How do I join AAC/.m4a files via CLI (Mac OS X)

Question

I need to quickly join a number of separate m4a files in to one large one. Is there any way to do so via CLI on in Mac OS X?

Answer 1

Unfortunately AAC files cannot be joined by simple concatenation, which is what I assume you mean when you mention doing it via the command line?

If you installed something like ffmpeg then you could certainly build up a process to take in AAC audio files, convert them to the uncompressed wave data, join them all up, then export the resulting file back to AAC again.

Alternately, if using the CLI is not a hard requirement then you could do this with iTunes and Audacity.

Answer 2

I think I found a way myself without any transcoding nessesary, with some inspiration from Coxys answer. MP4Box lets me do it: MP4Box -cat file1.m4a -cat file2.m4a output.m4a. It doesn´t retain any metadata but for my purpose its just fine.

Now, given Coxys answer, are there any pitfalls with the file I just haven´t discovered yet?