jsfx.js

(function(jsfx){
	'use strict';

	var chr = String.fromCharCode;
	var TAU = +Math.PI*2;
	var bitsPerSample = 16|0;
	var numChannels = 1|0;
	var sin = Math.sin;
	var pow = Math.pow;
	var abs = Math.abs;
	var EPSILON = 0.000001;

	jsfx.SampleRate = 0|0;
	jsfx.Sec = 0|0;

	jsfx.SetSampleRate = function(sampleRate){
		jsfx.SampleRate = sampleRate|0;
		jsfx.Sec = sampleRate|0;
	};
	jsfx.SetSampleRate(getDefaultSampleRate());

	// MAIN API

	// Creates a new Audio object based on the params
	// params can be a params generating function or the actual parameters
	jsfx.Sound = function(params){
		var processor = new Processor(params, jsfx.DefaultModules);
		var block = createFloatArray(processor.getSamplesLeft());
		processor.generate(block);
		return CreateAudio(block);
	};

	// Same as Sounds, but avoids locking the browser for too long
	// in case you have a large amount of sounds to generate
	jsfx.Sounds = function(library, ondone, onprogress){
		var audio  = {};
		var player = {};
		player._audio = audio;

		var toLoad = [];

		// create playing functions
		map_object(library, function(_, name){
			player[name] = function(){
				if(typeof audio[name] !== "undefined"){
					audio[name].currentTime = 0.0;
					audio[name].play();
				}
			};
			toLoad.push(name);
		});

		var loaded = 0, total = toLoad.length;
		function next(){
			if(toLoad.length == 0){
				ondone && ondone(sounds);
				return;
			}
			var name = toLoad.shift();
			audio[name] = jsfx.Sound(library[name]);
			loaded++;
			onprogress && onprogress(name, loaded, total);

			window.setTimeout(next, 30);
		}
		next();

		return player;
	}

	// SoundsImmediate takes a named set of params, and generates multiple
	// sound objects at once.
	jsfx.SoundsImmediate = function(library){
		var audio = {};
		var player = {};
		player._audio = audio;
		map_object(library, function(params, name){
			audio[name] = jsfx.Sound(params);
			player[name] = function(){
				if(typeof audio[name] !== "undefined"){
					audio[name].currentTime = 0.0;
					audio[name].play();
				}
			};
		})
		return player;
	};

	if(typeof AudioContext !== "undefined"){
		// Node creates a new AudioContext ScriptProcessor that outputs the
		// sound. It will automatically disconnect, unless otherwise specified.
		jsfx.Node = function(audioContext, params, modules, bufferSize, stayConnected){
			var node = audioContext.createScriptProcessor(bufferSize, 0, 1);
			var gen = new Processor(params, modules || jsfx.DefaultModules);
			node.onaudioprocess = function(ev){
				var block = ev.outputBuffer.getChannelData(0);
				gen.generate(block);
				if(!stayConnected && gen.finished){
					// we need to do an async disconnect, otherwise Chrome may
					// glitch
					setTimeout(function(){ node.disconnect(); }, 30);
				}
			}
			return node;
		}

		// Live creates an managed AudioContext for playing.
		// This is useful, when you want to use procedurally generated sounds.
		jsfx.Live = function(library, modules, BufferSize){
			//TODO: add limit for number of notes played at the same time
			BufferSize = BufferSize || 2048;
			var player = {};

			var context = new AudioContext();
			var volume = context.createGain();
			volume.connect(context.destination);

			player._context = context;
			player._volume = volume;

			map_object(library, function(params, name){
				player[name] =  function(){
					var node = jsfx.Node(context, params, modules, BufferSize);
					node.connect(volume);
				};
			});

			player._close = function(){
				context.close();
			};

			player._play = function(params){
				var node = jsfx.Node(context, params, modules, BufferSize);
				node.connect(volume);
			};

			return player;
		}
	} else {
		jsfx.Live = jsfx.Sounds;
	}

	// SOUND GENERATION
	jsfx.Module = {};

	// generators
	jsfx.G = {};

	var stage = jsfx.stage = {
		PhaseSpeed    : 0,
		PhaseSpeedMod : 10,
		Generator     : 20,
		SampleMod     : 30,
		Volume        : 40
	};
	function byStage(a,b){ return a.stage - b.stage; }

	jsfx.InitDefaultParams = InitDefaultParams;
	function InitDefaultParams(params, modules){
		// setup modules
		for(var i = 0; i < modules.length; i += 1){
			var M = modules[i];
			var P = params[M.name] || {};

