1 files changed, 168 insertions, 0 deletions
diff --git a/testing/web-platform/tests/webaudio/resources/convolution-testing.js b/testing/web-platform/tests/webaudio/resources/convolution-testing.js
new file mode 100644
index 0000000000..c976f86c78
--- /dev/null
+++ b/testing/web-platform/tests/webaudio/resources/convolution-testing.js
@@ -0,0 +1,168 @@
+let sampleRate = 44100.0;
+
+let renderLengthSeconds = 8;
+let pulseLengthSeconds = 1;
+let pulseLengthFrames = pulseLengthSeconds * sampleRate;
+
+function createSquarePulseBuffer(context, sampleFrameLength) {
+  let audioBuffer =
+      context.createBuffer(1, sampleFrameLength, context.sampleRate);
+
+  let n = audioBuffer.length;
+  let data = audioBuffer.getChannelData(0);
+
+  for (let i = 0; i < n; ++i)
+    data[i] = 1;
+
+  return audioBuffer;
+}
+
+// The triangle buffer holds the expected result of the convolution.
+// It linearly ramps up from 0 to its maximum value (at the center)
+// then linearly ramps down to 0.  The center value corresponds to the
+// point where the two square pulses overlap the most.
+function createTrianglePulseBuffer(context, sampleFrameLength) {
+  let audioBuffer =
+      context.createBuffer(1, sampleFrameLength, context.sampleRate);
+
+  let n = audioBuffer.length;
+  let halfLength = n / 2;
+  let data = audioBuffer.getChannelData(0);
+
+  for (let i = 0; i < halfLength; ++i)
+    data[i] = i + 1;
+
+  for (let i = halfLength; i < n; ++i)
+    data[i] = n - i - 1;
+
+  return audioBuffer;
+}
+
+function log10(x) {
+  return Math.log(x) / Math.LN10;
+}
+
+function linearToDecibel(x) {
+  return 20 * log10(x);
+}
+
+// Verify that the rendered result is very close to the reference
+// triangular pulse.
+function checkTriangularPulse(rendered, reference, should) {
+  let match = true;
+  let maxDelta = 0;
+  let valueAtMaxDelta = 0;
+  let maxDeltaIndex = 0;
+
+  for (let i = 0; i < reference.length; ++i) {
+    let diff = rendered[i] - reference[i];
+    let x = Math.abs(diff);
+    if (x > maxDelta) {
+      maxDelta = x;
+      valueAtMaxDelta = reference[i];
+      maxDeltaIndex = i;
+    }
+  }
+
+  // allowedDeviationFraction was determined experimentally.  It
+  // is the threshold of the relative error at the maximum
+  // difference between the true triangular pulse and the
+  // rendered pulse.
+  let allowedDeviationDecibels = -124.41;
+  let maxDeviationDecibels = linearToDecibel(maxDelta / valueAtMaxDelta);
+
+  should(
+      maxDeviationDecibels,
+      'Deviation (in dB) of triangular portion of convolution')
+      .beLessThanOrEqualTo(allowedDeviationDecibels);
+
+  return match;
+}
+
+// Verify that the rendered data is close to zero for the first part
+// of the tail.
+function checkTail1(data, reference, breakpoint, should) {
+  let isZero = true;
+  let tail1Max = 0;
+
+  for (let i = reference.length; i < reference.length + breakpoint; ++i) {
+    let mag = Math.abs(data[i]);
+    if (mag > tail1Max) {
+      tail1Max = mag;
+    }
+  }
+
+  // Let's find the peak of the reference (even though we know a
+  // priori what it is).
+  let refMax = 0;
+  for (let i = 0; i < reference.length; ++i) {
+    refMax = Math.max(refMax, Math.abs(reference[i]));
+  }
+
+  // This threshold is experimentally determined by examining the
+  // value of tail1MaxDecibels.
+  let threshold1 = -129.7;
+
+  let tail1MaxDecibels = linearToDecibel(tail1Max / refMax);
+  should(tail1MaxDecibels, 'Deviation in first part of tail of convolutions')
+      .beLessThanOrEqualTo(threshold1);
+
+  return isZero;
+}
+
+// Verify that the second part of the tail of the convolution is
+// exactly zero.
+function checkTail2(data, reference, breakpoint, should) {
+  let isZero = true;
+  let tail2Max = 0;
+  // For the second part of the tail, the maximum value should be
+  // exactly zero.
+  let threshold2 = 0;
+  for (let i = reference.length + breakpoint; i < data.length; ++i) {
+    if (Math.abs(data[i]) > 0) {
+      isZero = false;
+      break;
+    }
+  }
+
+  should(isZero, 'Rendered signal after tail of convolution is silent')
+      .beTrue();
+
+  return isZero;
+}
+
+function checkConvolvedResult(renderedBuffer, trianglePulse, should) {
+  let referenceData = trianglePulse.getChannelData(0);
+  let renderedData = renderedBuffer.getChannelData(0);
+
+  let success = true;
+
+  // Verify the triangular pulse is actually triangular.
+
+  success =
+      success && checkTriangularPulse(renderedData, referenceData, should);
+
+  // Make sure that portion after convolved portion is totally
+  // silent.  But round-off prevents this from being completely
+  // true.  At the end of the triangle, it should be close to
+  // zero.  If we go farther out, it should be even closer and
+  // eventually zero.
+
+  // For the tail of the convolution (where the result would be
+  // theoretically zero), we partition the tail into two
+  // parts.  The first is the at the beginning of the tail,
+  // where we tolerate a small but non-zero value.  The second part is
+  // farther along the tail where the result should be zero.
+
+  // breakpoint is the point dividing the first two tail parts
+  // we're looking at.  Experimentally determined.
+  let breakpoint = 12800;
+
+  success =
+      success && checkTail1(renderedData, referenceData, breakpoint, should);
+
+  success =
+      success && checkTail2(renderedData, referenceData, breakpoint, should);
+
+  should(success, 'Test signal convolved').message('correctly', 'incorrectly');
+}