test_retrospective-setValueAtTime.html

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<!DOCTYPE html>

<title>Test setValueAtTime with startTime in the past</title>

<script src="/resources/testharness.js"></script>

<script src="/resources/testharnessreport.js"></script>

<script>

function do_test(t, context) {

  var source = context.createConstantSource();

  source.start();

  // Use a ramp of slope 1/sample to measure time.

  // The end value is the extent of exact precision in single precision float.

  const rampEnd = Math.pow(2, 24);

  const rampEndSeconds = rampEnd / context.sampleRate;

  var test = context.createGain();

  test.gain.setValueAtTime(0.0, 0.5*context.currentTime);

  test.gain.linearRampToValueAtTime(rampEnd, rampEndSeconds);

  var reference = context.createGain();

  reference.gain.setValueAtTime(0.0, context.currentTime);

  reference.gain.linearRampToValueAtTime(rampEnd, rampEndSeconds);

  source.connect(test);

  source.connect(reference);

  var merger = context.createChannelMerger();

  test.connect(merger, 0, 0);

  reference.connect(merger, 0, 1);

  var processor = context.createScriptProcessor(0, 2, 0);

  merger.connect(processor);

  processor.onaudioprocess =

    t.step_func_done((e) => {

      source.stop();

      processor.onaudioprocess = null;

      var testValue = e.inputBuffer.getChannelData(0)[0];

      var referenceValue = e.inputBuffer.getChannelData(1)[0];

      assert_equals(testValue, referenceValue,

                        "ramp value matches expected");

});

async_test(function(t) {

  var context = new AudioContext;

  (function waitForTimeAdvance() {

    if (context.currentTime == 0) {

      t.step_timeout(waitForTimeAdvance, 0);

    } else {

      do_test(t, context);

  })();

});

</script>