			// add missing parameters
			map_object(M.params, function(def, name){
				if(typeof P[name] === 'undefined'){
					P[name] = def.D;
				}
			});

			params[M.name] = P;
		}
	}

	// Generates a stateful sound effect processor
	// params can be a function that creates a parameter set
	jsfx.Processor = Processor;
	function Processor(params, modules){
		params = params || {};
		modules = modules || jsfx.DefaultModules;

		if(typeof params === 'function'){
			params = params();
		} else {
			params = JSON.parse(JSON.stringify(params))
		}
		this.finished = false;

		this.state = {
			SampleRate: params.SampleRate || jsfx.SampleRate
		};

		// sort modules
		modules = modules.slice();
		modules.sort(byStage)
		this.modules = modules;

		// init missing params
		InitDefaultParams(params, modules);

		// setup modules
		for(var i = 0; i < this.modules.length; i += 1){
			var M = this.modules[i];
			this.modules[i].setup(this.state, params[M.name]);
		}
	}
	Processor.prototype = {
		//TODO: see whether this can be converted to a module
		generate: function(block){
			for(var i = 0|0; i < block.length; i += 1){
				block[i] = 0;
			}
			if(this.finished){ return; }

			var $ = this.state,
				N = block.length|0;
			for(var i = 0; i < this.modules.length; i += 1){
				var M = this.modules[i];
				var n = M.process($, block.subarray(0,N))|0;
				N = Math.min(N, n);
			}
			if(N < block.length){
				this.finished = true;
			}
			for(var i = N; i < block.length; i++){
				block[i] = 0;
			}
		},
		getSamplesLeft: function(){
			var samples = 0;
			for(var i = 0; i < this.state.envelopes.length; i += 1){
				samples += this.state.envelopes[i].N;
			}
			if(samples === 0){
				samples = 3*this.state.SampleRate;
			}
			return samples;
		}
	};

	// Frequency
	jsfx.Module.Frequency = {
		name: 'Frequency',
		params: {
			Start: { L:30, H:1800, D:440  },

			Min: { L:30, H:1800, D:30    },
			Max: { L:30, H:1800, D:1800  },

			Slide:      { L:-1, H:1, D:0 },
			DeltaSlide: { L:-1, H:1, D:0 },

			RepeatSpeed:  { L:0, H: 3.0, D: 0 },

			ChangeAmount: { L:-12, H:12, D:0 },
			ChangeSpeed : { L:  0, H:1,  D:0 }
		},
		stage: stage.PhaseSpeed,
		setup: function($, P){
			var SR = $.SampleRate;

			$.phaseParams = P;

			$.phaseSpeed    = P.Start * TAU / SR;
			$.phaseSpeedMax = P.Max * TAU / SR;
			$.phaseSpeedMin = P.Min * TAU / SR;

			$.phaseSpeedMin = Math.min($.phaseSpeedMin, $.phaseSpeed);
			$.phaseSpeedMax = Math.max($.phaseSpeedMax, $.phaseSpeed);

			$.phaseSlide = 1.0 + pow(P.Slide, 3.0) * 64.0 / SR;
			$.phaseDeltaSlide = pow(P.DeltaSlide, 3.0) / (SR * 1000);

			$.repeatTime = 0;
			$.repeatLimit = Infinity;
			if(P.RepeatSpeed > 0){
				$.repeatLimit = P.RepeatSpeed * SR;
			}

			$.arpeggiatorTime = 0;
			$.arpeggiatorLimit = P.ChangeSpeed * SR;
			if(P.ChangeAmount == 0){
				$.arpeggiatorLimit = Infinity;
			}
			$.arpeggiatorMod = 1 + P.ChangeAmount / 12.0;
		},
		process: function($, block){
			var speed = +$.phaseSpeed,
				min   = +$.phaseSpeedMin,
				max   = +$.phaseSpeedMax,
				slide = +$.phaseSlide,
				deltaSlide = +$.phaseDeltaSlide;

			var repeatTime  = $.repeatTime,
				repeatLimit = $.repeatLimit;

			var arpTime  = $.arpeggiatorTime,
				arpLimit = $.arpeggiatorLimit,
				arpMod   = $.arpeggiatorMod;

