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/*
----------------------------------------------------------------------
AudioTag <audio> - OGG or MPEG Soundbank
----------------------------------------------------------------------
http://dev.w3.org/html5/spec/Overview.html#the-audio-element
----------------------------------------------------------------------
*/
(function(root) { 'use strict';
window.Audio && (function() {
var midi = root.AudioTag = { api: 'audiotag' };
var noteToKey = {};
var volume = 127; // floating point
var buffer_nid = -1; // current channel
var audioBuffers = []; // the audio channels
var notesOn = []; // instrumentId + noteId that is currently playing in each 'channel', for routing noteOff/chordOff calls
var notes = {}; // the piano keys
for (var nid = 0; nid < 12; nid ++) {
audioBuffers[nid] = new Audio();
}
var playChannel = function(channel, note) {
if (!root.channels[channel]) return;
var instrument = root.channels[channel].instrument;
var instrumentId = root.GM.byId[instrument].id;
var note = notes[note];
if (note) {
var instrumentNoteId = instrumentId + '' + note.id;
var nid = (buffer_nid + 1) % audioBuffers.length;
var audio = audioBuffers[nid];
notesOn[ nid ] = instrumentNoteId;
if (!root.Soundfont[instrumentId]) {
if (root.DEBUG) {
console.log('404', instrumentId);
}
return;
}
audio.src = root.Soundfont[instrumentId][note.id];
audio.volume = volume / 127;
audio.play();
buffer_nid = nid;
}
};
var stopChannel = function(channel, note) {
if (!root.channels[channel]) return;
var instrument = root.channels[channel].instrument;
var instrumentId = root.GM.byId[instrument].id;
var note = notes[note];
if (note) {
var instrumentNoteId = instrumentId + '' + note.id;
for (var i = 0, len = audioBuffers.length; i < len; i++) {
var nid = (i + buffer_nid + 1) % len;
var cId = notesOn[nid];
if (cId && cId == instrumentNoteId) {
audioBuffers[nid].pause();
notesOn[nid] = null;
return;
}
}
}
};
midi.audioBuffers = audioBuffers;
midi.send = function(data, delay) { };
midi.setController = function(channel, type, value, delay) { };
midi.setVolume = function(channel, n) {
volume = n; //- should be channel specific volume
};
midi.programChange = function(channel, program) {
root.channels[channel].instrument = program;
};
midi.pitchBend = function(channel, program, delay) { };
midi.noteOn = function(channel, note, velocity, delay) {
var id = noteToKey[note];
if (!notes[id]) return;
if (delay) {
return setTimeout(function() {
playChannel(channel, id);
}, delay * 1000);
} else {
playChannel(channel, id);
}
};
midi.noteOff = function(channel, note, delay) {
// var id = noteToKey[note];
// if (!notes[id]) return;
// if (delay) {
// return setTimeout(function() {
// stopChannel(channel, id);
// }, delay * 1000)
// } else {
// stopChannel(channel, id);
// }
};
midi.chordOn = function(channel, chord, velocity, delay) {
for (var idx = 0; idx < chord.length; idx ++) {
var n = chord[idx];
var id = noteToKey[n];
if (!notes[id]) continue;
if (delay) {
return setTimeout(function() {
playChannel(channel, id);
}, delay * 1000);
} else {
playChannel(channel, id);
}
}
};
midi.chordOff = function(channel, chord, delay) {
for (var idx = 0; idx < chord.length; idx ++) {
var n = chord[idx];
var id = noteToKey[n];
if (!notes[id]) continue;
if (delay) {
return setTimeout(function() {
stopChannel(channel, id);
}, delay * 1000);
} else {
stopChannel(channel, id);
}
}
};
midi.stopAllNotes = function() {
for (var nid = 0, length = audioBuffers.length; nid < length; nid++) {
audioBuffers[nid].pause();
}
};
midi.connect = function(opts) {
root.setDefaultPlugin(midi);
///
for (var key in root.keyToNote) {
noteToKey[root.keyToNote[key]] = key;
notes[key] = {id: key};
}
///
opts.onsuccess && opts.onsuccess();
};
})();
})(MIDI);
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