A piano melody, and fingers that follow the notes

Leon Lin asked GPT-6 Astra for two things that have to agree: a piano melody, and a 3D pianist whose fingers follow the actual notes. The whole build took about two hours. The performance in the clip runs a few minutes.

Finger animation is where musical visuals usually lie. Hands bounce in the right neighborhood of the keyboard while the audio does something else. Here the claim is correspondence. The note you hear is the key the finger chose.

Composition and performance coming from the same pass is why that correspondence was even available. The score was not handed to an animator as a finished file. It was written by the thing that then had to play it.