test_audioParamChaining.html

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<head>

  <title>Test whether we can create an AudioContext interface</title>

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

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

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<pre id="test">

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

SimpleTest.waitForExplicitFinish()

function frameToTime(frame, rate)

  return frame / rate;

const RATE = 44100;

var oc = new OfflineAudioContext(1, 44100, RATE);

// This allows us to have a source that is simply a DC offset.

var source = oc.createBufferSource();

var buf = oc.createBuffer(1, 1, RATE);

buf.getChannelData(0)[0] = 1;

source.loop = true;

source.buffer = buf;

source.start(0);

var gain = oc.createGain();

source.connect(gain).connect(oc.destination);

var gain2 = oc.createGain();

var rv2 = gain2.gain.linearRampToValueAtTime(0.1, 0.5);

ok(rv2 instanceof AudioParam, "linearRampToValueAtTime returns an AudioParam.");

ok(rv2 == gain2.gain, "linearRampToValueAtTime returns the right AudioParam.");

rv2 = gain2.gain.exponentialRampToValueAtTime(0.01, 1.0);

ok(rv2 instanceof AudioParam,

    "exponentialRampToValueAtTime returns an AudioParam.");

ok(rv2 == gain2.gain,

    "exponentialRampToValueAtTime returns the right AudioParam.");

rv2 = gain2.gain.setTargetAtTime(1.0, 2.0, 0.1);

ok(rv2 instanceof AudioParam, "setTargetAtTime returns an AudioParam.");

ok(rv2 == gain2.gain, "setTargetAtTime returns the right AudioParam.");

var array = new Float32Array(10);

rv2 = gain2.gain.setValueCurveAtTime(array, 10, 11);

ok(rv2 instanceof AudioParam, "setValueCurveAtTime returns an AudioParam.");

ok(rv2 == gain2.gain, "setValueCurveAtTime returns the right AudioParam.");

// We chain three automation methods, making a gain step.

var rv = gain.gain.setValueAtTime(0, frameToTime(0, RATE))

                  .setValueAtTime(0.5, frameToTime(22000, RATE))

                  .setValueAtTime(1, frameToTime(44000, RATE));

ok(rv instanceof AudioParam, "setValueAtTime returns an AudioParam.");

ok(rv == gain.gain, "setValueAtTime returns the right AudioParam.");

oc.startRendering().then(function(rendered) {

    console.log(rendered.getChannelData(0));

    is(rendered.getChannelData(0)[0], 0,

      "The value of the first step is correct.");

    is(rendered.getChannelData(0)[22050], 0.5,

      "The value of the second step is correct");

    is(rendered.getChannelData(0)[44099], 1,

      "The value of the third step is correct.");

    SimpleTest.finish();

});

</script>

</pre>

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