title: MediaElementAudioSource outputs zeroes due to CORS access restrictions for
body: <p>I try get frequency from element audio with src is a url</p>
  
  <pre><code>var aud = document.getElementById("audio-player"); 
  var canvas, ctx, source, context, analyser, fbc_array;
  function initMp3Player(){
  try {
    context = new (window.AudioContext || window.webkitAudioContext)();
  } catch(e) {
      throw new Error('The Web Audio API is unavailable');
  }
  
  analyser = context.createAnalyser(); // AnalyserNode method
  analyser.smoothingTimeConstant = 0.6;
  analyser.fftSize = 512;
  canvas = document.getElementById('canvas_up');
  
  ctx = canvas.getContext('2d');
  
  source = context.createMediaElementSource(aud); 
  
  source.crossOrigin = 'anonymous';
  source.connect(analyser);
  analyser.connect(context.destination);
  frameLooper();
  }
  
  function frameLooper(){
  window.requestAnimationFrame(frameLooper);
  fbc_array = new Uint8Array(analyser.frequencyBinCount);
  analyser.getByteFrequencyData(fbc_array);
  console.log(fbc_array);
  
  var gradient = ctx.createLinearGradient(0,0,0,300);
  gradient.addColorStop(1,'#000000');
  gradient.addColorStop(0.65,'#000000');
  gradient.addColorStop(0.55,'#FF0000');
  gradient.addColorStop(0.25,'#FFCC00');
  gradient.addColorStop(0,'#ffffff');
  
  if(fbc_array != null){
    ctx.clearRect(0, 0, canvas.width, canvas.height);
  }
  
  ctx.fillStyle = gradient; // Color of the bars
  for (var i = 0; i &lt; (fbc_array.length); i++ ){
    var value = -(fbc_array[i]/4);
    ctx.fillRect(i*5,canvas.height,4,value*2);
  }
  }
  window.addEventListener("load", initMp3Player, false);
  </code></pre>
  
  <p>and HTML:</p>
  
  <pre><code>&lt;audio id="audio-player"&gt;&lt;source src="" type="audio/mpeg"&gt;&lt;/audio&gt;
  </code></pre>
  
  <p>but I receive error: 
  MediaElementAudioSource outputs zeroes due to CORS access restrictions for ...
  I searched very much but i receive a good answer and detail. I'm not really good english, so very super if answers have demo ... thanks </p>