scratch-vm/AudioEngine.js

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function AudioEngine () {
this.tone = new Tone();
// effects setup
this.delay = new Tone.FeedbackDelay(0.25, 0.5);
this.delay.wet.value = 0;
this.pitchShift = new Tone.PitchShift();
this.panner = new Tone.Panner();
this.reverb = new Tone.Freeverb();
this.reverb.wet.value = 0;
Tone.Master.chain(this.delay, this.pitchShift, this.panner, this.reverb);
// synth setup for play note block
this.synth = new Tone.PolySynth(6, Tone.Synth).toMaster();
// drum sounds
var drumFileNames = ['high_conga', 'small_cowbell', 'snare_drum', 'splash cymbal'];
this.drumSamplers = this._loadSoundFiles(drumFileNames);
// sound files
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var soundFileNames = ['meow','boing','cave','drip_drop','drum_machine','eggs','zoop'];
this.soundSamplers = this._loadSoundFiles(soundFileNames);
}
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AudioEngine.prototype.playSound = function (soundNum) {
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this.soundSamplers[soundNum].triggerAttack();
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};
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AudioEngine.prototype.getSoundDuration = function (soundNum) {
return this.soundSamplers[soundNum].player.buffer.duration;
};
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AudioEngine.prototype.playNoteForBeats = function(note, beats) {
var freq = this._midiToFreq(note);
this.synth.triggerAttackRelease(freq, beats);
};
AudioEngine.prototype.playDrumForBeats = function(drumNum, beats) {
this.drumSamplers[drumNum].triggerAttack();
};
AudioEngine.prototype.stopAllSounds = function() {
// stop synth notes
this.synth.releaseAll();
// stop drum notes
for (var i=0; i<this.drumSamplers.length; i++) {
this.drumSamplers[i].triggerRelease();
}
// stop sounds triggered with playSound
for (var i=0; i<this.soundSamplers.length; i++) {
this.soundSamplers[i].triggerRelease();
}
};
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AudioEngine.prototype.setEffect = function(effect, value) {
switch (effect) {
case 'ECHO':
this.delay.wet.value = (value / 100) / 2; // max 50% wet (need dry signal too)
break;
case 'PAN':
this.panner.pan.value = value / 100;
break;
case 'REVERB':
this.reverb.wet.value = value / 100;
break;
case 'PITCH':
this.pitchShift.pitch = value / 20; // arbitrary scaling of 20 per semitone, for now... default 100 is a perfect fourth
break;
}
}
AudioEngine.prototype.changeEffect = function(effect, value) {
switch (effect) {
case 'ECHO':
this.delay.wet.value += (value / 100) / 2; // max 50% wet (need dry signal too)
this.delay.wet.value = this._clamp(this.delay.wet.value, 0, 0.5);
break;
case 'PAN':
this.panner.pan.value += value / 100;
this.panner.pan.value = this._clamp(this.panner.pan.value, -1, 1);
break;
case 'REVERB':
this.reverb.wet.value += value / 100;
this.reverb.wet.value = this._clamp(this.reverb.wet.value, 0, 1);
break;
case 'PITCH':
this.pitchShift.pitch += value / 20;
break;
}
}
AudioEngine.prototype.clearEffects = function() {
this.delay.wet.value = 0;
this.panner.pan.value = 0;
this.reverb.wet.value = 0;
this.pitchShift.pitch = 0;
}
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AudioEngine.prototype._loadSoundFiles = function(filenames) {
var samplers = [];
for (var name of filenames) {
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var sampler = new Tone.Sampler('sounds/' + name + '.mp3').toMaster();
samplers.push(sampler);
}
return samplers;
};
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AudioEngine.prototype._midiToFreq = function(midiNote) {
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var freq = this.tone.intervalToFrequencyRatio(midiNote - 60) * 261.63; // 60 is C4
return freq;
};
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AudioEngine.prototype._clamp = function(input, min, max) {
return Math.min(Math.max(input, min), max);
};