326 lines
8.7 KiB
JavaScript
326 lines
8.7 KiB
JavaScript
/*
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----------------------------------------------------------
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Web Audio API - OGG or MPEG Soundbank
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----------------------------------------------------------
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http://webaudio.github.io/web-audio-api/
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----------------------------------------------------------
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*/
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(function(root) { 'use strict';
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window.AudioContext && (function() {
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var audioContext = null; // new AudioContext();
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var useStreamingBuffer = false; // !!audioContext.createMediaElementSource;
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var midi = root.WebAudio = {api: 'webaudio'};
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var ctx; // audio context
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var sources = {};
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var effects = {};
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var masterVolume = 127;
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var audioBuffers = {};
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///
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midi.audioBuffers = audioBuffers;
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midi.send = function(data, delay) { };
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midi.setController = function(channelId, type, value, delay) { };
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midi.setVolume = function(channelId, volume, delay) {
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if (delay) {
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setTimeout(function() {
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masterVolume = volume;
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}, delay * 1000);
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} else {
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masterVolume = volume;
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}
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};
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midi.programChange = function(channelId, program, delay) {
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// if (delay) {
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// return setTimeout(function() {
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// var channel = root.channels[channelId];
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// channel.instrument = program;
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// }, delay);
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// } else {
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var channel = root.channels[channelId];
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channel.instrument = program;
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// }
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};
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midi.pitchBend = function(channelId, program, delay) {
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// if (delay) {
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// setTimeout(function() {
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// var channel = root.channels[channelId];
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// channel.pitchBend = program;
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// }, delay);
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// } else {
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var channel = root.channels[channelId];
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channel.pitchBend = program;
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// }
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};
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midi.noteOn = function(channelId, noteId, velocity, delay) {
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delay = delay || 0;
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/// check whether the note exists
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var channel = root.channels[channelId];
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var instrument = channel.instrument;
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var bufferId = instrument + '' + noteId;
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var buffer = audioBuffers[bufferId];
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if (!buffer) {
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// console.log(MIDI.GM.byId[instrument].id, instrument, channelId);
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return;
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}
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/// convert relative delay to absolute delay
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if (delay < ctx.currentTime) {
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delay += ctx.currentTime;
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}
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/// create audio buffer
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if (useStreamingBuffer) {
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var source = ctx.createMediaElementSource(buffer);
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} else { // XMLHTTP buffer
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var source = ctx.createBufferSource();
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source.buffer = buffer;
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}
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/// add effects to buffer
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if (effects) {
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var chain = source;
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for (var key in effects) {
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chain.connect(effects[key].input);
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chain = effects[key];
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}
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}
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/// add gain + pitchShift
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var gain = (velocity / 127) * (masterVolume / 127) * 2 - 1;
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source.connect(ctx.destination);
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source.playbackRate.value = 1; // pitch shift
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source.gainNode = ctx.createGain(); // gain
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source.gainNode.connect(ctx.destination);
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source.gainNode.gain.value = Math.min(1.0, Math.max(-1.0, gain));
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source.connect(source.gainNode);
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///
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if (useStreamingBuffer) {
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if (delay) {
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return setTimeout(function() {
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buffer.currentTime = 0;
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buffer.play()
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}, delay * 1000);
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} else {
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buffer.currentTime = 0;
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buffer.play()
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}
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} else {
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source.start(delay || 0);
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}
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///
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sources[channelId + '' + noteId] = source;
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///
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return source;
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};
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midi.noteOff = function(channelId, noteId, delay) {
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delay = delay || 0;
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/// check whether the note exists
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var channel = root.channels[channelId];
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var instrument = channel.instrument;
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var bufferId = instrument + '' + noteId;
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var buffer = audioBuffers[bufferId];
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if (buffer) {
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if (delay < ctx.currentTime) {
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delay += ctx.currentTime;
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}
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///
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var source = sources[channelId + '' + noteId];
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if (source) {
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if (source.gainNode) {
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// @Miranet: 'the values of 0.2 and 0.3 could of course be used as
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// a 'release' parameter for ADSR like time settings.'