			for(var i = 0; i < block.length; i++){
				slide += deltaSlide;
				speed *= slide;
				speed = speed < min ? min : speed > max ? max : speed;

				if(repeatTime > repeatLimit){
					this.setup($, $.phaseParams);
					return i + this.process($, block.subarray(i)) - 1;
				}
				repeatTime++;

				if(arpTime > arpLimit){
					speed *= arpMod;
					arpTime = 0;
					arpLimit = Infinity;
				}
				arpTime++;

				block[i] += speed;
			}

			$.repeatTime = repeatTime;
			$.arpeggiatorTime = arpTime;
			$.arpeggiatorLimit = arpLimit;

			$.phaseSpeed = speed;
			$.phaseSlide = slide;

			return block.length;
		}
	};

	// Vibrato
	jsfx.Module.Vibrato = {
		name: 'Vibrato',
		params: {
			Depth:      {L: 0, H:1, D:0},
			DepthSlide: {L:-1, H:1, D:0},

			Frequency:      {L:  0.01, H:48, D:0},
			FrequencySlide: {L: -1.00, H: 1, D:0}
		},
		stage: stage.PhaseSpeedMod,
		setup: function($, P){
			var SR = $.SampleRate;
			$.vibratoPhase = 0;
			$.vibratoDepth = P.Depth;
			$.vibratoPhaseSpeed = P.Frequency * TAU / SR;

			$.vibratoPhaseSpeedSlide = 1.0 + pow(P.FrequencySlide, 3.0) * 3.0 / SR;
			$.vibratoDepthSlide = P.DepthSlide / SR;
		},
		process: function($, block){
			var phase = +$.vibratoPhase,
				depth = +$.vibratoDepth,
				speed = +$.vibratoPhaseSpeed,
				slide = +$.vibratoPhaseSpeedSlide,
				depthSlide = +$.vibratoDepthSlide;

			if((depth == 0) && (depthSlide <= 0)){
				return block.length;
			}

			for(var i = 0; i < block.length; i++){
				phase += speed;
				if(phase > TAU){phase -= TAU};
				block[i] += block[i] * sin(phase) * depth;

				speed *= slide;
				depth += depthSlide;
				depth = clamp1(depth);
			}

			$.vibratoPhase = phase;
			$.vibratoDepth = depth;
			$.vibratoPhaseSpeed = speed;
			return block.length;
		}
	};

	// Generator
	jsfx.Module.Generator = {
		name: 'Generator',
		params: {
			// C = choose
			Func: {C: jsfx.G, D:'square'},

			A: {L: 0, H: 1, D: 0},
			B: {L: 0, H: 1, D: 0},

			ASlide: {L: -1, H: 1, D: 0},
			BSlide: {L: -1, H: 1, D: 0}
		},
		stage: stage.Generator,
		setup: function($, P){
			$.generatorPhase = 0;

			if(typeof P.Func === 'string'){
				$.generator = jsfx.G[P.Func];
			} else {
				$.generator = P.Func;
			}
			if(typeof $.generator === 'object'){
				$.generator = $.generator.create();
			}
			assert(typeof $.generator === 'function', 'generator must be a function')

			$.generatorA = P.A;
			$.generatorASlide = P.ASlide;
			$.generatorB = P.B;
			$.generatorBSlide = P.BSlide;
		},
		process: function($, block){
			return $.generator($, block);
		}
	};

	// Karplus Strong algorithm for string sound
	var GuitarBufferSize = 1 << 16;
	jsfx.Module.Guitar = {
		name: 'Guitar',
		params: {
			A: {L:0.0, H:1.0, D: 1},
			B: {L:0.0, H:1.0, D: 1},
			C: {L:0.0, H:1.0, D: 1},
		},
		stage: stage.Generator,
		setup: function($, P){
			$.guitarA = P.A;
			$.guitarB = P.B;
			$.guitarC = P.C;

			$.guitarBuffer = createFloatArray(GuitarBufferSize);
			$.guitarHead = 0;
			var B = $.guitarBuffer;
			for(var i = 0; i < B.length; i++){
				B[i] = Math.random()*2 - 1;
			}
		},
		process: function($, block){
			var BS = GuitarBufferSize,
				BM = BS - 1;

			var A = +$.guitarA, B = +$.guitarB, C = +$.guitarC;
			var T = A + B + C;
			var h = $.guitarHead;

			var buffer = $.guitarBuffer;
			for(var i = 0; i < block.length; i++){
				// buffer size
				var n = (TAU / block[i])|0;
				n = n > BS ? BS : n;

