Quelle test_delayNodeCycles.html Sprache: HTML

products/Sources/formale Sprachen/C/Firefox/dom/media/webaudio/test/test_delayNodeCycles.html

<!DOCTYPE HTML>
<html>
<head>
  <title>Test the support of cycles.</title>
  <script src="/tests/SimpleTest/SimpleTest.js"></script>
  <script type="text/javascript" src="webaudio.js"></script>
  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
</head>
<body>
<pre id="test">
<script class="testbody" type="text/javascript">

SimpleTest.waitForExplicitFinish();

const sampleRate = 48000;
const inputLength = 2048;

addLoadEvent(function() {
  function addSine(b) {
    for (var i = 0; i < b.length; i++) {
      b[i] += Math.sin(440 * 2 * Math.PI * i / sampleRate);
    }
  }

  function getSineBuffer(ctx) {
    var buffer = ctx.createBuffer(1, inputLength, ctx.sampleRate);
    addSine(buffer.getChannelData(0));
    return buffer;
  }

  function createAndPlayWithCycleAndDelayNode(ctx, delayFrames) {
    var source = ctx.createBufferSource();
    source.buffer = getSineBuffer(ctx);

    var gain = ctx.createGain();
    var delay = ctx.createDelay();
    delay.delayTime.value = delayFrames/ctx.sampleRate;

    source.connect(gain);
    gain.connect(delay);
    delay.connect(ctx.destination);
    // cycle
    delay.connect(gain);

    source.start(0);
  }

  function createAndPlayWithCycleAndNoDelayNode(ctx) {
    var source = ctx.createBufferSource();
    source.loop = true;
    source.buffer = getSineBuffer(ctx);

    var gain = ctx.createGain();
    var gain2 = ctx.createGain();

    source.connect(gain);
    gain.connect(gain2);
    // cycle
    gain2.connect(gain);
    gain2.connect(ctx.destination);

    source.start(0);
  }

  function createAndPlayWithCycleAndNoDelayNodeInCycle(ctx) {
    var source = ctx.createBufferSource();
    source.loop = true;
    source.buffer = getSineBuffer(ctx);

    var delay = ctx.createDelay();
    var gain = ctx.createGain();
    var gain2 = ctx.createGain();

    // Their is a cycle, a delay, but the delay is not in the cycle.
    source.connect(delay);
    delay.connect(gain);
    gain.connect(gain2);
    // cycle
    gain2.connect(gain);
    gain2.connect(ctx.destination);

    source.start(0);
  }

  var remainingTests = 0;
  function finish() {
    if (--remainingTests == 0) {
      SimpleTest.finish();
    }
  }

  function getOfflineContext(oncomplete) {
    var ctx = new OfflineAudioContext(1, sampleRate, sampleRate);
    ctx.oncomplete = oncomplete;
    return ctx;
  }

  function checkSilentBuffer(e) {
    var buffer = e.renderedBuffer.getChannelData(0);
    for (var i = 0; i < buffer.length; i++) {
      if (buffer[i] != 0.0) {
        ok(false, "buffer should be silent.");
        finish();
        return;
      }
    }
    ok(true, "buffer should be silent.");
    finish();
  }

  function checkNoisyBuffer(e, aDelayFrames) {
    let delayFrames = Math.max(128, aDelayFrames);

    var expected = new Float32Array(e.renderedBuffer.length);
    for (var i = delayFrames; i < expected.length; i += delayFrames) {
      addSine(expected.subarray(i, i + inputLength));
    }

    compareChannels(e.renderedBuffer.getChannelData(0), expected);
    finish();
  }

  function expectSilentOutput(f) {
    remainingTests++;
    var ctx = getOfflineContext(checkSilentBuffer);
    f(ctx);
    ctx.startRendering();
  }

  function expectNoisyOutput(delayFrames) {
    remainingTests++;
    var ctx = getOfflineContext();
    ctx.oncomplete = function(e) { checkNoisyBuffer(e, delayFrames); };
    createAndPlayWithCycleAndDelayNode(ctx, delayFrames);
    ctx.startRendering();
  }

  // This is trying to make a graph with a cycle and no DelayNode in the graph.
  // The cycle subgraph should be muted, in this graph the output should be silent.
  expectSilentOutput(createAndPlayWithCycleAndNoDelayNode);
  // This is trying to make a graph with a cycle and a DelayNode in the graph, but
  // not part of the cycle.
  // The cycle subgraph should be muted, in this graph the output should be silent.
  expectSilentOutput(createAndPlayWithCycleAndNoDelayNodeInCycle);
  // Those are making legal graphs, with at least one DelayNode in the cycle.
  // There should be some non-silent output.
  expectNoisyOutput(sampleRate/4);
  // DelayNode.delayTime will be clamped to 128/ctx.sampleRate.
  // There should be some non-silent output.
  expectNoisyOutput(0);
});

</script>
</pre>
</body>
</html>

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