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I want to be able to listen to the content already recorded. The file contains Opus stream in MP4 container and it is recorded from Internet using ffmpeg (4.4.2).

$ ffprobe -hide_banner file.m4a
[mov,mp4,m4a,3gp,3g2,mj2 @ 0xa9000800] moov atom not found
file.m4a: Invalid data found when processing input
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  • ffmpeg -i source.mp4 -vn audio.wav && ffmpeg -i audio.wav audio.m4a That should recover the audio. Video must be re-encoded to fix a missing moov.
    – JayCravens
    Commented Apr 23 at 18:11
  • @JayCravens The first command fails with the aforementioned error.
    – jarno
    Commented Apr 24 at 18:27
  • Ouch. It's expected though. Will it re-encode? Try: ffmpeg -i source.mp4 -c:v libx264 -c:a aac -crf 10 -preset ultrafast -shortest -movflags +faststart re-encode.mkv
    – JayCravens
    Commented Apr 24 at 19:21

1 Answer 1

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I succeeded making my files playable by using https://github.com/anthwlock/untrunc With that you probably need a working file from the same source besides the broken file.

I followed instructions in the README: built the tool "With system libraries" and used the tool like instructed. You get help about the options by untrunc -h, but you might not need any options. The tool is for video, but seems to work for pure audio files, too.

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  • Explaining HOW you used this tool in order to solve the problem will make this an answer. Currently, this is only a comment. Please EDIT this post to make it a full answer.
    – music2myear
    Commented Apr 25 at 0:14

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