test_pannerNodeHRTFSymmetry.html

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<head>

  <title>Test left/right symmetry and block-offset invariance of HRTF panner</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 blockSize = 128;

const bufferSize = 4096; // > HRTF panner latency

var ctx = new AudioContext();

function startTest() {

  var leftPanner = ctx.createPanner();

  var rightPanner = ctx.createPanner();

  leftPanner.panningModel = "HRTF";

  rightPanner.panningModel = "HRTF";

  leftPanner.positionX.value = -1;

  rightPanner.positionX.value = 1;

  // Test that PannerNode processes the signal consistently irrespective of

  // the offset in the processing block.  This is done by inserting a delay of

  // less than a block size before one panner.

  const delayTime = 0.7 * blockSize / ctx.sampleRate;

  var leftDelay = ctx.createDelay(delayTime);

  leftDelay.delayTime.value = delayTime;

  leftDelay.connect(leftPanner);

  // and compensating for the delay after the other.

  var rightDelay = ctx.createDelay(delayTime);

  rightDelay.delayTime.value = delayTime;

  rightPanner.connect(rightDelay);

  // Feed the panners with a signal having some harmonics to fill the spectrum.

  var oscillator = ctx.createOscillator();

  oscillator.frequency.value = 110;

  oscillator.type = "sawtooth";

  oscillator.connect(leftDelay);

  oscillator.connect(rightPanner);

  oscillator.start(0);

  // Switch the channels on one panner output, and it should match the other.

  var splitter = ctx.createChannelSplitter();

  leftPanner.connect(splitter);

  var merger = ctx.createChannelMerger();

  splitter.connect(merger, 0, 1);

  splitter.connect(merger, 1, 0);

  // Invert one signal so that mixing with the other will find the difference.

  var gain = ctx.createGain();

  gain.gain.value = -1.0;

  merger.connect(gain);

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

  gain.connect(processor);

  rightDelay.connect(processor);

  processor.onaudioprocess =

    function(e) {

      compareBuffers(e.inputBuffer,

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

      e.target.onaudioprocess = null;

      SimpleTest.finish();

promiseHRTFReady(ctx.sampleRate).then(startTest);

</script>

</pre>

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