RollTab

RollTab is a free iOS app that turns your MIDI piano into an AI-powered music autocomplete tool. Built on a 125M-parameter transformer trained specifically for piano continuation, it listens to what you play and generates a real-time continuation—think GitHub Copilot, but for piano. Because the model runs on-device, it achieves roughly 108 notes per second on an iPhone 15, well above the speed needed for live playing. The app solves the challenge of real-time AI music generation by using a custom MIDI note representation that encodes pitch, delta onset, duration, and velocity in a single token, avoiding common issues like note-off drift and speeding up inference. Sustain pedal is handled during preprocessing, so note durations reflect actual pedal use. RollTab is for pianists, composers, and hobbyists who have a MIDI keyboard and an iPhone/iPad. Simply connect your keyboard, play a short prompt, and let the model continue the piece in the style you started.