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index.html
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index.html
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<html>
<head>
<script type="application/javascript">
var audioContext, gainNode, whiteNoise, pinkNoise, brownNoise;
function init() {
if (audioContext) {
return;
}
else {
audioContext = new (window.AudioContext || window.webkitAudioContext)();
gainNode = audioContext.createGain();
gainNode.gain.value = 0.3;
gainNode.connect(audioContext.destination);
var bufferSize = 16384;
whiteNoise = audioContext.createScriptProcessor(bufferSize, 1, 1);
whiteNoise.onaudioprocess = function(e) {
var output = e.outputBuffer.getChannelData(0);
for (var i = 0; i < bufferSize; i++) {
output[i] = (Math.random() * 2 - 1) * 0.8;
}
};
pinkNoise = (function() {
var b0, b1, b2, b3, b4, b5, b6;
b0 = b1 = b2 = b3 = b4 = b5 = b6 = 0.0;
var node = audioContext.createScriptProcessor(bufferSize, 1, 1);
node.onaudioprocess = function(e) {
var output = e.outputBuffer.getChannelData(0);
for (var i = 0; i < bufferSize; i++) {
var white = Math.random() * 2 - 1;
b0 = 0.99886 * b0 + white * 0.0555179;
b1 = 0.99332 * b1 + white * 0.0750759;
b2 = 0.96900 * b2 + white * 0.1538520;
b3 = 0.86650 * b3 + white * 0.3104856;
b4 = 0.55000 * b4 + white * 0.5329522;
b5 = -0.7616 * b5 - white * 0.0168980;
output[i] = b0 + b1 + b2 + b3 + b4 + b5 + b6 + white * 0.5362;
output[i] *= 0.2; // (roughly) compensate for gain
b6 = white * 0.115926;
}
};
return node;
})();
brownNoise = (function() {
var lastOut = 0.0;
var node = audioContext.createScriptProcessor(bufferSize, 1, 1);
node.onaudioprocess = function(e) {
var output = e.outputBuffer.getChannelData(0);
for (var i = 0; i < bufferSize; i++) {
var white = Math.random() * 2 - 1;
output[i] = (lastOut + (0.02 * white)) / 1.02;
lastOut = output[i];
output[i] *= 6.5; // (roughly) compensate for gain
}
};
return node;
})();
}
}
function onSlider() {
gainNode.gain.value = document.querySelector('#volume').value / 100;
document.querySelector('#vol-value').value = gainNode.gain.value;
}
function connectWhite() {
init();
pinkNoise.disconnect();
brownNoise.disconnect();
whiteNoise.connect(gainNode);
}
function connectPink() {
init();
whiteNoise.disconnect();
brownNoise.disconnect();
pinkNoise.connect(gainNode);
}
function connectBrown() {
init();
whiteNoise.disconnect();
pinkNoise.disconnect();
brownNoise.connect(gainNode);
}
function stop() {
init();
whiteNoise.disconnect();
pinkNoise.disconnect();
brownNoise.disconnect();
}
</script>
<style type="text/css">
input[type=text] {
width: 4em;
text-align: right;
}
input[type=range] {
width: 250px;
}
</style>
</head>
<body>
<button id="white-btn" onclick="connectWhite()">
White Noise
</button>
<button id="pink-btn" onclick="connectPink()">
Pink Noise
</button>
<button id="brown-btn" onclick="connectBrown()">
Brownian Noise
</button>
<button id="stop-btn" onclick="stop()">
Stop
</button>
<form>
<p>Volume:<br/>
<input type="text" id="vol-value" value="30" readonly>
<input type="range" id="volume" value="30" min="0" max="100" step="1" onchange="onSlider()">
</p>
</form>
</body>
</html>