Homebrew dev plum released a new version of the Mp3PlayerPlugin Lite for 5.00 M33, 5.03HEN, 5.50GEN, 6.20TN und 6.35 PRO!
With this plugin you're able to hear your own music in PSP games.
Controls (translated by me):- Added the ability to read the folder. (Mp3play.ini please see)
- From reading all folders under the folder to load the MP3 file as far as your memory.
· MP3 to ensure that memory to match the length of the path of the file.
DownloadL + R + Left / Right = select other songs
2. L + R +  = Pause
3. L + R + O = Change the order of play (in order, randomly, etc.)
4. L + R + Triangle = Play the song again.
5. L + R + Up / Down = change in volume.