From 608ba49515ab0401c0572cbb0c12376485ace0ef Mon Sep 17 00:00:00 2001
From: Hongchan Choi <hongchan@chromium.org>
Date: Mon, 7 Nov 2016 11:53:47 -0800
Subject: [PATCH 1/4] progress

---
 README.md                       |   4 +-
 src/foa-phase-matched-filter.js |  12 ++-
 test/index.html                 |   1 +
 test/test-phasematchedfilter.js |  77 ++++++++++++++++++
 test/test-setup.js              | 136 ++++++++++++++++++++++++++++++++
 5 files changed, 224 insertions(+), 6 deletions(-)
 create mode 100644 test/test-phasematchedfilter.js

diff --git a/README.md b/README.md
index 17db2fe..200ffc7 100644
--- a/README.md
+++ b/README.md
@@ -108,7 +108,7 @@ Omnitone also provides various building blocks for the first-order-ambisonic dec
 ```js
 var decoder = Omnitone.createFOADecoder(context, element, {
   HRTFSetUrl: 'YOUR_HRTF_SET_URL',
-  postGainDB: 30,
+  postGainDB: 0,
   channelMap: [0, 1, 2, 3]
 });
 ```
@@ -217,7 +217,7 @@ Omnitone is designed to run any browser that supports Web Audio API, however, it
 ## Related Resources
 
 * [Google Spatial Media](https://github.com/google/spatial-media)
-* [VRView](https://developers.google.com/vr/concepts/vrview/)
+* [VR view](https://developers.google.com/vr/concepts/vrview/)
 * [Web Audio API](https://webaudio.github.io/web-audio-api/)
 * [WebVR](https://webvr.info/)
 
diff --git a/src/foa-phase-matched-filter.js b/src/foa-phase-matched-filter.js
index aba424d..5f6bed9 100644
--- a/src/foa-phase-matched-filter.js
+++ b/src/foa-phase-matched-filter.js
@@ -96,10 +96,14 @@ function FOAPhaseMatchedFilter (context) {
   // Apply gain correction to hi-passed pressure and velocity components:
   // Inverting sign is necessary as the low-passed and high-passed portion are
   // out-of-phase after the filtering.
-  this._gainHighW.gain.value = -1 * GAIN_COEFFICIENTS[0];
-  this._gainHighY.gain.value = -1 * GAIN_COEFFICIENTS[1];
-  this._gainHighZ.gain.value = -1 * GAIN_COEFFICIENTS[2];
-  this._gainHighX.gain.value = -1 * GAIN_COEFFICIENTS[3];
+  // this._gainHighW.gain.value = -1 * GAIN_COEFFICIENTS[0];
+  // this._gainHighY.gain.value = -1 * GAIN_COEFFICIENTS[1];
+  // this._gainHighZ.gain.value = -1 * GAIN_COEFFICIENTS[2];
+  // this._gainHighX.gain.value = -1 * GAIN_COEFFICIENTS[3];
+  this._gainHighW.gain.setValueAtTime(-GAIN_COEFFICIENTS[0], 0);
+  this._gainHighY.gain.setValueAtTime(-GAIN_COEFFICIENTS[1], 0);
+  this._gainHighZ.gain.setValueAtTime(-GAIN_COEFFICIENTS[2], 0);
+  this._gainHighX.gain.setValueAtTime(-GAIN_COEFFICIENTS[3], 0);
 
