Greetings,
I've got an interesting problem..
I can play mp3s and m4as fine, but I cant write the id3 tags on the m4a files and can't figure out why for the life of me. Anything I'm missing?

I think it's your tagger, try easytag or the Amarok tagger. The reason iirc is that taglib doesn't support m4a so you'll need a tagger that doesn't use it.

Amarok never worked-- its what I use for music and where I noticed the problem.

Easytag pretends to write the tag but the tag is gone when I exit the program and open it again in Amarok.

Any more ideas?

I don't have any m4a's anymore and only other thing I can think of is to use a Windows program under wine, iTunes even.

Hmmm - Amarok worked for me, could it be that Fedora doesn't support m4a's.

*shudders*... Windows...
I'm sure Fedora does not come with the library needed -- .m4a is a proprietary format.
My biggest question here is what library am I missing? libid3tag clearly only covers mp3s.
I like Fedora largely because it comes clean of proprietary bullshit and binary blobs of code. Sure you can install them when needed (as I do) but in general you have a Free & Open OS when you receive it. I do not know if that is true of Suse.

Anyway... maybe you could poke around on your own machine and see what is letting you write the m4a tags?

per a search using smart:
perl-MP4-Info & pacpl

sorry.. but.. what?!

I did a search using Smart (used for package management) to show what packages installed had m4a in the description and that was the result.

All I can tell you is that EasyTag and Amarok work for me, maybe you're not saving your tags when leaving Easytag - you need to do a "save files" (either menu or icon).