MIDI.PLAY works out the notes by listening to the recording. That's a hard problem, so the result is a strong first draft, not a perfect score. The most common slip is one long held note coming out as several short ones.
The note editor
Choose Edit notes on a song. The editor shows a piano roll: time runs left to right and pitch bottom to top, so each note is a bar you can grab.
- Move a note by dragging it.
- Lengthen or shorten it by dragging its right edge.
- Add a note by holding ⌥ or ⌘ and clicking empty space.
- Select several by dragging a box around them.
- Delete with the Delete key.
- Undo and redo any change.
Tips
- Listen while you edit. A wrong note usually sounds wrong before it looks wrong.
- If one instrument came out messy, splitting the song into instruments before working out the notes often gives a much cleaner result.