How to tell if an m4a file is lossless

[Stefan Monnier]

How can I tell (from a script) if some *.m4a file is using the AAC codec
or the ALAC codec?


Stefan

[Eduardo M KALINOWSKI]

Post by Stefan Monnier
How can I tell (from a script) if some *.m4a file is using the AAC codec
or the ALAC codec?

One possibility is to use ffmpeg -i filename and then parse the
output. (Grepping for the strings used in each codec should give the
answer.)

[Stefan Monnier]

Post by Eduardo M KALINOWSKI

Post by Stefan Monnier
How can I tell (from a script) if some *.m4a file is using the AAC codec
or the ALAC codec?

One possibility is to use ffmpeg -i filename and then parse the
output. (Grepping for the strings used in each codec should give
the answer.)

Indeed, that did the trick: the stderr either include "Audio: alac" or
"Audio: aac".
Thank you,


Stefan

[lee]

Post by Stefan Monnier
How can I tell (from a script) if some *.m4a file is using the AAC codec
or the ALAC codec?

Unpack it and compare it to the "original" unpacked file?

Perhaps the packer leaves a signature somewhere in the packed file to
tell an unpacker what it is. If you can find the signature or take a
look at the source of the unpacker, you might be able to find out how
to check what it is.