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<!DOCTYPE HTML>
<html>
<head>
<meta charset="utf-8">
<title>Test DynamicsCompressor with Gain</title>
<script src="/tests/SimpleTest/SimpleTest.js"></script>
<link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
</head>
<body>
<script class="testbody" type="text/javascript">
SimpleTest.waitForExplicitFinish();
addLoadEvent(function() {
var samplerate = 44100;
var context = new OfflineAudioContext(1, samplerate/100, samplerate);
var osc = context.createOscillator();
osc.frequency.value = 2400;
var gain = context.createGain();
gain.gain.value = 1.5;
// These numbers are borrowed from the example code on MDN
// https://developer.mozilla.org/en-US/docs/Web/API/DynamicsCompressorNode
var compressor = context.createDynamicsCompressor();
compressor.threshold.value = -50;
compressor.knee.value = 40;
compressor.ratio.value = 12;
compressor.reduction.value = -20;
compressor.attack.value = 0;
compressor.release.value = 0.25;
osc.connect(gain);
gain.connect(compressor);
compressor.connect(context.destination);
osc.start();
context.startRendering().then(buffer => {
var peak = Math.max(...buffer.getChannelData(0));
console.log(peak);
// These values are experimentally determined. Without dynamics compression
// the peak should be just under 1.5. We also check for a minimum value
// to make sure we are not getting all zeros.
ok(peak >= 0.2 && peak < 1.0, "Peak value should be greater than 0.25 and less than 1.0");
SimpleTest.finish();
});
});
</script>
<pre>
</pre>
</body>
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