Function min_note_frames 

pub fn min_note_frames(bpm: Bpm) -> usize

The minimum note length for a BPM, in model frames.

The rule takes half a sixteenth note, 0.5 * 15000 / BPM ms, within 58 to 127.7 ms, and rounds it to whole frames, half to even as the decoder does. The decoder drops a note that lasts this many frames or fewer, so a kept note lasts at least one frame more. 60 BPM gives 11 frames, 90 BPM 7 and 120 BPM 5.