				// tail
				var t = ((h - n) + BS) & BM;
				buffer[h] =
					(buffer[(t-0+BS)&BM]*A +
					 buffer[(t-1+BS)&BM]*B +
					 buffer[(t-2+BS)&BM]*C) / T;

				block[i] = buffer[h];
				h = (h + 1) & BM;
			}

			$.guitarHead = h;
			return block.length;
		}
	}

	// Low/High-Pass Filter
	jsfx.Module.Filter = {
		name: 'Filter',
		params: {
			LP:          {L: 0, H:1, D:1},
			LPSlide:     {L:-1, H:1, D:0},
			LPResonance: {L: 0, H:1, D:0},
			HP:          {L: 0, H:1, D:0},
			HPSlide:     {L:-1, H:1, D:0}
		},
		stage: stage.SampleMod + 0,
		setup: function($, P){
			$.FilterEnabled = (P.HP > EPSILON) || (P.LP < 1 - EPSILON);

			$.LPEnabled = P.LP < 1 - EPSILON;
			$.LP = pow(P.LP, 3.0) / 10;
			$.LPSlide = 1.0 + P.LPSlide * 100 / $.SampleRate;
			$.LPPos = 0;
			$.LPPosSlide = 0;

			$.LPDamping = 5.0 / (1.0 + pow(P.LPResonance, 2) * 20) * (0.01 + P.LP);
			$.LPDamping = 1.0 - Math.min($.LPDamping, 0.8);

			$.HP = pow(P.HP, 2.0) / 10;
			$.HPPos = 0;
			$.HPSlide = 1.0 + P.HPSlide * 100 / $.SampleRate;
		},
		enabled: function($){
			return $.FilterEnabled;
		},
		process: function($, block){
			if(!this.enabled($)){ return block.length; }

			var lp         = +$.LP;
			var lpPos      = +$.LPPos;
			var lpPosSlide = +$.LPPosSlide;
			var lpSlide    = +$.LPSlide;
			var lpDamping  = +$.LPDamping;
			var lpEnabled  = +$.LPEnabled;

			var hp      = +$.HP;
			var hpPos   = +$.HPPos;
			var hpSlide = +$.HPSlide;

			for(var i = 0; i < block.length; i++){
				if((hp > EPSILON) || (hp < -EPSILON)){
					hp *= hpSlide;
					hp = hp < EPSILON ? EPSILON: hp > 0.1 ? 0.1 : hp;
				}

				var lpPos_ = lpPos;

				lp *= lpSlide;
				lp = lp < 0 ? lp = 0 : lp > 0.1 ? 0.1 : lp;

				var sample = block[i];
				if(lpEnabled){
					lpPosSlide += (sample - lpPos) * lp;
					lpPosSlide *= lpDamping;
				} else {
					lpPos = sample;
					lpPosSlide = 0;
				}
				lpPos += lpPosSlide;

				hpPos += lpPos - lpPos_;
				hpPos *= 1.0 - hp;

				block[i] = hpPos;
			}

			$.LPPos = lpPos;
			$.LPPosSlide = lpPosSlide;
			$.LP = lp;
			$.HP = hp;
			$.HPPos = hpPos;

			return block.length;
		}
	};

	// Phaser Effect
	var PhaserBufferSize = 1 << 10;
	jsfx.Module.Phaser = {
		name: 'Phaser',
		params: {
			Offset: {L:-1, H:1, D:0},
			Sweep:  {L:-1, H:1, D:0}
		},
		stage: stage.SampleMod + 1,
		setup: function($, P){
			$.phaserBuffer = createFloatArray(PhaserBufferSize);
			$.phaserPos  = 0;
			$.phaserOffset = pow(P.Offset, 2.0) * (PhaserBufferSize - 4);
			$.phaserOffsetSlide = pow(P.Sweep, 3.0) * 4000 / $.SampleRate;
		},
		enabled: function($){
			return (abs($.phaserOffsetSlide) > EPSILON) ||
				(abs($.phaserOffset) > EPSILON);
		},
		process: function($, block){
			if(!this.enabled($)){ return block.length; }

