How AI Quantization works
Last updated November 2, 2026
AI Quantize is a small machine learning model that turns a MIDI recording made with Live MIDI into sheet music. Flat built it, and it runs on your device, in your browser or in the Flat app. We keep improving it.
What it does
A MIDI keyboard records when you pressed each key and how long you held it. It does not record the rhythm you meant. AI Quantize reads the whole take and works out the note values, where the bars fall and which staff each note belongs on. A fixed grid moves each note to the nearest line instead, so a note played a little late can land on the wrong beat.
How it was trained
The model learned from scores, not from recordings of people:
- Public-domain scores. We used scores whose licence is public domain or CC0, so anyone may reuse them.
- Simulated performances. From each score, we generated performances that play it the way a person would, with uneven timing and the occasional slip. The model learns to go from that playing back to the written score.
Your data
AI Quantize was not trained on Flat users' scores, imports or takes. Your scores and recordings are not used to train Flat's AI models. See AI in Flat.
- It runs on your device. The model downloads once, then reads your take in your browser or in the Flat app.
- Feedback is optional. After you place a take, Flat may ask how close the result was to what you played. You can skip it.
- No AI credits. AI Quantize does not use AI credits.
- It is optional. Choose No AI in your AI settings to hide it.
Transparency
- The notes are yours. AI Quantize does not write music. It only decides how the notes you played are written down, so the pitches stay the ones you played.
- It is not generative AI. It adds nothing to your music, so a score made with it is not labeled as AI-generated and can still be published in the community. See Is a score made with AI labeled?.
- You stay in control. You can switch back to a grid, undo, or edit any note before you save.
What to expect
AI Quantize is a best reading of your playing, not a guarantee. It works best on piano-style music played with the Metronome on, and it can struggle with very fast passages, strong tempo changes, or takes where you stop and restart. Use the note editing tools to fix what is left before you save.
Frequently asked questions
Should I use a grid or AI Quantize?
Use a grid when you played evenly to the metronome. Try AI Quantize when you played freely or with changing tempo. You can switch back and forth before you place the take. See Which grid should I choose?.
Does AI Quantize send my recording to Flat?
The model reads your take on your device. If you choose to answer the feedback question, Flat receives your answer.