1 files changed, 184 insertions, 0 deletions
diff --git a/testing/web-platform/tests/webaudio/resources/panner-model-testing.js b/testing/web-platform/tests/webaudio/resources/panner-model-testing.js
new file mode 100644
index 0000000000..4df3e17813
--- /dev/null
+++ b/testing/web-platform/tests/webaudio/resources/panner-model-testing.js
@@ -0,0 +1,184 @@
+// Use a power of two to eliminate round-off when converting frames to time and
+// vice versa.
+let sampleRate = 32768;
+
+let numberOfChannels = 1;
+
+// Time step when each panner node starts.  Make sure it starts on a frame
+// boundary.
+let timeStep = Math.floor(0.001 * sampleRate) / sampleRate;
+
+// Length of the impulse signal.
+let pulseLengthFrames = Math.round(timeStep * sampleRate);
+
+// How many panner nodes to create for the test
+let nodesToCreate = 100;
+
+// Be sure we render long enough for all of our nodes.
+let renderLengthSeconds = timeStep * (nodesToCreate + 1);
+
+// These are global mostly for debugging.
+let context;
+let impulse;
+let bufferSource;
+let panner;
+let position;
+let time;
+
+let renderedBuffer;
+let renderedLeft;
+let renderedRight;
+
+function createGraph(context, nodeCount, positionSetter) {
+  bufferSource = new Array(nodeCount);
+  panner = new Array(nodeCount);
+  position = new Array(nodeCount);
+  time = new Array(nodeCount);
+  // Angle between panner locations.  (nodeCount - 1 because we want
+  // to include both 0 and 180 deg.
+  let angleStep = Math.PI / (nodeCount - 1);
+
+  if (numberOfChannels == 2) {
+    impulse = createStereoImpulseBuffer(context, pulseLengthFrames);
+  } else
+    impulse = createImpulseBuffer(context, pulseLengthFrames);
+
+  for (let k = 0; k < nodeCount; ++k) {
+    bufferSource[k] = context.createBufferSource();
+    bufferSource[k].buffer = impulse;
+
+    panner[k] = context.createPanner();
+    panner[k].panningModel = 'equalpower';
+    panner[k].distanceModel = 'linear';
+
+    let angle = angleStep * k;
+    position[k] = {angle: angle, x: Math.cos(angle), z: Math.sin(angle)};
+    positionSetter(panner[k], position[k].x, 0, position[k].z);
+
+    bufferSource[k].connect(panner[k]);
+    panner[k].connect(context.destination);
+
+    // Start the source
+    time[k] = k * timeStep;
+    bufferSource[k].start(time[k]);
+  }
+}
+
+function createTestAndRun(
+    context, should, nodeCount, numberOfSourceChannels, positionSetter) {
+  numberOfChannels = numberOfSourceChannels;
+
+  createGraph(context, nodeCount, positionSetter);
+
+  return context.startRendering().then(buffer => checkResult(buffer, should));
+}
+
+// Map our position angle to the azimuth angle (in degrees).
+//
+// An angle of 0 corresponds to an azimuth of 90 deg; pi, to -90 deg.
+function angleToAzimuth(angle) {
+  return 90 - angle * 180 / Math.PI;
+}
+
+// The gain caused by the EQUALPOWER panning model
+function equalPowerGain(angle) {
+  let azimuth = angleToAzimuth(angle);
+
+  if (numberOfChannels == 1) {
+    let panPosition = (azimuth + 90) / 180;
+
+    let gainL = Math.cos(0.5 * Math.PI * panPosition);
+    let gainR = Math.sin(0.5 * Math.PI * panPosition);
+
+    return {left: gainL, right: gainR};
+  } else {
+    if (azimuth <= 0) {
+      let panPosition = (azimuth + 90) / 90;
+
+      let gainL = 1 + Math.cos(0.5 * Math.PI * panPosition);
+      let gainR = Math.sin(0.5 * Math.PI * panPosition);
+
+      return {left: gainL, right: gainR};
+    } else {
+      let panPosition = azimuth / 90;
+
+      let gainL = Math.cos(0.5 * Math.PI * panPosition);
+      let gainR = 1 + Math.sin(0.5 * Math.PI * panPosition);
+
+      return {left: gainL, right: gainR};
+    }
+  }
+}
+
+function checkResult(renderedBuffer, should) {
+  renderedLeft = renderedBuffer.getChannelData(0);
+  renderedRight = renderedBuffer.getChannelData(1);
+
+  // The max error we allow between the rendered impulse and the
+  // expected value.  This value is experimentally determined.  Set
+  // to 0 to make the test fail to see what the actual error is.
+  let maxAllowedError = 1.1597e-6;
+
+  let success = true;
+
+  // Number of impulses found in the rendered result.
+  let impulseCount = 0;
+
+  // Max (relative) error and the index of the maxima for the left
+  // and right channels.
+  let maxErrorL = 0;
+  let maxErrorIndexL = 0;
+  let maxErrorR = 0;
+  let maxErrorIndexR = 0;
+
+  // Number of impulses that don't match our expected locations.
+  let timeCount = 0;
+
+  // Locations of where the impulses aren't at the expected locations.
+  let timeErrors = new Array();
+
+  for (let k = 0; k < renderedLeft.length; ++k) {
+    // We assume that the left and right channels start at the same instant.
+    if (renderedLeft[k] != 0 || renderedRight[k] != 0) {
+      // The expected gain for the left and right channels.
+      let pannerGain = equalPowerGain(position[impulseCount].angle);
+      let expectedL = pannerGain.left;
+      let expectedR = pannerGain.right;
+
+      // Absolute error in the gain.
+      let errorL = Math.abs(renderedLeft[k] - expectedL);
+      let errorR = Math.abs(renderedRight[k] - expectedR);
+
+      if (Math.abs(errorL) > maxErrorL) {
+        maxErrorL = Math.abs(errorL);
+        maxErrorIndexL = impulseCount;
+      }
+      if (Math.abs(errorR) > maxErrorR) {
+        maxErrorR = Math.abs(errorR);
+        maxErrorIndexR = impulseCount;
+      }
+
+      // Keep track of the impulses that didn't show up where we
+      // expected them to be.
+      let expectedOffset = timeToSampleFrame(time[impulseCount], sampleRate);
+      if (k != expectedOffset) {
+        timeErrors[timeCount] = {actual: k, expected: expectedOffset};
+        ++timeCount;
+      }
+      ++impulseCount;
+    }
+  }
+
+  should(impulseCount, 'Number of impulses found').beEqualTo(nodesToCreate);
+
+  should(
+      timeErrors.map(x => x.actual),
+      'Offsets of impulses at the wrong position')
+      .beEqualToArray(timeErrors.map(x => x.expected));
+
+  should(maxErrorL, 'Error in left channel gain values')
+      .beLessThanOrEqualTo(maxAllowedError);
+
+  should(maxErrorR, 'Error in right channel gain values')
+      .beLessThanOrEqualTo(maxAllowedError);
+}