Well, actually it's just about opening the device and instead of sending the data to a file, you simply write it to the mp3 decoder (CMD_WRITE). You won't be able to use the niffy plugins though, as you don't get back the pulse coded sample data from the mp3 decoder. Therefore, writing a wrapper to the mpega.library is IMHO not reasonable (because mpega.library is used to decode the mp3 data asynchroneously and get back the PCM data, and play this PCM data back through AHI or Paula (or do whatever you want to it). The Commodore MPEG-Device takes the raw MP3 data and plays it back synchroneously. It actually outputs the sound, so AHI and stuff is not needed.