OpenOMR is an open source optical music recognition (OMR) tool for printed music scores. It allows a user to scan a printed music partition and play it through the computer speakers.
It was hard to find how it works, e.g. what specifications should the score meet, size, no lyrics in-between, what's an FFT image and where is it good for, etc. Eventually I got it working, but it does not work good with scores having multiple voices. Only with a single voice. Also it seems there's no difference in the length of a whole note and a half note. The idea of a program playing MIDI from a score is a great idea. But I can't use this program in this way.