sound.js

// Built from Mohit Cheppudira's sine wave generator - http://0xfe.blogspot.com
// Modified by Murat Ayfer - http://muratayfer.com
// Modified by Mika Kalathil
var ON = 450;
var OFF = 550;

var soundWave = function(context) {
  // xs is a list of x (time) values, one per wave.
  // time is not represented as synchronized clicks or milliseconds, its passing is freq dependent
  // so that's why we keep a value per each wave.
  this.frequency = 0;
  this.nextFrequency = 0
  this.xs = [];
  this.counter = 0;
  this.fadeout_counter = 0;
  this.context = context;
  this.sampleRate = this.context.sampleRate; // 44100 by default
  this.sampleRateMillisecond = this.sampleRate / 1000;
  this.node = context.createJavaScriptNode(1024, 1, 2)
  var self = this;
  this.node.onaudioprocess = function(e) { self.process(e) };
}

soundWave.prototype.process = function(e) {
  // Get a reference to the output buffer and fill it up.
  var channels = [ e.outputBuffer.getChannelData(0), e.outputBuffer.getChannelData(1) ];
  var data = e.outputBuffer.getChannelData(0);
  var buffer_size = channels[0].length;
  var num_channels = channels.length;
  var amplitude = 0;

  for (var i = 0; i < buffer_size; i++) {

      y = Math.sin((this.counter) * Math.PI * 2 * this.frequency / this.sampleRate)

      if(amplitude = 0) {
          amplitude = 1;
      } else {
          amplitude = 0;
      }


      for(var k = 0; k < num_channels; k++) {
          channels[k][i] = y;
      }
      this.counter += 1;
  }

  if(!this.playing) {
      // fadeout to prevent popping during a pause/stop
      var fadeoutLength = 2;
      this.frequency = 18800
      amplitude -= amplitude * (this.fadeoutCounter++/fadeoutLength)
      if(this.fadeout_counter >= fadeoutLength) {
          this.fadeout_counter = 0;
          this.node.disconnect(this.context.destination);
      }
  }

  // Frequency shift normalization
  if (this.nextFrequency != this.frequency) {
    // Figure out what the next point is.
    var nextData = this.amplitude * Math.sin(
      this.x / (this.sampleRate / (this.frequency * 2 * Math.PI)));

    // If the current point approximates 0, and the direction is positive,
    // switch frequencies.
    if (data[i] < 0.001 && data[i] > -0.001 && data[i] < nextData) {
      this.frequency = this.nextFrequency;
      this.x = 0;
    }
  }
}

soundWave.prototype.play = function() {
  this.node.connect(this.context.destination)
  this.playing = true
}

soundWave.prototype.stop = function() {
  this.playing = false
}

soundWave.prototype.changeFrequency = function(value) {
  this.nextFrequency = value
}


var BinaryConversion = {
  toString: function(binary) {
    return binary.replace(/\s*[01]{8}\s*/g, function(binary) {
      return String.fromCharCode(parseInt(binary, 2))
    })
  },
  toBinary: function(string, spaceSeparatedOctets) {
    return string.replace(/[\s\S]/g, function(string) {
      string = BinaryConversion.removeSpaces(string.charCodeAt().toString(2))
      return !1 == spaceSeparatedOctets ? string : string + " "
    })
  },
  removeSpaces: function(number) {
    return "00000000".slice(String(number).length) + number
  }
}