b-ma/index.html

## index.html
<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8" />
    <title></title>
</head>
<body>
  <button>play/pause</button>
  <script>
  var audioCtx = new AudioContext();

  var sampleRate = audioCtx.sampleRate;
  var length = sampleRate;
  var audioBuffer = audioCtx.createBuffer(1, length, sampleRate);

  var buffer = audioBuffer.getChannelData(0);

  console.time('populateBuffer');
  for (var i = 0; i < length; i++) {
    var value = Math.random() * 2 - 1;
    value = value * value * value * value;
    // scale
    buffer[i] = value * 0.03;
  }

  // beat
  for (var i = 0; i < 20; i++) {
    buffer[i] = 1;
  }

  // third
  var step = length / 3;
  for (var i = 0; i < 3; i++) {
    for (var j = 0; j < 4; j++) {
      buffer[step * i + j] = 0.85;
    }
  }

  var step = length / 4;
  for (var i = 0; i < 4; i++) {
    for (var j = 0; j < 4; j++) {
      buffer[step * i + j] = 0.5;
    }
  }

  var step = length / 5;
  for (var i = 0; i < 5; i++) {
    for (var j = 0; j < 7; j++) {
      buffer[step * i + j] = j % 2 ? 0.8 : 0.4;
    }
  }

  var step = length / 10;
  for (var i = 0; i < 10; i++) {
    for (var j = 0; j < 10; j++) {
      buffer[step * i + j] = j % 2 ? 0.4 : -0.2;
    }
  }
  console.timeEnd('populateBuffer');

  var source = audioCtx.createBufferSource();
  source.buffer = audioBuffer;
  source.loop = true;

  var gain = audioCtx.createGain();

  source.connect(gain);
  gain.connect(audioCtx.destination);

  source.start(audioCtx.currentTime);

  var state = 'playing';
  document.querySelector('button').addEventListener('click', function() {
    if (state === 'playing') {
      gain.gain.value = 0;
      state = 'paused';
    } else {
      gain.gain.value = 1;
      state = 'playing';
    }
  })
  </script>
</body>
</html>
	<!DOCTYPE html>
	<html>
	<head>
	<meta charset="utf-8" />
	<title></title>
	</head>
	<body>
	<button>play/pause</button>
	<script>
	var audioCtx = new AudioContext();

	var sampleRate = audioCtx.sampleRate;
	var length = sampleRate;
	var audioBuffer = audioCtx.createBuffer(1, length, sampleRate);

	var buffer = audioBuffer.getChannelData(0);

	console.time('populateBuffer');
	for (var i = 0; i < length; i++) {
	var value = Math.random() * 2 - 1;
	value = value * value * value * value;
	// scale
	buffer[i] = value * 0.03;
	}

	// beat
	for (var i = 0; i < 20; i++) {
	buffer[i] = 1;
	}

	// third
	var step = length / 3;
	for (var i = 0; i < 3; i++) {
	for (var j = 0; j < 4; j++) {
	buffer[step * i + j] = 0.85;
	}
	}

	var step = length / 4;
	for (var i = 0; i < 4; i++) {
	for (var j = 0; j < 4; j++) {
	buffer[step * i + j] = 0.5;
	}
	}

	var step = length / 5;
	for (var i = 0; i < 5; i++) {
	for (var j = 0; j < 7; j++) {
	buffer[step * i + j] = j % 2 ? 0.8 : 0.4;
	}
	}

	var step = length / 10;
	for (var i = 0; i < 10; i++) {
	for (var j = 0; j < 10; j++) {
	buffer[step * i + j] = j % 2 ? 0.4 : -0.2;
	}
	}
	console.timeEnd('populateBuffer');

	var source = audioCtx.createBufferSource();
	source.buffer = audioBuffer;
	source.loop = true;

	var gain = audioCtx.createGain();

	source.connect(gain);
	gain.connect(audioCtx.destination);

	source.start(audioCtx.currentTime);

	var state = 'playing';
	document.querySelector('button').addEventListener('click', function() {
	if (state === 'playing') {
	gain.gain.value = 0;
	state = 'paused';
	} else {
	gain.gain.value = 1;
	state = 'playing';
	}
	})
	</script>
	</body>
	</html>