duration 50000000 reached at 50032489
 microseconds
 Input #0, mpeg, from 'outputShortest.vob':
   Duration: 00:00:24.50, start: 0.095889, bitrate: 17118 kb/s
     Stream #0:0[0x1bf]: Data: dvd_nav_packet
     Stream #0:1[0x1e0]: Video: mpeg2video (Main), yuv420p, 720x480 [SAR
 32:27 DAR 16:9], 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc
     Stream #0:2[0x80]: Audio: ac3, 48000 Hz, 5.1(side), fltp, 384 kb/s
     Stream #0:3[0x82]: Audio: ac3, 48000 Hz, 5.1(side), fltp, 384 kb/s
     Stream #0:4[0x81]: Audio: ac3, 48000 Hz, 5.1(side), fltp, 384 kb/s
 At least one output file must be specified
 }}}

 llogan and vulture both were valuable in figuring the problem.

-- 
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2691>
FFmpeg <http://ffmpeg.org>
FFmpeg issue tracker