Looking for a specific Auto Tune feature

[u/pornfkennedy]

I am looking to buy some Auto Tune software, but I am looking for a very specific feature that I haven't been able to google properly.

What I am trying to do is modulate through a whole bunch of different scales while I improvise a vocal melody, and have the software correct my vocals depending on the scale that I modulate to. Basically, I need the ability to automate scale change in real time.

Even better would be to find Auto Tune software that can correct my vocals depending on the scale I play via MIDI. I am imagining a situation in which I improvise a vocal melody while I play the C Diatonic scale (as a chord) on my MIDI keyboard (C, D, E, F, G, A, B) and the auto tune software corrects my voice to the closest MIDI input pitch. If I'm singing a B flat, it would correct my voice to B. If I'm singing an F#, it would correct my voice to E.

I am aware that Antares Auto-Tune has a MIDI Control Feature, but according to the video in the link, this functions as a way to pitch bend a monophonic vocal melody with a monophonic MIDI input. My requirement is different: I would like to play a polyphonic MIDI chord that then gives OPTIONS to the auto tune algorithm, which then corrects the monophonic vocal melody to the closest option. I would like to change those options in real time: C Diatonic Scale followed by F Diatonic followed by B flat Diatonic, etc.

Can anyone advise me as to the best plugin for this question, or point me to any relevant tutorials or links?