Yeah... good luck.
For starters, you can't really analyze a mp3 at all until it is decompressed (to a wave file, preferably). Even then you would need some seriously advanced software to make out individual notes from that. As a matter of fact, I would say it is most likely close to impossible to make such a program that is error-free; filtering different sounds from one another is very hard, let alone doing so programmatically. Then you are to find each of these notes pitch, which, if it is a live instrument, probably differs a bit in frequency over time (ok, so you can comparisionably easily round it to the closest "clean note" pitch, but still).
Well, then imagine ie. a door being opened in the background of the recording. What will an analyzing program make out of that? And so on. There are software that do this I think, but that only works with a clearly distinct
monophonic signal.
Sorry, but that's probably how it is.