			var BS = PhaserBufferSize,
				BM = BS - 1;

			var buffer = $.phaserBuffer,
				pos    = $.phaserPos|0,
				offset = +$.phaserOffset,
				offsetSlide = +$.phaserOffsetSlide;

			for(var i = 0; i < block.length; i++){
				offset += offsetSlide;
				//TODO: check whether this is correct
				if(offset < 0){
					offset = -offset;
					offsetSlide = -offsetSlide;
				}
				if(offset > BM){
					offset = BM;
					offsetSlide = 0;
				}

				buffer[pos] = block[i];
				var p = (pos - (offset|0) + BS) & BM;
				block[i] += buffer[p];

				pos = ((pos + 1) & BM)|0;
			}

			$.phaserPos = pos;
			$.phaserOffset = offset;
			return block.length;
		}
	};

	// Volume dynamic control with Attack-Sustain-Decay
	//   ATTACK  | 0              - Volume + Punch
	//   SUSTAIN | Volume + Punch - Volume
	//   DECAY   | Volume         - 0
	jsfx.Module.Volume = {
		name: 'Volume',
		params: {
			Master:  { L: 0, H: 1, D: 0.5 },
			Attack:  { L: 0.001, H: 1, D: 0.01 },
			Sustain: { L: 0, H: 2, D: 0.3 },
			Punch:   { L: 0, H: 3, D: 1.0 },
			Decay:   { L: 0.001, H: 2, D: 1.0 }
		},
		stage: stage.Volume,
		setup: function($, P){
			var SR = $.SampleRate;
			var V = P.Master;
			var VP = V * (1 + P.Punch);
			$.envelopes = [
				// S = start volume, E = end volume, N = duration in samples
				{S: 0, E: V, N: (P.Attack  * SR)|0 }, // Attack
				{S:VP, E: V, N: (P.Sustain * SR)|0 }, // Sustain
				{S: V, E: 0, N: (P.Decay   * SR)|0 }  // Decay
			];
			// G = volume gradient
			for(var i = 0; i < $.envelopes.length; i += 1){
				var e = $.envelopes[i];
				e.G = (e.E - e.S) / e.N;
			}
		},
		process: function($, block){
			var i = 0;
			while(($.envelopes.length > 0) && (i < block.length)){
				var E = $.envelopes[0];
				var vol = E.S,
					grad = E.G;

				var N = Math.min(block.length - i, E.N)|0;
				var end = (i+N)|0;
				for(; i < end; i += 1){
					block[i] *= vol;
					vol += grad;
					vol = clamp(vol, 0, 10);
				}
				E.S = vol;
				E.N -= N;
				if(E.N <= 0){
					$.envelopes.shift();
				}
			}
			return i;
		}
	};

	// PRESETS

	jsfx.DefaultModules = [
		jsfx.Module.Frequency,
		jsfx.Module.Vibrato,
		jsfx.Module.Generator,
		jsfx.Module.Filter,
		jsfx.Module.Phaser,
		jsfx.Module.Volume
	];
	jsfx.DefaultModules.sort(byStage);

	jsfx.EmptyParams = EmptyParams;
	function EmptyParams(){
		return map_object(jsfx.Module, function(){ return {} });
	}

	jsfx._RemoveEmptyParams = RemoveEmptyParams;
	function RemoveEmptyParams(params){
		for(var name in params){
			if(Object_keys(params[name]).length == 0){
				delete params[name];
			}
		}
	};

	jsfx.Preset = {
		Reset: function(){
			return EmptyParams();
		},
		Coin: function(){
			var p = EmptyParams();
			p.Frequency.Start = runif(880, 660);
			p.Volume.Sustain = runif(0.1);
			p.Volume.Decay = runif(0.4, 0.1);
			p.Volume.Punch = runif(0.3, 0.3);
			if(runif() < 0.5){
				p.Frequency.ChangeSpeed = runif(0.15, 0.1);
				p.Frequency.ChangeAmount = runif(8, 4);
			}
			RemoveEmptyParams(p);
			return p;
		},
		Laser: function(){
			var p = EmptyParams();
			p.Generator.Func = rchoose(['square', 'saw', 'sine']);

