aac muxed to mp4, renamed to m4a, won't play

[Xichael]

I've used Yamb to demux the aac from some mp4 videos (http://www.youtube.com/user/iamamiwhoami/feed), mux them back, audio only, then rename them to m4a. So far, the files have played fine everywhere I've tried them (MediaMonkey, VLC, iTunes, Sony car stereo), except my Creative Zen.

My question is, are there differences between an m4a produced by iTunes (assuming that's what the Zen is designed to play), and an mp4 produced by Yamb (MP4Box) then renamed to m4a?

Are there any other (non-MP4Box) muxers I should try?

[Chug a Bug]

I have the same trouble with my Fuze+, it simply ignores anything M4A unless created by iTunes. The demuxed AAC audio plays just fine but M4A it doesn't want to know.

There must be something specific to iTunes thats not reproduced elsewhere. I also tried remuxing to M4A with FFMPEG but nope, nothing, nada, not working.

I can demux to AAC with YAMB or FFMPEG but I lose all tag metadata and have an "unknown artist/unknown track", very frustrating.

[filler56789]

MP4Box has an "-ipod" command-line switch, have you already tried it?

-ipod rewrites the file for iPod