   // Input/output Proxy.
   this.input = this._input;
diff --git a/test/index.html b/test/index.html
index 55d1aaf..2ebb4fb 100644
--- a/test/index.html
+++ b/test/index.html
@@ -30,6 +30,7 @@
   <script>mocha.setup('bdd')</script>
   <script src="test-router.js"></script>
   <script src="test-rotator.js"></script>
+  <script src="test-phasematchedfilter.js"></script>
   <script>mocha.run();</script>
 </body>
 </html>
diff --git a/test/test-phasematchedfilter.js b/test/test-phasematchedfilter.js
new file mode 100644
index 0000000..a41513c
--- /dev/null
+++ b/test/test-phasematchedfilter.js
@@ -0,0 +1,77 @@
+/**
+ * Copyright 2016 Google Inc. All Rights Reserved.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+
+describe('FOAPhaseMatchedFilter', function () {
+
+  var sampleRate = 48000;
+  var renderLength = 128;
+  var context;
+  var testAudioBus;
+
+  // Parameters for the FOA phase matched filter.
+  var crossoverFrequency = 690;
+  var hipassGainCompensation = [-1.4142, -0.8166, -0.8166, -0.8166];
+
+  // A common task for router tests. Create an OAC for rendering.
+  beforeEach(function (done) {
+    context = new OfflineAudioContext(4, renderLength, sampleRate);
+    testAudioBus = new AudioBus(4, renderLength, sampleRate);
+    testAudioBus.fillChannelData([0.25, 0.5, 0.75, 1]);
+    done();
+  });
+
+
+  it('Simulate and verify the phase-matched filter implementation.',
+      function (done) {
+
+        // Generate the expected filter result.
+        var filterCoefs = getDualBandFilterCoefs(
+            crossoverFrequency, sampleRate);
+
+        var hipassBus = new AudioBus(4, renderLength, sampleRate);
+        hipassBus.copyFrom(testAudioBus);
+        hipassBus.processIIRFilter(filterCoefs.hipassB, filterCoefs.hipassA);
+        hipassBus.processGain(hipassGainCompensation);
+
+        var lowpassBus = new AudioBus(4, renderLength, sampleRate);
+        lowpassBus.copyFrom(testAudioBus);
+        lowpassBus.processIIRFilter(filterCoefs.lowpassB, filterCoefs.lowpassA);
+
+        hipassBus.sumFrom(lowpassBus);
+
+        // Generate the actual filter result.
+        var source = context.createBufferSource();
+        source.buffer = testAudioBus.getAudioBuffer(context);
+
+        var dualbandFilter = Omnitone.createFOAPhaseMatchedFilter(context);
+
+        source.connect(dualbandFilter.input);
+        dualbandFilter.output.connect(context.destination);
+
+        source.start();
+
+        context.startRendering().then(function (renderedBuffer) {
+          var actualBus = new AudioBus(4, renderLength, sampleRate);
+          actualBus.copyFromAudioBuffer(renderedBuffer);
+          hipassBus.compareWith(actualBus, 0.01);
+
+          done();
+        });
+      }
+  );
+
+
+});
diff --git a/test/test-setup.js b/test/test-setup.js
index 81772bc..f7b232a 100644
--- a/test/test-setup.js
+++ b/test/test-setup.js
@@ -53,3 +53,139 @@ function isConstantValueOf(channelData, value) {
 