			if(runif() < 0.33){
				p.Frequency.Start = runif(880, 440);
				p.Frequency.Min = runif(0.1);
				p.Frequency.Slide = runif(0.3, -0.8);
			} else {
				p.Frequency.Start = runif(1200, 440);
				p.Frequency.Min = p.Frequency.Start - runif(880, 440);
				if(p.Frequency.Min < 110){ p.Frequency.Min = 110; }
				p.Frequency.Slide = runif(0.3, -1);
			}

			if(runif() < 0.5){
				p.Generator.A = runif(0.5);
				p.Generator.ASlide = runif(0.2);
			} else {
				p.Generator.A = runif(0.5, 0.4);
				p.Generator.ASlide = runif(0.7);
			}

			p.Volume.Sustain = runif(0.2, 0.1);
			p.Volume.Decay   = runif(0.4);
			if(runif() < 0.5){
				p.Volume.Punch = runif(0.3);
			}
			if(runif() < 0.33){
				p.Phaser.Offset = runif(0.2);
				p.Phaser.Sweep = runif(0.2);
			}
			if(runif() < 0.5){
				p.Filter.HP = runif(0.3);
			}
			RemoveEmptyParams(p);
			return p;
		},
		Explosion: function(){
			var p = EmptyParams();
			p.Generator.Func = 'noise';
			if(runif() < 0.5){
				p.Frequency.Start = runif(440, 40);
				p.Frequency.Slide = runif(0.4, -0.1);
			} else {
				p.Frequency.Start = runif(1600, 220);
				p.Frequency.Slide = runif(-0.2, -0.2);
			}

			if(runif() < 0.2){ p.Frequency.Slide = 0; }
			if(runif() < 0.3){ p.Frequency.RepeatSpeed = runif(0.5, 0.3); }

			p.Volume.Sustain = runif(0.3, 0.1);
			p.Volume.Decay   = runif(0.5);
			p.Volume.Punch   = runif(0.6, 0.2);

			if(runif() < 0.5){
				p.Phaser.Offset = runif(0.9, -0.3);
				p.Phaser.Sweep  = runif(-0.3);
			}

			if(runif() < 0.33){
				p.Frequency.ChangeSpeed = runif(0.3, 0.6);
				p.Frequency.ChangeAmount = runif(24, -12);
			}
			RemoveEmptyParams(p);
			return p;
		},
		Powerup: function(){
			var p = EmptyParams();
			if(runif() < 0.5){
				p.Generator.Func = 'saw';
			} else {
				p.Generator.A = runif(0.6);
			}

			p.Frequency.Start = runif(220, 440);
			if(runif() < 0.5){
				p.Frequency.Slide = runif(0.5, 0.2);
				p.Frequency.RepeatSpeed = runif(0.4, 0.4);
			} else {
				p.Frequency.Slide = runif(0.2, 0.05);
				if(runif() < 0.5){
					p.Vibrato.Depth = runif(0.6, 0.1);
					p.Vibrato.Frequency = runif(30, 10);
				}
			}

			p.Volume.Sustain = runif(0.4);
			p.Volume.Decay = runif(0.4, 0.1);

			RemoveEmptyParams(p);
			return p;
		},
		Hit: function(){
			var p = EmptyParams();
			p.Generator.Func = rchoose(['square', 'saw', 'noise']);
			p.Generator.A = runif(0.6);
			p.Generator.ASlide = runif(1, -0.5);

			p.Frequency.Start = runif(880, 220);
			p.Frequency.Slide = -runif(0.4, 0.3);

			p.Volume.Sustain = runif(0.1);
			p.Volume.Decay = runif(0.2, 0.1);

			if(runif() < 0.5){
				p.Filter.HP = runif(0.3);
			}

			RemoveEmptyParams(p);
			return p;
		},
		Jump: function(){
			var p = EmptyParams();
			p.Generator.Func = 'square';
			p.Generator.A = runif(0.6);

			p.Frequency.Start = runif(330, 330);
			p.Frequency.Slide = runif(0.4, 0.2);

			p.Volume.Sustain = runif(0.3, 0.1);
			p.Volume.Decay = runif(0.2, 0.1);

			if(runif() < 0.5){
				p.Filter.HP = runif(0.3);
			}
			if(runif() < 0.3){
				p.Filter.LP = runif(-0.6, 1);
			}

