Dan Tepfer (Human - Computer Duet) - NPR Music Tiny Desk Concert

Video Link

I decided to post this as a text topic since IMO the video description is really important to understanding this performance:

Aug. 29, 2019 | Colin Marshall -- Dan Tepfer has transformed the acoustic piano entirely with his new project, Natural Machines. Watch the keys and you'll see this Disklavier — a player piano — plucking notes on its own. But it's not a prerecorded script.

Here's how it works: Tepfer plays a note, and a computer program he authored reads those notes and tells the piano what to play in response. Tepfer can load different algorithms into the program that determine the pattern of playback, like one that returns the same note, only an octave higher. Another will play the inverted note based on the center of the piano keys. These rules create interesting restrictions that Tepfer says make room for thoughtful improvisation. In his words, he's not writing these songs, so much as writing the way they work. To better communicate what's happening between him and the piano, Tepfer converted these audio-impulse data into visualizations on the screen behind him, displaying in real time the notes he plays followed by the piano's feedback. We dive even deeper into this project in a recent Jazz Night in America video piece.

Perhaps the trickiest part here, unlike a human-to-human duo, is that the computer plays along with 100 percent accuracy based solely on Tepfer's moves. He compares it to dancing with a robot that never misses a beat. Tepfer has to play in kind to keep the train on the tracks, but if he falls out of step, so does the computer. On the other hand, Tepfer has unlocked a new frontier of music available to acoustic piano players: He's essentially given himself more limbs to play the piano at once, and at times we see more than 10 keys pressed at a time or a sequence of notes played at seemingly superhuman speeds. It's a central idea to what innovative technology enables for us — that which is impossible for us to achieve on our own.

edit: Nice related video from Jazz Night in America with Dan explaining some of how it works:
https://www.youtube.com/watch?v=0L6tzG3FkcU