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// add { 'metadata': { release: 0.3 } } to soundfont files
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var gain = source.gainNode.gain;
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gain.linearRampToValueAtTime(gain.value, delay);
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gain.linearRampToValueAtTime(-1.0, delay + 0.3);
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}
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///
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if (useStreamingBuffer) {
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if (delay) {
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setTimeout(function() {
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buffer.pause();
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}, delay * 1000);
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} else {
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buffer.pause();
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}
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} else {
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if (source.noteOff) {
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source.noteOff(delay + 0.5);
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} else {
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source.stop(delay + 0.5);
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}
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}
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///
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delete sources[channelId + '' + noteId];
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///
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return source;
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}
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}
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};
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midi.chordOn = function(channel, chord, velocity, delay) {
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var res = {};
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for (var n = 0, note, len = chord.length; n < len; n++) {
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res[note = chord[n]] = midi.noteOn(channel, note, velocity, delay);
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}
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return res;
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};
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midi.chordOff = function(channel, chord, delay) {
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var res = {};
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for (var n = 0, note, len = chord.length; n < len; n++) {
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res[note = chord[n]] = midi.noteOff(channel, note, delay);
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}
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return res;
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};
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midi.stopAllNotes = function() {
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for (var sid in sources) {
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var delay = 0;
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if (delay < ctx.currentTime) {
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delay += ctx.currentTime;
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}
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var source = sources[sid];
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source.gain.linearRampToValueAtTime(1, delay);
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source.gain.linearRampToValueAtTime(0, delay + 0.3);
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if (source.noteOff) { // old api
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source.noteOff(delay + 0.3);
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} else { // new api
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source.stop(delay + 0.3);
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}
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delete sources[sid];
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}
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};
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midi.setEffects = function(list) {
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if (ctx.tunajs) {
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for (var n = 0; n < list.length; n ++) {
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var data = list[n];
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var effect = new ctx.tunajs[data.type](data);
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effect.connect(ctx.destination);
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effects[data.type] = effect;
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}
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} else {
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return console.log('Effects module not installed.');
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}
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};
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midi.connect = function(opts) {
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root.setDefaultPlugin(midi);
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midi.setContext(ctx || createAudioContext(), opts.onsuccess);
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};
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midi.getContext = function() {
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return ctx;
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};
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midi.setContext = function(newCtx, onload, onprogress, onerror) {
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ctx = newCtx;
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/// tuna.js effects module - https://github.com/Dinahmoe/tuna
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if (typeof Tuna !== 'undefined' && !ctx.tunajs) {
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ctx.tunajs = new Tuna(ctx);
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}
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/// loading audio files
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var urls = [];
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var notes = root.keyToNote;
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for (var key in notes) urls.push(key);
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///
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var waitForEnd = function(instrument) {
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for (var key in bufferPending) { // has pending items
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if (bufferPending[key]) return;
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}
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///
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if (onload) { // run onload once
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onload();
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onload = null;
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}
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};
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///
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var requestAudio = function(soundfont, instrumentId, index, key) {
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var url = soundfont[key];
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if (url) {
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bufferPending[instrumentId] ++;
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loadAudio(url, function(buffer) {
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buffer.id = key;
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var noteId = root.keyToNote[key];
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audioBuffers[instrumentId + '' + noteId] = buffer;
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///
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if (-- bufferPending[instrumentId] === 0) {
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var percent = index / 87;
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// console.log(MIDI.GM.byId[instrumentId], 'processing: ', percent);
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soundfont.isLoaded = true;
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waitForEnd(instrument);
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}
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}, function(err) {
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// console.log(err);
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});
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}
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};
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///
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var bufferPending = {};
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for (var instrument in root.Soundfont) {
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var soundfont = root.Soundfont[instrument];
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if (soundfont.isLoaded) {
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continue;
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}
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///
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var synth = root.GM.byName[instrument];
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var instrumentId = synth.number;
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///
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bufferPending[instrumentId] = 0;
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///
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for (var index = 0; index < urls.length; index++) {
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var key = urls[index];
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requestAudio(soundfont, instrumentId, index, key);
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}
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}
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///
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setTimeout(waitForEnd, 1);
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};
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/* Load audio file: streaming | base64 | arraybuffer
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---------------------------------------------------------------------- */
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function loadAudio(url, onload, onerror) {
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if (useStreamingBuffer) {
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var audio = new Audio();
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audio.src = url;
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audio.controls = false;
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audio.autoplay = false;
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audio.preload = false;
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audio.addEventListener('canplay', function() {
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onload && onload(audio);
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});
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audio.addEventListener('error', function(err) {
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onerror && onerror(err);
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});
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document.body.appendChild(audio);
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} else if (url.indexOf('data:audio') === 0) { // Base64 string
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var base64 = url.split(',')[1];
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var buffer = Base64Binary.decodeArrayBuffer(base64);
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ctx.decodeAudioData(buffer, onload, onerror);
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} else { // XMLHTTP buffer
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var request = new XMLHttpRequest();
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request.open('GET', url, true);
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request.responseType = 'arraybuffer';
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request.onload = function() {
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ctx.decodeAudioData(request.response, onload, onerror);
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};
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request.send();
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}
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};
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function createAudioContext() {
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return new (window.AudioContext || window.webkitAudioContext)();
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};
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})();
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})(MIDI); |