88 lines
3.6 KiB
JavaScript
88 lines
3.6 KiB
JavaScript
/////////////////////// BlueAudio 1.0.4 \\\\\\\\\\\\\\\\\\\\\\\\\\
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// This requires BlueCore in order to run and assumes it is \\
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// already loaded. It will not work without BlueCore loaded \\
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// first. \\
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//////////////////////////////////\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\
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function getFrequency (note, octave) {
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// octaves double value
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// half steps are calculated using fn = f0*(2^(1/12))^n
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var base = 16.35; // bottom c
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var a = Math.pow(2,1/12); // Defining a
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// Check our inputs for sanity
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if ("number" != typeof note) { note = 1; }
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if ("number" != typeof octave) { octave = 4; }
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if (note < 0) { note = 0;}
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if (note > 11) { note = 11; }
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if (octave < 0) { octave = 0; }
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if (octave > 8) { octave = 8; }
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return (base*Math.pow(a,note))*Math.pow(2,octave);
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}
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function parseNote (string) {
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if ("string" != typeof string) { string = "4c1/4"; }
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var noteReg = new RegExp(/^([1-8])([a-g][nb#]?)(\d)\/(\d{1,2})/i);
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var noteArray = string.match(noteReg);
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if (noteArray) { if (noteArray.length == 5) {
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var noteTranslationObject = {"cb":11,"cn":0,"c":0,"c#":1,"db":1,"dn":2,"d":2,"d#":3,"eb":3,"en":4,"e":4,"e#":5,"fb":4,"fn":5,"f":5,"f#":6,"gb":6,"gn":7,"g":7,"g#":8,"ab":8,"an":9,"a":9,"a#":10,"bb":10,"bn":11,"b":11,"b#":0};
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var octave = noteArray[1]-0;
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var length = (noteArray[3]/noteArray[4]);
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var step = noteTranslationObject[noteArray[2]];
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if ("cb" == noteArray[2]) { octave--; }
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if ("b#" == noteArray[2]) { octave++; }
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return {"note":step,"octave":octave,"length":length};
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} else {
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console.log("bad note: "+noteArray.join(" "));
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return {};
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}} else {
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console.log("bad note");
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return {};
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}
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}
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function parseSequence (string) {
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if ("string" != typeof string) { string = "4c1/4;"; }
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var notes = string.split(";");
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var sequence = [];
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notes.forEach( function (note) {
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sequence.push( parseNote(note) );
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});
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return sequence;
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}
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function playNote (soundObject, note, octave, length, wave, delay) {
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if ("string" != typeof wave) { wave = "sine"; }
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if ("number" != typeof length) { length = 1; }
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if ("number" != typeof octave) { octave = 4; }
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if ("number" != typeof note) { note = 0; }
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if ("object" != typeof soundObject) { soundObject = new AudioContext(); }
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if ("number" != typeof delay) { delay = 0; }
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var waveform = soundObject.createOscillator();
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var gain = soundObject.createGain();
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waveform.connect(gain);
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gain.connect(soundObject.destination);
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waveform.type = wave;
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waveform.frequency.setValueAtTime(getFrequency(note,octave), 0);
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gain.gain.setValueAtTime(1, soundObject.currentTime+delay);
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waveform.start(soundObject.currentTime+delay);
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gain.gain.exponentialRampToValueAtTime(0.00001,soundObject.currentTime+length+delay);
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waveform.stop(soundObject.currentTime+(length*1.5)+delay);
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}
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function playSequence (soundObject, sequenceArray, defaultWave, tempo) {
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if ("object" != typeof soundObject) { soundObject = new AudioContext(); }
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if ("string" != typeof defaultWave) { defaultWave = "sine"; }
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if ("sine" != defaultWave && "square" != defaultWave && "triangle" != defaultWave && "sawtooth" != defaultWave) { defaultWave = "sine"; }
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if ("number" != typeof tempo) { tempo = 60; }
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if (0 >= tempo) { tempo = 1; }
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if ("object" != typeof sequenceArray) { sequenceArray = [{"note":0,"octave":4,"length":1,"type":"sine"}]; }
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var timing = 0;
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sequenceArray.forEach( function (thisNote) {
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var adjustedLength = (thisNote.length*(60/tempo))*4;
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if ("undefined" == typeof thisNote.type) { thisNote.type = defaultWave; }
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playNote(soundObject, thisNote.note, thisNote.octave, adjustedLength, thisNote.type, timing);
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timing += adjustedLength/4;
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});
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}
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