Audio Files overview

[last updated: 2022-12-15]
Midi
Audacity
OBS Studio
Audio Recorder notes
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• Formats:
  • Lossless:
    wav, wma, aiff & alac (Apple), flac, mqa
  • Lossy:
    mp3, aac, ogg
    m4a is an mpeg-4 file. They use aac codec. It has tighter compression and higher quality than mp3, but is still lossy.
  • See Programs/apps below for techniques for changing between formats

• Metadata:

• Programs/apps to read/extract metadata:
  • ffmpeg
    • Convert m4a to wav:
      • $ ffmpeg -i input.mp4 output.wav
      • Convert all m4a files in a directory,:
        for f in *.m4a; do ffmpeg -i "$f" "${f/%m4a/wav}"; done

  • Script files to extract/edit metadata:
    • Rename and convert a bunch of music files:
      • I have hundreds of .m4a music files that I want to convert to .mp3 format.
        Having so many, I want to convert them in batches using a script file.
        This command will convert them:
        $ ffmpeg -i [filename-minus-extension].m4a [filename-minus-extension].mp3
      • The filenames I need to convert are of all sorts:
        many start with 2 or 3 numeric characters (presumably track numbers)
        many have "special" characters, ie non-English-alphabet characters
        eg. from Spanish or Turkish or wherever

        many have eg. "Track 14" as part (or all) of their filename
        many have spaces

      • I want to:
        remove all the spaces,
        remove any numeric characters at the start of the filename
        replace any special characters with nearest English equivelent
        preserve track numbers embedded in the filename
        add characters to discriminate between what will surely be multiple files with the same name, eg. "Track 14"

  • Editing metadata:

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