Music
From PSPWiki
The PSP is capable of playing music encoded in MP3, Sony's ATRAC3 format, and ACC (if using firmware 2.0), loaded on to a Memory Stick Duo or a Memory Stick Pro Duo. Sony is also talking to various studios about releasing Albums on the UMD.
You can also extract music from games with the proper tools, for use on your computer, iPod, memory stick, etc.
The most common source for AAC music is Apple's iTunes. Music downloaded from the Apple music store is DRM protected and is incompatible with the PSP. Music ripped via iTunes from a CD or other source in AAC format is compatible.
To use AAC music, you must simply rename the file from the apple extension of .m4a to .mp4. No ID3 tags are supported with firmware 2.0.

