In short, a RealTrack performance is an audio file where someone is playing an instrument over many chord changes of various lengths (bar, half bar, beat level). However, you never deal directly with RealTracks like this.

Instead, you specify a chord sequence in BiaB interface - basically, like in a spreadsheet. BiaB automatically pulls the chords out of the selected RealTrack to match the order you specify.

The algorithm works at the bar/half bar/beat level, not by working on the material at the note level. It can force the notes to match the chords via pitch shifting, but that's not generally what happens.

Think of it sort of alike automatic loop assembly. Obviously, there are a finite number of chords in any given RealTrack, but they're generally long and diverse enough that it isn't a problem.

As to how well it works, you can check out the demos here: https://www.pgmusic.com/tutorial_realtrackslist.htm

-- David Cuny
My virtual singer development blog

Vocal control, you say. Never heard of it. Is that some kind of ProTools thing?