chomens-bot-js/util/midi_converter/main.js

/* eslint-disable max-len */
/* eslint-disable require-jsdoc */
const {Midi} = require('@tonejs/midi');
const {convertNote, convertPercussionNote} = require('./convert_note.js');

function convertMidi(midi) {
  if (!(midi instanceof Midi)) throw new TypeError('midi must be an instance of require(\'@tonejs/midi\').Midi');

  let noteList = [];
  for (const track of midi.tracks) {
    for (const note of track.notes) {
      const mcNote = (track.instrument.percussion ? convertPercussionNote : convertNote)(track, note);
      if (mcNote != null) {
        noteList.push(mcNote);
      }
    }
  }

  noteList = noteList.sort((a, b) => a.time - b.time);

  // It might be better to move some of this code to the converting loop (for performance reasons)
  let maxVolume = 0.001;
  for (const note of noteList) {
    if (note.volume > maxVolume) maxVolume = note.volume;
  }
  for (const note of noteList) {
    note.volume /= maxVolume;
  }

  let songLength = 0;
  for (const note of noteList) {
    if (note.time > songLength) songLength = note.time;
  }

  return {name: midi.header.name, notes: noteList, loop: false, loopPosition: 0, length: songLength};
}

module.exports = {convertMidi, convertNote, convertPercussionNote};