			RemoveEmptyParams(p);
			return p;
		},
		Select: function(){
			var p = EmptyParams();
			p.Generator.Func = rchoose(['square', 'saw']);
			p.Generator.A = runif(0.6);

			p.Frequency.Start = runif(660, 220);

			p.Volume.Sustain = runif(0.1, 0.1);
			p.Volume.Decay   = runif(0.2);

			p.Filter.HP = 0.2;
			RemoveEmptyParams(p);
			return p;
		},
		Lucky: function(){
			var p = EmptyParams();
			map_object(p, function(out, moduleName){
				var defs = jsfx.Module[moduleName].params;
				map_object(defs, function(def, name){
					if(def.C){
						var values = Object_keys(def.C);
						out[name] = values[(values.length * Math.random()) | 0];
					} else {
						out[name] = Math.random() * (def.H - def.L) + def.L;
					}
				});
			});
			p.Volume.Master = 0.4;
			p.Filter = {}; // disable filter, as it usually will clip everything
			RemoveEmptyParams(p);
			return p;
		}
	};

	// GENERATORS

	// uniform noise
	jsfx.G.unoise = newGenerator("sample = Math.random();");
	// sine wave
	jsfx.G.sine = newGenerator("sample = Math.sin(phase);");
	// saw wave
	jsfx.G.saw = newGenerator("sample = 2*(phase/TAU - ((phase/TAU + 0.5)|0));");
	// triangle wave
	jsfx.G.triangle = newGenerator("sample = Math.abs(4 * ((phase/TAU - 0.25)%1) - 2) - 1;");
	// square wave
	jsfx.G.square = newGenerator("var s = Math.sin(phase); sample = s > A ? 1.0 : s < A ? -1.0 : A;");
	// simple synth
	jsfx.G.synth = newGenerator("sample = Math.sin(phase) + .5*Math.sin(phase/2) + .3*Math.sin(phase/4);");

	// STATEFUL
	var __noiseLast = 0;
	jsfx.G.noise = newGenerator("if(phase % TAU < 4){__noiseLast = Math.random() * 2 - 1;} sample = __noiseLast;");

	// Karplus-Strong string
	jsfx.G.string = {
		create: function(){
			var BS = 1 << 16;
			var BM = BS-1;

			var buffer = createFloatArray(BS);
			for(var i = 0; i < buffer.length; i++){
				buffer[i] = Math.random()*2-1;
			}

			var head = 0;
			return function($, block){
				var TAU = Math.PI * 2;
				var A = +$.generatorA, ASlide = +$.generatorASlide,
					B = +$.generatorB, BSlide = +$.generatorBSlide;
				var buf = buffer;

				for(var i = 0; i < block.length; i++){
					var phaseSpeed = block[i];
					var n = (TAU/phaseSpeed)|0;
					A += ASlide; B += BSlide;
					A = A < 0 ? 0 : A > 1 ? 1 : A;
					B = B < 0 ? 0 : B > 1 ? 1 : B;

					var t = ((head - n) + BS) & BM;
					var sample = (
						buf[(t-0+BS)&BM]*1 +
						buf[(t-1+BS)&BM]*A +
						buf[(t-2+BS)&BM]*B) / (1+A+B);

					buf[head] = sample;
					block[i] = buf[head];
					head = (head + 1) & BM;
				}

				$.generatorA = A;
				$.generatorB = B;
				return block.length;
			}
		}
	};

	// Generates samples using given frequency and generator
	function newGenerator(line){
		return new Function("$", "block", "" +
			"var TAU = Math.PI * 2;\n" +
			"var sample;\n" +
			"var phase = +$.generatorPhase,\n"+
			"	A = +$.generatorA, ASlide = +$.generatorASlide,\n"+
			"	B = +$.generatorB, BSlide = +$.generatorBSlide;\n"+
			"\n"+
			"for(var i = 0; i < block.length; i++){\n"+
			"	var phaseSpeed = block[i];\n"+
			"	phase += phaseSpeed;\n"+
			"	if(phase > TAU){ phase -= TAU };\n"+
			"	A += ASlide; B += BSlide;\n"+
			"   A = A < 0 ? 0 : A > 1 ? 1 : A;\n"+
			"   B = B < 0 ? 0 : B > 1 ? 1 : B;\n"+
			line +
			"	block[i] = sample;\n"+
			"}\n"+
			"\n"+
			"$.generatorPhase = phase;\n"+
			"$.generatorA = A;\n"+
			"$.generatorB = B;\n"+
			"return block.length;\n" +
		"");
	}

