I'm not exactly sure if such program exists but my idea is to create a program which could recognize a melody and convert it into accords and notes as well. This would be very helpful and useful for guitarists and other musicians to avoid wasting much time. This program will be easy to use, simply press a button "open a file" then press "convert" and save as txt format file button or something like this. This program could also receive a sound from microphone, recognize and covert it into tabs, accords or notes as well. What do you think about it?