Convert .m4a files that don't work with Spotify to ones that do

fix_m4a.sh

#!/bin/bash
for filename in *.m4a
do ffmpeg -i "$filename" -acodec copy -movflags faststart "s-$filename"
done

Usage.md

How to use (macOS)

1. $ brew install ffmpeg --with-fdk-aac --with-tools --with-freetype --with-libass --with-libvorbis --with-libvpx --with-x265
   a. You probably will only need the --with-fdk-aac flag, but I'm not sure.
2. $ cd into the directory with the files you want to fix.
3. Place the fix_m4a file into that directory (remove the .sh file extension)
4. $ chmod 700 fix_m4a to allow you to run it
5. $ ./fix_m4a This will fix all the .m4a files, creating fixed versions prefixed with s-.