js.js

$(document).ready(function() {

	// create start sounds
	var data = [];
	$('<audio />').attr({id: 'el1', src: encodeAudio8bit(data)}).appendTo('#sounds1');
	$('<audio />').attr({id: 'el2', src: encodeAudio8bit(data)}).appendTo('#sounds2');

	var currentlyPlayingAudioThing = "el1";
	var notCurrentlyPlayingAudioThing = "el2";

	// loop em
	$('#el1').on('ended', function() { 
		currentlyPlayingAudioThing = 'el1';
		notCurrentlyPlayingAudioThing = 'el2';
		this.pause(); 
		this.currentTime = 0; 
		$('#el2')[0].play(); 
	});
	$('#el2').on('ended', function() { 
		currentlyPlayingAudioThing = 'el2';
		notCurrentlyPlayingAudioThing = 'el1'; 
		this.pause(); 
		this.currentTime = 0; 
		$('#el1')[0].play(); 
	});

	function playSound(freq) {
	  var data = [];
	  carrierWave(data, 10000, freq);
	//  applySinDistort(data, 2);
	 // applyEnvelope(data, 1, 2, 3, 4);
	  var encodedAudioUrl = encodeAudio8bit(data);
	  $('#el1')[0].pause();
	  $('#el2')[0].pause();
	  $('#el1').attr({src: encodedAudioUrl});
	  $('#el2').attr({src: encodedAudioUrl});  
	  $('#el1')[0].play();
	}

	var freqTable = {
		A: 261.626, 
		W: 277.183,
		S: 293.665,
		E: 311.127,
		D: 329.628,
		F: 349.228,
		T: 369.994,
		G: 391.995,
		Y: 415.305,
		H: 440.000,
		U: 466.164,
		J: 493.883,
		K: 523.251
	};

	$(document).keydown(function(ev) {
		var freq = freqTable[String.fromCharCode(ev.keyCode)];
		if (freq) {
			playSound(freq);
		}
	});

	$(document).keyup(function(ev) {
		$('#el1')[0].pause();
		$('#el2')[0].pause();
	});
});

var sampleRate = 1378.125;

function applyEnvelope(data, attack, decay, sustain, release) {
  var dataLength = data.length;
  attack *= dataLength;
  decay *= dataLength;
  release *= dataLength;
  var is = 1 - sustain;
  for (var i = 0; i < attack; ++i) {
    data[i] *= i / attack;
  }
  for (; i < (attack + decay); ++i) {
    data[i] *= (1 - (i - attack) / decay) * is + sustain;
  }
  for (; i < (dataLength - release); ++i) {
    data[i] *= sustain;
  }
  for (var j = i; i < dataLength; ++i) {
    data[i] *= sustain * (1 - (i - j) / release);
  }
}

function getFreqSweep(data, length, freq1, freq2) {
  var d1 = Math.PI * 2 * freq1 / sampleRate,
    d2 = Math.PI * 2 * freq2 / sampleRate,
    dd = (d2 - d1) / length,
    dt = d1,
    t = 0;
  for (var i = 0; i < length; ++i) {
    data[i] = Math.sin(t);
    t += dt;
    dt += dd;
  }
}

function carrierWave(data, length, freq) {
  var d1 = Math.PI * 2 * freq / sampleRate;
  for (var i = 0; i < length; ++i) {
    data[i] = Math.sin(i * d1);
  }
}

function encodeAudio8bit(data) {
  var n = data.length, i;

  // 8-bit mono WAVE header template
  var header = "RIFF<##>WAVEfmt \x10\x00\x00\x00\x01\x00\x01\x00<##><##>\x01\x00\x08\x00data<##>";

  // Helper to insert a 32-bit little endian int.
  function insertLong(value) {
    var bytes = "";
    for (i = 0; i < 4; ++i) {
        bytes += String.fromCharCode(value % 256);
        value = Math.floor(value / 256);
    }
    header = header.replace('<##>', bytes);
  }

  // ChunkSize
  insertLong(36 + n);

  // SampleRate
  insertLong(sampleRate);

  // ByteRate
  insertLong(sampleRate);

  // Subchunk2Size
  insertLong(n);

  // Output sound data
  for (var i = 0; i < n; ++i) {
    header += String.fromCharCode(Math.round(Math.min(1, Math.max(-1, data[i])) * 127 + 127));
  }

  return 'data:audio/wav;base64,' + btoa(header);
}

function applySinDistort(data, drive) {
  var n = data.length;
  var s = Math.PI * drive / 2;
  for (var i = 0; i < n; ++i) {
    data[i] = Math.sin(data[i] * s);
  }
}