Homebrew coder plum's MP3PlayerPlugin lets PSP users listen to their favorite MP3 tracks while playing games on Sony's PlayStation Portable handheld. It's basically an updated version of the old music.prx plugin with even more features such as different play modes. It even lets you play music while you're on the PSP XMB. It also doesn't use up a lot of memory.

Changelog v1.9 (Google translated from Japanese):

• Removed CPU is still unstable patch changes.
• SYSCALL because they are absolutely frozen patch
• SRC CHANNEL MUTE MUTE function only can be changed to.
• MP3 changed the kernel memory so as to ensure the list of file paths.

Changelog v1.9 fix:

• MUTE function back to the original
• Operation and adjustment of other
• Hiraku Kimi source

Changelog v1.9 fix 2:

• sceKernelLoadExecVSHWithApitype patch to fix a bug in the function part