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diff --git a/testing/web-platform/tests/webaudio/resources/panner-formulas.js b/testing/web-platform/tests/webaudio/resources/panner-formulas.js
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+// For the record, these distance formulas were taken from the OpenAL
+// spec
+// (http://connect.creativelabs.com/openal/Documentation/OpenAL%201.1%20Specification.pdf),
+// not the code.  The Web Audio spec follows the OpenAL formulas.
+
+function linearDistance(panner, x, y, z) {
+  let distance = Math.sqrt(x * x + y * y + z * z);
+  let dref = Math.min(panner.refDistance, panner.maxDistance);
+  let dmax = Math.max(panner.refDistance, panner.maxDistance);
+  distance = Math.max(Math.min(distance, dmax), dref);
+  let rolloff = Math.max(Math.min(panner.rolloffFactor, 1), 0);
+  if (dref === dmax)
+    return 1 - rolloff;
+
+  let gain = (1 - rolloff * (distance - dref) / (dmax - dref));
+
+  return gain;
+}
+
+function inverseDistance(panner, x, y, z) {
+  let distance = Math.sqrt(x * x + y * y + z * z);
+  distance = Math.max(distance, panner.refDistance);
+  let rolloff = panner.rolloffFactor;
+  let gain = panner.refDistance /
+      (panner.refDistance +
+       rolloff * (Math.max(distance, panner.refDistance) - panner.refDistance));
+
+  return gain;
+}
+
+function exponentialDistance(panner, x, y, z) {
+  let distance = Math.sqrt(x * x + y * y + z * z);
+  distance = Math.max(distance, panner.refDistance);
+  let rolloff = panner.rolloffFactor;
+  let gain = Math.pow(distance / panner.refDistance, -rolloff);
+
+  return gain;
+}
+
+// Simple implementations of 3D vectors implemented as a 3-element array.
+
+// x - y
+function vec3Sub(x, y) {
+  let z = new Float32Array(3);
+  z[0] = x[0] - y[0];
+  z[1] = x[1] - y[1];
+  z[2] = x[2] - y[2];
+
+  return z;
+}
+
+// x/|x|
+function vec3Normalize(x) {
+  let mag = Math.hypot(...x);
+  return x.map(function(c) {
+    return c / mag;
+  });
+}
+
+// x == 0?
+function vec3IsZero(x) {
+  return x[0] === 0 && x[1] === 0 && x[2] === 0;
+}
+
+// Vector cross product
+function vec3Cross(u, v) {
+  let cross = new Float32Array(3);
+  cross[0] = u[1] * v[2] - u[2] * v[1];
+  cross[1] = u[2] * v[0] - u[0] * v[2];
+  cross[2] = u[0] * v[1] - u[1] * v[0];
+  return cross;
+}
+
+// Dot product
+function vec3Dot(x, y) {
+  return x[0] * y[0] + x[1] * y[1] + x[2] * y[2];
+}
+
+// a*x, for scalar a
+function vec3Scale(a, x) {
+  return x.map(function(c) {
+    return a * c;
+  });
+}
+
+function calculateAzimuth(source, listener, listenerForward, listenerUp) {
+  let sourceListener = vec3Sub(source, listener);
+
+  if (vec3IsZero(sourceListener))
+    return 0;
+
+  sourceListener = vec3Normalize(sourceListener);
+
+  let listenerRight = vec3Normalize(vec3Cross(listenerForward, listenerUp));
+  let listenerForwardNorm = vec3Normalize(listenerForward);
+
+  let up = vec3Cross(listenerRight, listenerForwardNorm);
+  let upProjection = vec3Dot(sourceListener, up);
+
+  let projectedSource =
+      vec3Normalize(vec3Sub(sourceListener, vec3Scale(upProjection, up)));
+
+  let azimuth =
+      180 / Math.PI * Math.acos(vec3Dot(projectedSource, listenerRight));
+
+  // Source in front or behind the listener
+  let frontBack = vec3Dot(projectedSource, listenerForwardNorm);
+  if (frontBack < 0)
+    azimuth = 360 - azimuth;
+
+  // Make azimuth relative to "front" and not "right" listener vector.
+  if (azimuth >= 0 && azimuth <= 270)
+    azimuth = 90 - azimuth;
+  else
+    azimuth = 450 - azimuth;
+
+  // We don't need elevation, so we're skipping that computation.
+  return azimuth;
+}
+
+// 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(azimuth, numberOfChannels) {
+  let halfPi = Math.PI / 2;
+
+  if (azimuth < -90)
+    azimuth = -180 - azimuth;
+  else
+    azimuth = 180 - azimuth;
+
+  if (numberOfChannels == 1) {
+    let panPosition = (azimuth + 90) / 180;
+
+    let gainL = Math.cos(halfPi * panPosition);
+    let gainR = Math.sin(halfPi * panPosition);
+
+    return {left: gainL, right: gainR};
+  } else {
+    if (azimuth <= 0) {
+      let panPosition = (azimuth + 90) / 90;
+
+      let gainL = Math.cos(halfPi * panPosition);
+      let gainR = Math.sin(halfPi * panPosition);
+
+      return {left: gainL, right: gainR};
+    } else {
+      let panPosition = azimuth / 90;
+
+      let gainL = Math.cos(halfPi * panPosition);
+      let gainR = Math.sin(halfPi * panPosition);
+
+      return {left: gainL, right: gainR};
+    }
+  }
+}
+
+function applyPanner(azimuth, srcL, srcR, numberOfChannels) {
+  let length = srcL.length;
+  let outL = new Float32Array(length);
+  let outR = new Float32Array(length);
+
+  if (numberOfChannels == 1) {
+    for (let k = 0; k < length; ++k) {
+      let gains = equalPowerGain(azimuth[k], numberOfChannels);
+
+      outL[k] = srcL[k] * gains.left;
+      outR[k] = srcR[k] * gains.right;
+    }
+  } else {
+    for (let k = 0; k < length; ++k) {
+      let gains = equalPowerGain(azimuth[k], numberOfChannels);
+
+      if (azimuth[k] <= 0) {
+        outL[k] = srcL[k] + srcR[k] * gains.left;
+        outR[k] = srcR[k] * gains.right;
+      } else {
+        outL[k] = srcL[k] * gains.left;
+        outR[k] = srcR[k] + srcL[k] * gains.right;
+      }
+    }
+  }
+
+  return {left: outL, right: outR};
+}