Function split_at_attacks 

pub fn split_at_attacks(notes: &NoteList, levels: &StemLevels<'_>) -> NoteList

Splits each note where the stem has an attack of its own inside it.

The decoder can read a low repeat with a short gap as part of one long note, so no later step sees two notes. A frame inside a note marks a dip when it is no louder than the frame before it, quieter than the frame after it, and ATTACK_DIP or more below the loudest frame in the ATTACK_AFTER after it. The split falls on the last envelope reading at or below the first share of RISE_SPAN of the loudest reading in that span, before the first reading at the second share after the quietest of the dip frame’s readings, and the note’s fundamental must dip by FUNDAMENTAL_DIP across it. It holds when the piece from there has an attack of its own after the piece before it, by the rule of the split join, which then keeps the two apart. Each piece keeps the note’s key, octave flag and velocity.

A last piece of at most twice ATTACK_AFTER that runs into the decoder’s next note of its key, within SPLIT_GAP, starts that note instead, unless that note has an attack of its own after the piece. The decoder can start a note 58 ms after its attack, which leaves such a piece. A repeat after a gap of 20 ms or less can show no attack by the rule of the split join, so the limit keeps a longer piece before one a note of its own. A gated repeat of 60 to 90 ms after such a gap still loses its onset to the piece before it.