Re: I'm actually surprised that it works on raw samples at all
I agree, also to me it seems counterintuitive using wave forms instead of score, e.g. midi. Especially, as I believe that it would be easier to detect/learn the structures of a piece of music from musical notations rather than from wave forms. (Having played and failed with artificial neural networks doing midi many moons ago, I might be a bit biased though.)
On second thought, it is maybe not a bad idea. Musical notations are, after all, only a limited language to describe music. They are not music. Going back to the actual music, which is much closer represented by wave forms than notations, might be an interesting approach.
Haven't listened to the samples yet. I'm curious how they sound, being first samples. And comparing to how far "AI midi" got (or didn't go) in all the years it's been around...