[FFmpeg-user] Is mixing of audio channels happening by default in ffmpeg?

Thu Jul 18 15:07:50 CEST 2013

I have an uncompressed Quicktime with 8 tracks of audio (in addition to it's one video and one Timecode track). I am transcoding it to Quicktime Prores with the following command line (and results):

"ffmpeg-20130507-git-399f6ef-win64-static\bin\ffmpeg.exe" -i "C:\Users\root\Desktop\MultiChannel.mov" -vcodec prores_ks -pix_fmt yuv444p10le -profile:v 3 -acodec copy -t 1 -f mov "D:\\MultiChannel\MultiChannel.mov"
ffmpeg version N-52837-g399f6ef Copyright (c) 2000-2013 the FFmpeg developers
  built on May  7 2013 01:14:14 with gcc 4.7.3 (GCC)
  configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libcaca --enable-libfreetype --enable-libgsm --enable-libilbc --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libx264 --enable-libxavs --enable-libxvid --enable-zlib
  libavutil      52. 29.100 / 52. 29.100
  libavcodec     55.  7.100 / 55.  7.100
  libavformat    55.  4.101 / 55.  4.101
  libavdevice    55.  0.100 / 55.  0.100
  libavfilter     3. 63.101 /  3. 63.101
  libswscale      2.  2.100 /  2.  2.100
  libswresample   0. 17.102 /  0. 17.102
  libpostproc    52.  3.100 / 52.  3.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 000000000239e760] Stream #1: not enough frames to estimate rate; consider increasing probesize
[mov,mp4,m4a,3gp,3g2,mj2 @ 000000000239e760] Stream #2: not enough frames to estimate rate; consider increasing probesize
[mov,mp4,m4a,3gp,3g2,mj2 @ 000000000239e760] Stream #3: not enough frames to estimate rate; consider increasing probesize
[mov,mp4,m4a,3gp,3g2,mj2 @ 000000000239e760] Stream #4: not enough frames to estimate rate; consider increasing probesize
[mov,mp4,m4a,3gp,3g2,mj2 @ 000000000239e760] Stream #5: not enough frames to estimate rate; consider increasing probesize
[mov,mp4,m4a,3gp,3g2,mj2 @ 000000000239e760] Stream #6: not enough frames to estimate rate; consider increasing probesize
[mov,mp4,m4a,3gp,3g2,mj2 @ 000000000239e760] Stream #7: not enough frames to estimate rate; consider increasing probesize
[mov,mp4,m4a,3gp,3g2,mj2 @ 000000000239e760] Stream #8: not enough frames to estimate rate; consider increasing probesize
[mov,mp4,m4a,3gp,3g2,mj2 @ 000000000239e760] Stream #9: not enough frames to estimate rate; consider increasing probesize
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'C:\Users\root\Desktop\MultiChannel.mov':
  Metadata:
    major_brand     : qt
    minor_version   : 537199360
    compatible_brands: qt
    creation_time   : 2013-07-17 21:37:47
  Duration: 00:00:45.05, start: 0.000000, bitrate: 1199347 kb/s
    Stream #0:0(eng): Video: rawvideo (raw  / 0x20776172), rgb24, 1920x1080, 1193199 kb/s, SAR 1:1 DAR 16:9, 23.98 fps, 23.98 tbr, 239760 tbn, 239760 tbc
    Metadata:
      creation_time   : 2013-07-17 21:37:47
      handler_name    : Apple Alias Data Handler
      timecode        : 00:59:45:00
    Stream #0:1(eng): Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz, mono, s16, 768 kb/s
    Metadata:
      creation_time   : 2013-07-17 21:40:27
      handler_name    : Apple Alias Data Handler
    Stream #0:2(eng): Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz, mono, s16, 768 kb/s
    Metadata:
      creation_time   : 2013-07-17 21:40:28
      handler_name    : Apple Alias Data Handler
    Stream #0:3(eng): Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz, mono, s16, 768 kb/s
    Metadata:
      creation_time   : 2013-07-17 21:40:28
      handler_name    : Apple Alias Data Handler
    Stream #0:4(eng): Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz, mono, s16, 768 kb/s
    Metadata:
      creation_time   : 2013-07-17 21:40:29
      handler_name    : Apple Alias Data Handler
    Stream #0:5(eng): Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz, mono, s16, 768 kb/s
    Metadata:
      creation_time   : 2013-07-17 21:40:30
      handler_name    : Apple Alias Data Handler
    Stream #0:6(eng): Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz, mono, s16, 768 kb/s
    Metadata:
      creation_time   : 2013-07-17 21:40:30
      handler_name    : Apple Alias Data Handler
    Stream #0:7(eng): Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz, mono, s16, 768 kb/s
    Metadata:
      creation_time   : 2013-07-17 21:40:31
      handler_name    : Apple Alias Data Handler
    Stream #0:8(eng): Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz, mono, s16, 768 kb/s
    Metadata:
      creation_time   : 2013-07-17 21:40:31
      handler_name    : Apple Alias Data Handler
    Stream #0:9(eng): Data: none (tmcd / 0x64636D74)
    Metadata:
      creation_time   : 2013-07-17 21:40:32
      handler_name    : Apple Alias Data Handler
      timecode        : 00:59:45:00
Output #0, mov, to 'D:\\MultiChannel\MultiChannel.mov':
  Metadata:
    major_brand     : qt
    minor_version   : 537199360
    compatible_brands: qt
    encoder         : Lavf55.4.101
    Stream #0:0(eng): Video: prores (prores_ks) (apch / 0x68637061), yuv444p10le, 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 11988 tbn, 23.98 tbc
    Metadata:
      creation_time   : 2013-07-17 21:37:47
      handler_name    : Apple Alias Data Handler
      timecode        : 00:59:45:00
    Stream #0:1(eng): Audio: pcm_s16le (sowt / 0x74776F73), 48000 Hz, mono, 768 kb/s
    Metadata:
      creation_time   : 2013-07-17 21:40:27
      handler_name    : Apple Alias Data Handler
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo -> prores_ks)
  Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
frame=   24 fps=2.5 q=0.0 Lsize=    8082kB time=00:00:01.00 bitrate=66139.3kbits/s dup=276 drop=0
video:7986kB audio:94kB subtitle:0 global headers:0kB muxing overhead 0.024802%

The resulting quicktime appears to contain a single audio track with the contents of original 8 tracks mixed together. I have not provided any audio filtering/mixing options. Wouldn't the default condition to be passing through of the audio tracks exactly as the source contains it? If not, is it possible to pass each track through as such or must it be explicitely told to do so? Ideally if provided with 8 tracks, the resulting file would have 8 tracks.

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