[SOLVED] How to join MP4 files where some have more than one audio stream?

[yetanotherlogin]

Hello

I need to join three MP4 files, where, for some reason, the last two have two audio files:

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'file1.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    creation_time   : 2036-02-06 06:28:16
    encoder         : HandBrake 0.10.2 2015060900
  Duration: 00:12:52.10, start: 0.000000, bitrate: 525 kb/s

    Stream #0:0(und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p(tv, bt709), 720x410 [SAR 8651:8640 DAR 211:120], 390 kb/s, 30 fps, 30 tbr, 90k tbn, 180k tbc (default)
    Metadata:
      creation_time   : 2036-02-06 06:28:16
      handler_name    : VideoHandler

    Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 128 kb/s (default)
    Metadata:
      creation_time   : 2036-02-06 06:28:16
      handler_name    : Stereo

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'file2.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    creation_time   : 2036-02-06 06:28:16
    encoder         : HandBrake 0.10.2 2015060900

  Duration: 00:13:50.77, start: 0.000000, bitrate: 750 kb/s
    Stream #0:0(und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p(tv, bt709), 720x406 [SAR 406:405 DAR 16:9], 356 kb/s, 30 fps, 30 tbr, 90k tbn, 180k tbc (default)
    Metadata:
      creation_time   : 2036-02-06 06:28:16
      handler_name    : VideoHandler

    Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 160 kb/s (default)
    Metadata:
      creation_time   : 2036-02-06 06:28:16
      handler_name    : Stereo

    Stream #0:2(und): Audio: ac3 (ac-3 / 0x332D6361), 44100 Hz, stereo, fltp, 224 kb/s
    Metadata:
      creation_time   : 2036-02-06 06:28:16
      handler_name    : Stereo
      
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'file3.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    creation_time   : 2036-02-06 06:28:16
    encoder         : HandBrake 0.10.2 2015060900

  Duration: 00:07:34.67, start: 0.000000, bitrate: 673 kb/s
    Stream #0:0(und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p(tv, bt709), 720x406 [SAR 406:405 DAR 16:9], 279 kb/s, 30 fps, 30 tbr, 90k tbn, 180k tbc (default)
    Metadata:
      creation_time   : 2036-02-06 06:28:16
      handler_name    : VideoHandler

    Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 160 kb/s (default)
    Metadata:
      creation_time   : 2036-02-06 06:28:16
      handler_name    : Stereo

    Stream #0:2(und): Audio: ac3 (ac-3 / 0x332D6361), 44100 Hz, stereo, fltp, 224 kb/s
    Metadata:
      creation_time   : 2036-02-06 06:28:16
      handler_name    : Stereo

If I use ffmpeg the standard way, in the output, the last two parts have no audio.

Does someone know how to 1) check which audio stream actually has audio, and 2) tell ffmpeg to use that audio stream?

Thank you.

[JVRaines]

You can use ffplay with the -ast option to specify one or the other of the audio streams to check their content. Then run ffmpeg with the -map option to specify the audio stream you want to output.

[pandy]

https://trac.ffmpeg.org/ this one should help

[yetanotherlogin]

Thanks much for the infos.

Here's how to play a video by using a specific audio stream:

ffplay -ast 1 -i input.mp4

And here's how to tell ffmpeg to include the video stream and use that audio stream in the output file:

ffmpeg -i input.mp4 -map 0:v -map 0:a:1 output.mp4