Magic Quill: A Real-time Score Engraving System for Live MIDI Performances

We present Magic Quill, a browser-based system that visualizes live MIDI performances as an evolving engraved score. An online beat tracker produces provisional notation immediately, while an asynchronous offline model revises earlier measures as additional musical context becomes available. On consumer hardware, the online model requires approximately 0.13 ms per note and browser-based online beat-tracking inference completes within approximately 10 ms; offline refinement arrives after several seconds and achieves competitive transcription accuracy using substantially less context than prior offline systems. A demonstration of our proposed system is available at https://magicquill.github.io.