   return Object.keys(mismatches).length === 0;
 };
+
+
+/**
+ * @param  {[type]} crossoverFrequency [description]
+ * @param  {[type]} sampleRate         [description]
+ * @return {[type]}                    [description]
+ */
+function getDualBandFilterCoefs(crossoverFrequency, sampleRate) {
+  var k = Math.tan(Math.PI * crossoverFrequency / sampleRate),
+      k2 = k * k,
+      denominator = k2 + 2 * k + 1;
+
+  return {
+    lowpassA: [1, 2 * (k2 - 1) / denominator, (k2 - 2 * k + 1) / denominator],
+    lowpassB: [k2 / denominator, 2 * k2 / denominator, k2 / denominator],
+    hipassA: [1, 2 * (k2 - 1) / denominator, (k2 - 2 * k + 1) / denominator],
+    hipassB: [1 / denominator, -2 * 1 / denominator, 1 / denominator]
+  };
+}
+
+/**
+ * Kernel processor for IIR filter. (in-place processing)
+ * @param  {Float32Array} channelData A channel data.
+ * @param  {Float32Array} feedforward Feedforward coefficients.
+ * @param  {Float32Array} feedback    Feedback coefficients.
+ */
+function kernel_IIRFIlter (channelData, feedforward, feedback) {
+  var paddingSize = Math.max(feedforward.length, feedback.length);
+  var workSize = channelData.length + paddingSize;
+  var x = new Float32Array(workSize);
+  var y = new Float64Array(workSize);
+
+  x.set(channelData, paddingSize);
+
+  for (var index = paddingSize; index < workSize; ++index) {
+    var yn = 0;
+    for (k = 0; k < feedforward.length; ++k)
+      yn += feedforward[k] * x[index - k];
+    for (k = 0; k < feedback.length; ++k)
+      yn -= feedback[k] * y[index - k];
+    y[index] = yn;
+  }
+
+  channelData.set(y.slice(paddingSize).map(Math.fround));
+}
+
+
+/**
+ * [AudioBus description]
+ * @param {[type]} numberOfChannels [description]
+ * @param {[type]} length           [description]
+ * @param {[type]} sampleRate       [description]
+ */
+function AudioBus (numberOfChannels, length, sampleRate) {
+  this.numberOfChannels = numberOfChannels;
+  this.sampleRate = sampleRate;
+  this.length = length;
+  this.duration = this.length / this.sampleRate;
+
+  this._channelData = [];
+  for (var i = 0; i < this.numberOfChannels; ++i) {
+    this._channelData[i] = new Float32Array(length);
+  }
+}
+
+AudioBus.prototype.getChannelData = function (channel) {
+  return this._channelData[channel];
+};
+
+AudioBus.prototype.getAudioBuffer = function (context) {
+  var audioBuffer = context.createBuffer(
+      this.numberOfChannels, this.length, this.sampleRate);
+
+  for (var channel = 0; channel < this.numberOfChannels; ++channel)
+    audioBuffer.getChannelData(channel).set(this._channelData[channel]);
+
+  return audioBuffer;
+};
+
+AudioBus.prototype.fillChannelData = function (samples) {
+  for (var channel = 0; channel < this.numberOfChannels; ++channel)
+    this._channelData[channel].fill(samples[channel]);
+};
+
+AudioBus.prototype.copyFrom = function (otherAudioBus) {
+  for (var channel = 0; channel < this.numberOfChannels; ++channel)
+    this._channelData[channel].set(otherAudioBus.getChannelData(channel));
+};
+
+AudioBus.prototype.copyFromAudioBuffer = function (audioBuffer) {
+  for (var channel = 0; channel < this.numberOfChannels; ++channel)
+    this._channelData[channel].set(audioBuffer.getChannelData(channel));
+};
+
+AudioBus.prototype.sumFrom = function (otherAudioBus) {
+  for (var channel = 0; channel < this.numberOfChannels; ++channel) {
+    var channelDataA = this._channelData[channel];
+    var channelDataB = otherAudioBus.getChannelData(channel);
+    for (var i = 0; i < this.length; ++i)
+      channelDataA[i] += channelDataB[i];
+  }
+};
+
+AudioBus.prototype.compareWith = function (otherAudioBus, threshold) {
+  for (var channel = 0; channel < this.numberOfChannels; ++channel) {
+    var channelDataA = this._channelData[channel];
+    var channelDataB = otherAudioBus.getChannelData(channel);
+    
+    for (var i = 0; i < this.length; ++i) {
+      var absDiff = Math.abs(channelDataA[i] - channelDataB[i]);
+      if (absDiff > threshold) {
+        console.log('ERROR: at the index ' + i + ' (' 
+            + absDiff + ' > ' + threshold + ').');
+      }
+    }
+  }
+};
+
+AudioBus.prototype.processGain = function (coefficents) {
+  for (var channel = 0; channel < this.numberOfChannels; ++channel) {
+    var channelData = this._channelData[channel];
+    for (var i = 0; i < this.length; ++i)
+      channelData[i] *= coefficents[channel];
+  }
+};
+
+AudioBus.prototype.processIIRFilter = function (feedforward, feedback) {
+  for (var channel = 0; channel < this.numberOfChannels; ++channel)
+    kernel_IIRFIlter(this._channelData[channel], feedforward, feedback);
+};
+
+AudioBus.prototype.print = function () {
+  for (var channel = 0; channel < this.numberOfChannels; ++channel) {
+    console.log(this._channelData[channel]);
+  }
+}

From 28cac716c2644f68b6788f7e56ff010c4039777a Mon Sep 17 00:00:00 2001
From: Hongchan Choi <hongchan@chromium.org>
Date: Mon, 7 Nov 2016 13:12:45 -0800
Subject: [PATCH 2/4] fixed filter issue

---
 build/omnitone.min.js           |  2 +-
 package.json                    |  2 +-
 src/foa-phase-matched-filter.js | 15 +++++----
 src/version.js                  |  2 +-
 test/test-phasematchedfilter.js | 49 +++++++++++++++++++++++----
 test/test-setup.js              | 60 ++++++++++++++++++++-------------
 6 files changed, 90 insertions(+), 40 deletions(-)