	// WAVE SUPPORT

	// Creates an Audio element from audio data [-1.0 .. 1.0]
	jsfx.CreateAudio = CreateAudio;
	function CreateAudio(data){
		if(typeof Float32Array !== "undefined"){
			assert(data instanceof Float32Array, 'data must be an Float32Array');
		}

		var blockAlign = numChannels * bitsPerSample >> 3;
		var byteRate = jsfx.SampleRate * blockAlign;

		var output = createByteArray(8 + 36 + data.length * 2);
		var p = 0;

		// emits string to output
		function S(value){
			for(var i = 0; i < value.length; i += 1){
				output[p] = value.charCodeAt(i); p++;
			}
		}

		// emits integer value to output
		function V(value, nBytes){
			if(nBytes <= 0){ return; }
			output[p] = value & 0xFF; p++;
			V(value >> 8, nBytes - 1);
		}

		S('RIFF'); V(36 + data.length * 2, 4);

		S('WAVEfmt '); V(16, 4); V(1, 2);
		V(numChannels, 2); V(jsfx.SampleRate, 4);
		V(byteRate, 4); V(blockAlign, 2); V(bitsPerSample, 2);

		S('data'); V(data.length * 2, 4);
		CopyFToU8(output.subarray(p), data);

		return new Audio('data:audio/wav;base64,' + U8ToB64(output));
	};

	jsfx.DownloadAsFile = function(audio){
		assert(audio instanceof Audio, 'input must be an Audio object');
		document.location.href = audio.src;
	};

	// HELPERS
	jsfx.Util = {};

	// Copies array of Floats to a Uint8Array with 16bits per sample
	jsfx.Util.CopyFToU8 = CopyFToU8;
	function CopyFToU8(into, floats){
		assert(into.length/2 == floats.length,
			'the target buffer must be twice as large as the iinput');

		var k = 0;
		for(var i = 0; i < floats.length; i++){
			var v = +floats[i];
			var	a = (v * 0x7FFF)|0;
			a = a < -0x8000 ? -0x8000 : 0x7FFF < a ? 0x7FFF : a;
			a += a < 0 ? 0x10000 : 0;
			into[k] = a & 0xFF; k++;
			into[k] = a >> 8; k++;
		}
	}

	function U8ToB64(data){
		var CHUNK = 0x8000;
		var result = '';
		for(var start = 0; start < data.length; start += CHUNK){
			var end = Math.min(start + CHUNK, data.length);
			result += String.fromCharCode.apply(null, data.subarray(start, end));
		}
		return btoa(result);
	}

	// uses AudioContext sampleRate or 44100;
	function getDefaultSampleRate(){
		if(typeof AudioContext !== 'undefined'){
			return (new AudioContext()).sampleRate;
		}
		return 44100;
	}

	// for checking pre/post conditions
	function assert(condition, message){
		if(!condition){ throw new Error(message); }
	}

	function clamp(v, min, max){
		v = +v; min = +min; max = +max;
		if(v < min){ return +min; }
		if(v > max){ return +max; }
		return +v;
	}

	function clamp1(v){
		v = +v;
		if(v < +0.0){ return +0.0; }
		if(v > +1.0){ return +1.0; }
		return +v;
	}

	function map_object(obj, fn){
		var r = {};
		for(var name in obj){
			if(obj.hasOwnProperty(name)){
				r[name] = fn(obj[name], name);
			}
		}
		return r;
	}

	// uniform random
	function runif(scale, offset){
		var a = Math.random();
        if(scale !== undefined)
            a *= scale;
        if(offset !== undefined)
            a += offset;
        return a;
	}

	function rchoose(gens){
		return gens[(gens.length*Math.random())|0];
	}

	function Object_keys(obj){
		var r = [];
		for(var name in obj){ r.push(name); }
		return r;
	}

	jsfx._createFloatArray = createFloatArray;
	function createFloatArray(N){
		if(typeof Float32Array === "undefined") {
			var r = new Array(N);
			for(var i = 0; i < r.length; i++){
				r[i] = 0.0;
			}
		}
		return new Float32Array(N);
	}

	function createByteArray(N){
		if(typeof Uint8Array === "undefined") {
			var r = new Array(N);
			for(var i = 0; i < r.length; i++){
				r[i] = 0|0;
			}
		}
		return new Uint8Array(N);
	}
})(this.jsfx = {});