I'm trying to program a harmonizer, like Jacob Collier's one built by MIT's Ben Bloomberg. I am looking for good, accessible resources on pitch shifting (whilst still sounding natural) and other terms I've heard like format shifting.
Where are some good resources for this for somebody with extensive programming experience but no experience in audio processing?
For example, many of them don’t have great low end. Some are “sluggish” and need external enveloping. Getting a sense for what’s out there can help to provide a North Star when you write your own. Some classics are the Eventide H3000, IZotope Vocal Synth, TC Voice Live, Antares Harmony Engine, and Soundtoys Little Alterboy.