The Tor Browser: content/media/webaudio/test/test_audioParamGain.html@6474c204b198

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

     1 <!DOCTYPE HTML>

     2 <html>

     3 <head>

     4   <title>Test AudioParam with pre-gain </title>

     5   <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>

     6   <script type="text/javascript" src="webaudio.js"></script>

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

     8 </head>

     9 <body>

    10 <pre id="test">

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

    13 SimpleTest.waitForExplicitFinish();

    15 var ctx = new AudioContext();

    16 var source = ctx.createOscillator();

    17 var lfo = ctx.createOscillator();

    18 var lfoIntensity = ctx.createGain();

    19 var effect = ctx.createGain();

    20 var sp = ctx.createScriptProcessor(2048, 1);

    22 source.frequency.value = 440;

    23 lfo.frequency.value = 2;

    24 // Very low gain, so the LFO should have very little influence

    25 // on the source, its RMS value should be close to the nominal value

    26 // for a sine wave.

    27 lfoIntensity.gain.value = 0.0001;

    29 lfo.connect(lfoIntensity);

    30 lfoIntensity.connect(effect.gain);

    31 source.connect(effect);

    32 effect.connect(sp);

    34 sp.onaudioprocess = function(e) {

    35   var buffer = e.inputBuffer.getChannelData(0);

    36   var rms = 0;

    37   for (var i = 0; i < buffer.length; i++) {

    38     rms += buffer[i] * buffer[i];

    39   }

    41   rms /= buffer.length;

    42   rms = Math.sqrt(rms);

    44   // 1 / Math.sqrt(2) is the theoretical RMS value for a sine wave.

    45   ok(fuzzyCompare(rms, 1 / Math.sqrt(2)),

    46       "Gain correctly applied to the AudioParam.");

    48   ctx = null;

    49   sp.onaudioprocess = null;

    50   lfo.stop(0);

    51   source.stop(0);

    53   SimpleTest.finish();

    54 }

    56 lfo.start(0);

    57 source.start(0);

    59 </script>

    60 </pre>

    61 </body>

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