1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/content/media/webaudio/test/test_audioParamGain.html Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,61 @@
1.4 +<!DOCTYPE HTML>
1.5 +<html>
1.6 +<head>
1.7 + <title>Test AudioParam with pre-gain </title>
1.8 + <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
1.9 + <script type="text/javascript" src="webaudio.js"></script>
1.10 + <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
1.11 +</head>
1.12 +<body>
1.13 +<pre id="test">
1.14 +<script class="testbody" type="text/javascript">
1.15 +
1.16 +SimpleTest.waitForExplicitFinish();
1.17 +
1.18 +var ctx = new AudioContext();
1.19 +var source = ctx.createOscillator();
1.20 +var lfo = ctx.createOscillator();
1.21 +var lfoIntensity = ctx.createGain();
1.22 +var effect = ctx.createGain();
1.23 +var sp = ctx.createScriptProcessor(2048, 1);
1.24 +
1.25 +source.frequency.value = 440;
1.26 +lfo.frequency.value = 2;
1.27 +// Very low gain, so the LFO should have very little influence
1.28 +// on the source, its RMS value should be close to the nominal value
1.29 +// for a sine wave.
1.30 +lfoIntensity.gain.value = 0.0001;
1.31 +
1.32 +lfo.connect(lfoIntensity);
1.33 +lfoIntensity.connect(effect.gain);
1.34 +source.connect(effect);
1.35 +effect.connect(sp);
1.36 +
1.37 +sp.onaudioprocess = function(e) {
1.38 + var buffer = e.inputBuffer.getChannelData(0);
1.39 + var rms = 0;
1.40 + for (var i = 0; i < buffer.length; i++) {
1.41 + rms += buffer[i] * buffer[i];
1.42 + }
1.43 +
1.44 + rms /= buffer.length;
1.45 + rms = Math.sqrt(rms);
1.46 +
1.47 + // 1 / Math.sqrt(2) is the theoretical RMS value for a sine wave.
1.48 + ok(fuzzyCompare(rms, 1 / Math.sqrt(2)),
1.49 + "Gain correctly applied to the AudioParam.");
1.50 +
1.51 + ctx = null;
1.52 + sp.onaudioprocess = null;
1.53 + lfo.stop(0);
1.54 + source.stop(0);
1.55 +
1.56 + SimpleTest.finish();
1.57 +}
1.58 +
1.59 +lfo.start(0);
1.60 +source.start(0);
1.61 +
1.62 +</script>
1.63 +</pre>
1.64 +</body>
