The Megabox uses a bit more complicated compressing algorithm, but otherwise the MIDI data is in MIDI format. The lyric part is a bit interesting also, but not too complicated to decode.
Here's the first version of the Megabox2Midi program. I hard-coded the offsets to decode Vietnamese songs only, you could play with the code to decode the other languages. The program also spits out mp3 chunks with the delay time when it supposes to play appended to the end if the file name(s) -- if the song got vocal that is.
Have fun!
MegaBox2Midi.zip
