test_dynamicsCompressorNode.html

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<html>

<head>

  <title>Test DynamicsCompressorNode</title>

  <script src="/tests/SimpleTest/SimpleTest.js"></script>

  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />

</head>

<body>

<pre id="test">

<script class="testbody" type="text/javascript">

function near(a, b, msg) {

  ok(Math.abs(a - b) < 1e-4, msg);

SimpleTest.waitForExplicitFinish();

addLoadEvent(function() {

  var context = new AudioContext();

  var osc = context.createOscillator();

  var sp = context.createScriptProcessor();

  var compressor = new DynamicsCompressorNode(context);

  osc.connect(compressor);

  osc.connect(sp);

  compressor.connect(context.destination);

  is(compressor.channelCount, 2, "compressor node has 2 input channels by default");

  is(compressor.channelCountMode, "clamped-max", "Correct channelCountMode for the compressor node");

  is(compressor.channelInterpretation, "speakers", "Correct channelCountInterpretation for the compressor node");

  // Verify default values

  ok(compressor.threshold instanceof AudioParam, "treshold is an AudioParam");

  near(compressor.threshold.defaultValue, -24, "Correct default value for threshold");

  ok(compressor.knee instanceof AudioParam, "knee is an AudioParam");

  near(compressor.knee.defaultValue, 30, "Correct default value for knee");

  ok(compressor.ratio instanceof AudioParam, "knee is an AudioParam");

  near(compressor.ratio.defaultValue, 12, "Correct default value for ratio");

  is(typeof compressor.reduction, "number", "reduction is a number");

  near(compressor.reduction, 0, "Correct default value for reduction");

  ok(compressor.attack instanceof AudioParam, "attack is an AudioParam");

  near(compressor.attack.defaultValue, 0.003, "Correct default value for attack");

  ok(compressor.release instanceof AudioParam, "release is an AudioParam");

  near(compressor.release.defaultValue, 0.25, "Correct default value for release");

  compressor.threshold.value = -80;

  osc.start();

  var iteration = 0;

  sp.onaudioprocess = function() {

    if (iteration > 10) {

      ok(compressor.reduction < 0,

         "Feeding a full-scale sine to a compressor should result in an db" +

         "reduction.");

      sp.onaudioprocess = null;

      osc.stop(0);

      SimpleTest.finish();

    iteration++;

});

</script>

</pre>

</body>

</html>