Hi,
It is notoriously difficult to get a good MIDI file from an audio file, especially if there is more than a single instrument playing anything much more than a melody line. Bottom line is you really can't expect to take any kind of audio file and get sheet music from it except by working to transcribe it yourself (
Notation Composer is a good fit for this kind of work.)
Taking any audio file and trying to separate out the instruments or voices (different instruments/voices playing the same note pitch or chordal notes), the notes themselves (determining what is a root note versus the harmonics), the root pitch (versus vibrato or reverb), the duration (whether the note is still playing or if that’s some ringing echo in the recording) and a host of other nuances is a very difficult technological task. Our ears and brains work in an incredibly complex way to discern all these aspects of music. Getting a program to do the same thing, and then produce a MIDI file (the “directions” for playing the piece) so that we can get sheet music is still a goal yet to be fully realized.
There are a number of programs that claim to do this, but in all the testing we’ve done, none of them do a good enough job to produce a MIDI that doesn’t still need a lot of work to give decent sheet music. Even the Melodyne Editor, which does an absolutely amazing job of separating audio tones, still doesn’t give a very good MIDI file for getting sheet music (though it can be used in sequencers to give a performance). It's not that smart folks aren't trying their best, it's just a very difficult task to do well.
You can bet that when we find a good one, we’ll let folks know!
ttfn,
Sherry