gistfile1.js

/*!
 * Cedric Van Goethem
 * Rudimentary Twinkle Twinkle Little Star demo for
 * http://wavepot.com/
 */
var transpose = 0.5;
var volume = 0.1;
var tempo = 2;

var notes = {'A': 440, 'B': 493.88, 'C': 523.25, 'D': 587.33, 'E': 659.25, 'F': 698.46, 'G': 783.99 };
var start = 0.0;
var pause = 0.1;
var pauseStart = 0;
var isPausing = false;
var i = 0;

var song = [['C', 0.5], ['C', 0.5], ['G', 0.5], ['G', 0.5], ['A2', 0.5], ['A2', 0.5], ['G', 1], 
  ['F1', 0.25], ['F1', 0.25], ['F1', 0.25], ['F1', 0.25], ['E', 0.5], ['E', 0.5], ['D', 0.5], ['D', 0.5], ['C', 1],
  ['G', 0.5], ['G', 0.5], ['F', 0.5], ['F', 0.5], ['E', 0.5], ['E', 0.5], ['D', 1],
  ['G', 0.5], ['G', 0.5], ['F', 0.5], ['F', 0.5], ['E', 0.5], ['E', 0.5], ['D', 1],
  ['C', 0.5], ['C', 0.5], ['G', 0.5], ['G', 0.5], ['A2', 0.5], ['A2', 0.5], ['G', 1],
  ['F1', 0.25], ['F1', 0.25], ['F1', 0.25], ['F1', 0.25], ['E', 0.5], ['E', 0.5], ['D', 0.5], ['D', 0.5], ['C', 1]];

function dsp(t) {
  
  if(isPausing){
    if(t - pauseStart >= pause / tempo){
      isPausing = false;
      start = t;
    }
  } else {
    if(t - start >= (song[i][1]/tempo)){
      i = (i + 1) % song.length;
      isPausing = true;
      pauseStart = t;
    }
    
    var noteString = song[i][0];
    var note = noteString[0];
    var xtraTranspose = noteString.length > 1 ? parseInt(noteString[1]) : 1;
    
    var freq = notes[note] * transpose * xtraTranspose;
    return volume * Math.sin(2 * Math.PI * t * freq);
  }
}