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<!DOCTYPE HTML>
<html>
<head>
<title>Test AudioParam with pre-gain </title>
<script src="/tests/SimpleTest/SimpleTest.js"></script>
<script type="text/javascript" src="webaudio.js"></script>
<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
</head>
<body>
<pre id="test">
<script class="testbody" type="text/javascript">
SimpleTest.waitForExplicitFinish();
var ctx = new AudioContext();
var source = ctx.createOscillator();
var lfo = ctx.createOscillator();
var lfoIntensity = ctx.createGain();
var effect = ctx.createGain();
var sp = ctx.createScriptProcessor(2048, 1);
source.frequency.value = 440;
lfo.frequency.value = 2;
// Very low gain, so the LFO should have very little influence
// on the source, its RMS value should be close to the nominal value
// for a sine wave.
lfoIntensity.gain.value = 0.0001;
lfo.connect(lfoIntensity);
lfoIntensity.connect(effect.gain);
source.connect(effect);
effect.connect(sp);
sp.onaudioprocess = function(e) {
var buffer = e.inputBuffer.getChannelData(0);
var rms = 0;
for (var i = 0; i < buffer.length; i++) {
rms += buffer[i] * buffer[i];
}
rms /= buffer.length;
rms = Math.sqrt(rms);
// 1 / Math.sqrt(2) is the theoretical RMS value for a sine wave.
ok(fuzzyCompare(rms, 1 / Math.sqrt(2)),
"Gain correctly applied to the AudioParam.");
ctx = null;
sp.onaudioprocess = null;
lfo.stop(0);
source.stop(0);
SimpleTest.finish();
}
lfo.start(0);
source.start(0);
</script>
</pre>
</body>
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