So, iTunes, by default, imports CDs to m4a (MPEG-4 audio w/AAC), which is based on the QuickTime file format.
I'd ripped a bunch of my CDs to .m4a when I had iTunes on the laptop provided by my employment at WPI, but I had to give that laptop back when I got laid off in early 2004. I still had the m4a files, though, and preferred not to have to re-rip those CDs if possible.
XMMS, at least at the time, was the best of a less than stellar breed of music players, but it didn't know m4a. There were a couple of plugins out there that tried to fill the gap, but none of them seemed to quite make it. So I, being unemployed and thus possessed of much time, took up the various widely-distributed bases of code and attempted to forge a plugin out of them which was up to my own standards. I think I did pretty well.
I'm making my libm4a xmms plugin freely available for use. Thus far, a few friends have tried it successfully, on both FreeBSD and Linux, so it's possible that I've managed to make it properly cross-platform. If anyone who finds this has problems with it, I'd appreciate any improvements that could be provided. Suggestions are welcome.
(It would appear that XMMS has since gone defunct, although there are successor projects, at least some of which apparently have m4a support. That would thus make my offering a bit silly, but what the heck, I may as well keep it up, as an instructional exercise for other programmers if nothing else.)