rncbc.org a.k.a. Rui Nuno Capela

Melodyne is a great product and surely is a great tool that targets one niche problem domain; amalgamating the best of both worlds together, audio and MIDI. Being real-time is key to its prompt success, absolutely. That is and still is its world class advantage and that's a good thing, nevertheless.

Now, back in the open-source/free-software side of the trench, if one can say that without raising eyebrows, there are a few great and fairly awesome tools that approach the same problem, but in quite different and general ways. One could say it's better, with a broader audience, but that's just me telling you a bunch of BS :)

Having that said, please have a look to Sonic Visualiser for a starter. It might have the foundation and the what not you're after. Bear in mind, it's not Melodyne, and never it can or would. Says me :)

Byee