I was looking for a freeware that could pitchbend a soundtrack like one of a monologue or a commercial, with a MIDI file, so that the track would sound like the MIDI file. I wanted to do something like the Slap Chop Rap.

-I know there's a sticky, I couldn't find anything that I was looking for there, so don't slam me on that.

Pirate Fruity Loops.

The effect is called autotune. If you've ever heard of T-Pain, he uses the same thing. Autotune is actually a pitch correction application found in most high-end music production softwares like Cubase, but by tweaking certain settings, you can achieve a more abrupt pitch change like in a T-Pain song, or a more natural sounding pitch change like in the Slap Chop Rap.

If you have Fruity Loops, you can find a freeware VST called G-Snap which could achieve the same effect. I think Melodyne can also perform an autotune effect, but it's not freeware.