341 lines
11 KiB
JavaScript
341 lines
11 KiB
JavaScript
/*jshint browser:true, bitwise:false */
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/*globals DOMLoader, MidiFile, App */
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/**
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* file.js
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*
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* Read MIDI files
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*/
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(function () {
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'use strict';
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/**
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* Note
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*
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* Represent a note object
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*/
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function Note(options) {
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options = options || {};
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this.note = options.note || 0;
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this.channel = options.channel || 0;
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this.start = options.start || 0;
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this.length = options.length || 1;
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}
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/**
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* Channel
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*
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* Represent a channel object
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*/
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function Channel(id) {
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this.id = id;
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this.meta = {};
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this.program = 0;
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this.sound = true;
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this.notes = true;
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this.pending = {};
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}
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/**
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* Convert stained data
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*
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* @param {data: string}
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* @return string
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*/
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function convertStained(data) {
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var converted, length, i;
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converted = [];
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length = data.length;
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for (i = 0; i < length; i += 1) {
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converted[i] = String.fromCharCode(
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data.charCodeAt(i) & 255
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);
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}
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return converted.join("");
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}
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/**
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* Push note on pending notes stack
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*
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* @param {meta: Object} Meta object for this song
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* @param {event: Object} Event describing noteOn
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* @param {time: int} Starting time
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*/
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function pushNote(meta, event, time) {
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var channel = event.channel,
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note = event.noteNumber;
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meta.channels[channel].pending[note] = new Note({
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start: time,
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channel: channel,
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note: note
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});
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}
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/**
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* Pop note from given stack and add it to notes list
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*
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* @param {meta: Object} Meta object for this song
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* @param {event: Object} Event describing noteOff
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* @param {time: int} Ending time
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*/
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function popNote(meta, event, time) {
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var channel = event.channel,
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note = event.noteNumber,
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data;
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data = meta.channels[channel].pending[note];
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if (data === undefined) {
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return;
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}
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data.length = time - data.start;
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meta.length = Math.max(
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meta.length,
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time
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);
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meta.notes.push(data);
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delete meta.channels[channel].pending[note];
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}
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/**
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* Load file
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*
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* @param {url: string} Path to file
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* @return Promise
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*/
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function loadFile(url) {
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return new window.Promise(function (resolve, reject) {
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var fetch = new XMLHttpRequest();
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fetch.open('GET', url);
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fetch.overrideMimeType('text/plain; charset=x-user-defined');
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fetch.onreadystatechange = function () {
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if (this.readyState === this.DONE) {
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// wait for next tick before resolving, since
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// not found errors are triggered after readyState
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// change event
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window.setImmediate(function () {
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resolve(fetch.responseText);
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});
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}
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};
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fetch.onerror = function () {
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reject(new Error(
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'Le fichier demandé est introuvable.'
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));
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};
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fetch.send();
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});
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}
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/**
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* Import given MIDI file and translate
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* MIDI data object
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*
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* @param {url: string} Path to MIDI file
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* @return Promise
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*/
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function parseData(data) {
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return new window.Promise(function (resolve, reject) {
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var tracks, events, tracksLength, eventsLength, length,
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event, i, j,
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// parsing data
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timeline = [], meta = {},
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channelPrefix = null, metaObject,
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// timing
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time, bpm = 120, tpb,
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firstNote = +Infinity, offset;
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// check MIDI structure and load events
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data = convertStained(data);
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try {
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data = new MidiFile(data);
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} catch (err) {
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if (err === 'Bad .mid file - header not found') {
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reject(new Error(
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'Le fichier n\'est pas un fichier MIDI ' +
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'valide. Ce logiciel ne prend en charge ' +
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'que les fichiers de type MIDI.'
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));
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} else {
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reject(new Error(
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'Le fichier MIDI n\'est pas correctement ' +
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'formé. Il contient une erreur qui ' +
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'empêche le logiciel de le lire ' +
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'correctement. Veuillez rapporter ' +
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'ce problème aux auteurs du fichier.'
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));
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}
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}
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tracks = data.tracks;
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tracksLength = tracks.length;
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tpb = data.header.ticksPerBeat;
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// prepare meta object
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meta = {
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names: [],
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instruments: [],
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channels: [],
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notes: [],
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markers: [],
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copyright: '',
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lyrics: '',
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length: 0
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};
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// init channels
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length = 16;
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for (i = 0; i < length; i += 1) {
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meta.channels[i] = new Channel(i);
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}
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// parse all events
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for (i = 0; i < tracksLength; i += 1) {
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time = 0;
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events = tracks[i];
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eventsLength = events.length;
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for (j = 0; j < eventsLength; j += 1) {
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event = events[j];
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// time of each event is relative from last track event
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if (event.deltaTime) {
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time += event.deltaTime / tpb / (bpm / 60);
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}
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if (event.type === 'meta') {
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if (event.subtype === 'midiChannelPrefix') {
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channelPrefix = event.channel;
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} else {
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if (channelPrefix !== null) {
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metaObject =
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meta.channels[channelPrefix];
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} else {
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metaObject = meta;
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}
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}
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switch (event.subtype) {
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case 'trackName':
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metaObject.names[i] = event.text;
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break;
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case 'copyrightNotice':
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metaObject.copyright = event.text;
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break;
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case 'lyrics':
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metaObject.lyrics = event.text;
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break;
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case 'instrumentName':
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metaObject.instruments[i] = event.text;
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break;
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case 'marker':
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metaObject.markers.push({
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time: time,
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text: event.text
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});
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break;
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case 'setTempo':
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bpm = 60000000 / event.microsecondsPerBeat;
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break;
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}
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} else if (event.type === 'channel') {
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channelPrefix = null;
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switch (event.subtype) {
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case 'noteOn':
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firstNote = Math.min(firstNote, time);
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pushNote(meta, event, time);
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timeline.push({
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type: 'noteOn',
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time: time,
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note: event.noteNumber,
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channel: event.channel,
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velocity: event.velocity
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});
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break;
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case 'noteOff':
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popNote(meta, event, time);
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timeline.push({
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type: 'noteOff',
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time: time,
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note: event.noteNumber,
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channel: event.channel
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});
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break;
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case 'noteAftertouch':
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timeline.push({
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type: 'noteAftertouch',
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time: time,
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note: event.noteNumber,
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channel: event.channel,
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amount: event.amount
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});
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break;
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case 'controller':
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timeline.push({
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type: 'controller',
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time: time,
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subtype: event.controllerType,
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value: event.value,
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channel: event.channel
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});
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break;
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case 'programChange':
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meta.channels[event.channel].program =
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event.programNumber;
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break;
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}
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}
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}
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}
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// normalize starting time: always have 1s delay
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if (firstNote < +Infinity) {
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offset = 1 - firstNote;
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}
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meta.length += offset;
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length = timeline.length;
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for (i = 0; i < length; i += 1) {
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event = timeline[i];
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if (event.time + offset < 0) {
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event.time = 0;
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} else {
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event.time += offset;
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}
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}
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length = meta.notes.length;
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for (i = 0; i < length; i += 1) {
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meta.notes[i].start += offset;
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}
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resolve({
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meta: meta,
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timeline: timeline
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});
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});
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}
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App.MIDI.file = {
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load: loadFile,
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parse: parseData
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};
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}()); |