If you feel like this example could be improved, you may edit this example here.
-c:a aac song.m4a
For iTunes / iPods, we need the AAC coded, in the M4A container.
-map_metadata 0:s:a:0
Metadata for OGG tracks is stored at the stream level, so if you just try to copy metadata it won’t work, since the AAC encoder can only store global metadata. That’s what this bit does.
-aac_pns 0
AAC added a feature called “perceptual noise substitution” which iPods don’t support, so this needs to be disabled.
