I am not sure if the is the right section to post this but I will try here anyway.

I have a program called Sibelius I downloaded that takes midi files and converts it into sheet music. Problem is I dont want to have to search for midi files for all the songs in my library. So I was wondering if anyone knows of a mp3 to midi converter for macs? I have been searching for one but I cant seem to find any that work.

midi technology doesn't work like that. it would be like trying to make orange juice by smashing apples.

an mp3 is just a compressed audio file.

a midi file is more like a database file that sounds like music when read by an appropriate device. basically a midi file tracks what notes and pitches are supposed to be played by whatever instrument for the track but the actual sound you hear when you listen to a midi file is determined by the quality of the midi sound bank on the soundcard in your pc.

Well, I did manage to find this:

http://www.versiontracker.com/dyn/moreinfo/macosx/29260

Now, I've never used it, and can't image it would be very effective, but you can give it a shot if you like.

Generally, all the MIDI files you'll find have been painstakingly created and transcribed by individual musicians, and will be much more accurate.

Honestly, though, I think doing a Google search is going to be much quicker and easier than trying to sit through a dubious conversion process like what you're hoping to do. The thought of a piece of software trying to distinguish all the various timbers of a musical piece to create discrete MIDI tracks, and then plotting out musical frequency ranges as MIDI note numbers seems close to impossible to me, but again, I haven't tried it.

Note: Also, I don't know if Sibelius supports VST plug-ins -- you'd need to have a host DAW of some sort to use that plug-in.