MIDI event handler
manuroe
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e15a168152
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/*
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Copyright 2014 matrix.org
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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String.prototype.endsWith = function(suffix) {
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return this.indexOf(suffix, this.length - suffix.length) !== -1;
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};
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var MidiEventHandler = {
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midiQueue: [],
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startTime: 0,
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vexTabString: "",
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currentMeasureTime: 0,
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perLine: -1,
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init: function () {
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MIDI.loadPlugin({
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soundfontUrl: "./soundfont/",
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instrument: "acoustic_grand_piano",
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callback: function () {
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/*
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var delay = 0; // play one note every quarter second
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var note = 50; // the MIDI note
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var velocity = 127; // how hard the note hits
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// play the note
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MIDI.setVolume(0, 127);
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MIDI.noteOn(0, note, velocity, delay);
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MIDI.noteOff(0, note, delay + 0.75);
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*/
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}
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});
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},
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reset: function() {
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this.vexTabString = "";
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this.currentMeasureTime = 0;
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this.perLine = -1;
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this.ready = false;
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this.beat = 0;
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this.intial4Timings = [];
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this.renderer = new Vex.Flow.Renderer($('#boo')[0],
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Vex.Flow.Renderer.Backends.CANVAS);
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this.artist = new Vex.Flow.Artist(10, 10, 750, {scale: 0.8});
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this.vextab = new Vex.Flow.VexTab(this.artist);
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// key is the note string, value its midi_ts value when it went to ON
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this.notesON = {};
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},
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/*
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vextab.parse("tabstave notation=true tablature=false \n\
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notes 4-5-6/3 ## =|: 5-4-2/3 2/2 =:|\n\
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\n\
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tabstave notation=true tablature=false\n\
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notes C-D-E/4 #0# =:: C-D-E-F/4 =|=");
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artist.render(renderer);
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*/
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setReady: function() {
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this.ready = true;
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this.render();
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},
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handleEvent: function(event) {
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if (0 === this.beat)
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{
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// We do not know the beat yeat
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// Wait for 4 notes to compute the tempo
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if ("on" === event.content.state) {
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this.intial4Timings.push(parseInt(event.content.midi_ts));
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if (4 === this.intial4Timings.length) {
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// un beat: duree d'un temps
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this.beat = (this.intial4Timings[3] - this.intial4Timings[0]) / 3;
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console.log("## beat: " + this.beat);
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}
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}
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return;
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}
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var vexNote = this.getVexNote( this.getMidiNote(event.content.note) );
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if ("on" === event.content.state) {
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this.notesON[vexNote] = parseInt(event.content.midi_ts);
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}
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else if (this.notesON[vexNote])
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{
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// How long the note last
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var duration = parseInt(event.content.midi_ts) - this.notesON[vexNote];
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delete this.notesON[vexNote];
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var fraction = duration / this.beat;
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console.log(fraction);
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var musicFraction;
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var duration = Math.floor(Math.log2(1 / fraction)) - 1;
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switch (duration) {
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case 4:
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musicFraction = "w";
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break;
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case 2:
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musicFraction = "h";
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break;
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case 1:
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musicFraction = "q";
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break;
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case 0:
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musicFraction = "8";
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break;
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case -1:
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musicFraction = "16";
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break;
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case -2:
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musicFraction = "32";
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break;
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}
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this.currentMeasureTime += duration;
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vexNote = ":" + musicFraction + " " + vexNote;
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this.addNote(vexNote);
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}
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},
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c: function(fraction) {
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return Math.floor(Math.log2(1 / fraction)) - 1;
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},
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addNote: function (vexNote) {
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if (-1 === this.perLine)
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{
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// Create a new line
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if ("" !== this.vexTabString) {
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// Add a line break with the previous line
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this.vexTabString += "\n";
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}
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this.vexTabString += "tabstave notation=true tablature=false clef=treble time=C\nnotes ";
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this.perLine = 0;
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}
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this.vexTabString += vexNote;
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console.log(this.currentMeasureTime);
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if (this.currentMeasureTime >= 4) {
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this.perLine = this.perLine + 1;
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if (this.perLine <= 3) {
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this.vexTabString += " | ";
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}
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else {
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// Break the line
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this.vexTabString += "\n";
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this.perLine = -1;
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}
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this.currentMeasureTime = 0;
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}
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else {
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this.vexTabString += " ";
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}
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if (this.ready) {
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this.render();
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}
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},
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getVexNote: function(midiNote) {
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return midiNote;
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// TODO: manage this
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var vexNote;
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if (2 === midiNote.length) {
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if (this.vexTabString.endsWith('#')) {
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vexNote = midiNote[0] + 'n/' + midiNote[1];
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}
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else
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{
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vexNote = midiNote[0] + '/' + midiNote[1];
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}
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}
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return vexNote;
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},
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getMidiNote: function(midiNoteNumber) {
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var noteString = [ "C", "C#", "D", "D#", "E", "F", "F#", "G", "G#", "A", "A#", "B" ];
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var octave = Math.floor(midiNoteNumber / 12) - 1;
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var noteIndex = (midiNoteNumber % 12);
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return noteString[noteIndex] + "/" + octave;
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},
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render: function() {
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console.log("####\n" + this.vexTabString);
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this.vextab.reset();
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this.artist.reset();
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this.vextab.parse(this.vexTabString);
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this.artist.render(this.renderer);
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}
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};
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