test_delayNodeChannelChanges.html

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<head>

  <title>test DelayNode channel count changes</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();

SimpleTest.requestCompleteLog();

const bufferSize = 4096;

var ctx;

var testDelay;

var stereoDelay;

var invertor;

function compareOutputs(callback) {

  var processor = ctx.createScriptProcessor(bufferSize, 2, 0);

  testDelay.connect(processor);

  invertor.connect(processor);

  processor.onaudioprocess =

    function(e) {

      compareBuffers(e.inputBuffer,

                     ctx.createBuffer(2, bufferSize, ctx.sampleRate));

      e.target.onaudioprocess = null;

      callback();

function startTest() {

  // And a two-channel signal

  var merger = ctx.createChannelMerger();

  merger.connect(testDelay);

  merger.connect(stereoDelay);

  var oscL = ctx.createOscillator();

  oscL.connect(merger, 0, 0);

  oscL.start(0);

  var oscR = ctx.createOscillator();

  oscR.type = "sawtooth";

  oscR.connect(merger, 0, 1);

  oscR.start(0);

  compareOutputs(

    function () {

      // Disconnect the two-channel signal and test again

      merger.disconnect();

      compareOutputs(SimpleTest.finish);

});

function prepareTest() {

  ctx = new AudioContext();

  // The output of a test delay node with mono and stereo input will be

  // compared with that of separate mono and stereo delay nodes.

  const delayTime = 0.3 * bufferSize / ctx.sampleRate;

  testDelay = ctx.createDelay(delayTime);

  testDelay.delayTime.value = delayTime;

  let monoDelay = ctx.createDelay(delayTime);

  monoDelay.delayTime.value = delayTime;

  stereoDelay = ctx.createDelay(delayTime);

  stereoDelay.delayTime.value = delayTime;

  // Create a one-channel signal and connect to the delay nodes

  var monoOsc = ctx.createOscillator();

  monoOsc.frequency.value = 110;

  monoOsc.connect(testDelay);

  monoOsc.connect(monoDelay);

  monoOsc.start(0);

  // Invert the expected so that mixing with the test will find the difference.

  invertor = ctx.createGain();

  invertor.gain.value = -1.0;

  monoDelay.connect(invertor);

  stereoDelay.connect(invertor);

  // Start the test after the delay nodes have begun processing.

  var processor = ctx.createScriptProcessor(bufferSize, 1, 0);

  processor.connect(ctx.destination);

  processor.onaudioprocess =

    function(e) {

      e.target.onaudioprocess = null;

      processor.disconnect();

      startTest();

};

prepareTest();

</script>

</pre>

</body>

</html>