i have a bunch of .m4a files in one folder, 1000s. can i automate their conversion somehow?

  • rollingflower@lemmy.kde.social
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    7 months ago

    No as both are lossy codecs you will always lose quality doing so. You can do it with ffmpeg.

    parallel ffmpeg -i {} {.}.opus ::: *.m4a
    

    You may want to tweak parameters for bitrate, etc. But this is not needed at all, as AAC had patents that are now expired.

    If you get .flac, .wav or similar lossless music, you should encode that with opus. But lossy to lossy makes nearly no sense (apart from specific players not supporting them)

    • zurohki@aussie.zone
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      7 months ago

      GNU Parallel works well for this kind of thing. A lot of audio stuff is single threaded, so unlike video transcoding running multiple conversions simultaneously is a useful thing to do. The command is simpler, too:

      parallel ffmpeg -i {} {.}.opus ::: *.m4a
      
    • Otherbarry@lemmy.zip
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      7 months ago

      If you get .flac, .wav or similar lossless music, you should could encode that with opus.

      Fixed.

      Unless you have a strong stance against people storing lossless files of their music? But I don’t think that’s quite what you meant :)

  • M. Orange@beehaw.org
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    7 months ago

    Unless the m4a files are ALAC-encoded, you shouldn’t do it. m4a files tend to hold AAC-encoded audio, which is a lossy format. Opus is also a lossy format, so you’ll only lose sound quality, basically. You should only convert lossless to lossy.

  • ArcaneSlime@lemmy.dbzer0.com
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    7 months ago

    If you’re on linux try navigating to the folder in the terminal and running

    for i in *.m4a; do ffmpeg -i "$i" "${i%.*}.opus"; done

      • ArcaneSlime@lemmy.dbzer0.com
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        7 months ago

        Well sure always back up everything but this command will create new .opus files still leaving the original .m4a in the folder too, so even if it errors just delete the bad .opus files and try to resolve your ffmpeg codec issue before retrying the conversion or trying another method. Ffmpeg in my experience always converts with the “makes a new file with your file(s)” method, I’ve never had it do the “change the file destructively” method.

        • Max-P@lemmy.max-p.me
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          7 months ago

          It’ll also error out or prompt to overwrite an existing file unless a flag is passed that tells it to overwrite unattended.

          • ArcaneSlime@lemmy.dbzer0.com
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            7 months ago

            Sure, but if it errors out no harm no foul, and don’t pass any flags to overwrite the input file which I had not included above.

            While I’m thinking about it, what is that flag? Because afaik ffmpeg can’t overwrite and convert the file simultaneously, you have to use a temp file.

            • Max-P@lemmy.max-p.me
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              7 months ago

              That’s the point: you have to go out of your way to accidentally overwrite your input files with ffmpeg.

              And no it indeed can’t output to the same file as input.

  • hperrin@lemmy.world
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    7 months ago

    Opus is lossy, so no. But they’re already stored in a lossy format, so you probably won’t notice a difference if you use the same bitrate.