diff --git a/build/omnitone.min.js b/build/omnitone.min.js
index 74f320b..272704e 100644
--- a/build/omnitone.min.js
+++ b/build/omnitone.min.js
@@ -13,4 +13,4 @@
 	 * See the License for the specific language governing permissions and
 	 * limitations under the License.
 	 */
-"use strict";i.Omnitone=e(1)},function(t,i,e){"use strict";var n={},s=e(2),o=e(4),a=e(5),h=e(6),c=e(7),r=e(8);n.loadAudioBuffers=function(t,i){return new Promise(function(e,n){new s(t,i,function(t){e(t)},n)})},n.createFOARouter=function(t,i){return new o(t,i)},n.createFOARotator=function(t){return new a(t)},n.createFOAPhaseMatchedFilter=function(t){return new h(t)},n.createFOAVirtualSpeaker=function(t,i){return new c(t,i)},n.createFOADecoder=function(t,i,e){return new r(t,i,e)},t.exports=n},function(t,i,e){"use strict";function n(t,i,e,n,o){this._context=t,this._buffers=new Map,this._loadingTasks={},this._resolve=e,this._reject=n,this._progress=o;for(var a=0;a<i.length;a++){var h=i[a];if(this._loadingTasks.hasOwnProperty(h.name))return void s.log("Duplicated filename when loading: "+h.name);this._loadingTasks[h.name]=0,this._loadAudioFile(h)}}var s=e(3);n.prototype._loadAudioFile=function(t){var i=new XMLHttpRequest;i.open("GET",t.url),i.responseType="arraybuffer";var e=this;i.onload=function(){200===i.status?e._context.decodeAudioData(i.response,function(i){e._done(t.name,i)},function(i){s.log("Decoding failure: "+t.url+" ("+i+")"),e._done(t.name,null)}):(s.log("XHR Error: "+t.url+" ("+i.statusText+")"),e._done(t.name,null))},i.onerror=function(i){s.log("XHR Network failure: "+t.url),e._done(t.name,null)},i.send()},n.prototype._done=function(t,i){this._loadingTasks[t]=null!==i?"loaded":"failed",this._buffers.set(t,i),this._updateProgress(t)},n.prototype._updateProgress=function(t){var i=0,e=0,n=0;for(var s in this._loadingTasks)n++,"loaded"===this._loadingTasks[s]?i++:"failed"===this._loadingTasks[s]&&e++;"function"==typeof this._progress&&this._progress(t,i,n),i===n&&this._resolve(this._buffers),i+e===n&&this._reject(this._buffers)},t.exports=n},function(t,i){"use strict";i.log=function(){window.console.log.apply(window.console,["%c[Omnitone]%c "+Array.prototype.slice.call(arguments).join(" ")+" %c(@"+performance.now().toFixed(2)+"ms)","background: #BBDEFB; color: #FF5722; font-weight: 700","font-weight: 400","color: #AAA"])},i.invertMatrix4=function(t,i){var e=i[0],n=i[1],s=i[2],o=i[3],a=i[4],h=i[5],c=i[6],r=i[7],_=i[8],l=i[9],u=i[10],p=i[11],g=i[12],f=i[13],m=i[14],d=i[15],v=e*h-n*a,x=e*c-s*a,M=e*r-o*a,w=n*c-s*h,y=n*r-o*h,R=s*r-o*c,F=_*f-l*g,A=_*m-u*g,G=_*d-p*g,b=l*m-u*f,H=l*d-p*f,D=u*d-p*m,k=v*D-x*H+M*b+w*G-y*A+R*F;return k?(k=1/k,t[0]=(h*D-c*H+r*b)*k,t[1]=(s*H-n*D-o*b)*k,t[2]=(f*R-m*y+d*w)*k,t[3]=(u*y-l*R-p*w)*k,t[4]=(c*G-a*D-r*A)*k,t[5]=(e*D-s*G+o*A)*k,t[6]=(m*M-g*R-d*x)*k,t[7]=(_*R-u*M+p*x)*k,t[8]=(a*H-h*G+r*F)*k,t[9]=(n*G-e*H-o*F)*k,t[10]=(g*y-f*M+d*v)*k,t[11]=(l*M-_*y-p*v)*k,t[12]=(h*A-a*b-c*F)*k,t[13]=(e*b-n*A+s*F)*k,t[14]=(f*x-g*w-m*v)*k,t[15]=(_*w-l*x+u*v)*k,t):null}},function(t,i){"use strict";function e(t,i){this._context=t,this._splitter=this._context.createChannelSplitter(4),this._merger=this._context.createChannelMerger(4),this._channelMap=i||n,this._splitter.connect(this._merger,0,this._channelMap[0]),this._splitter.connect(this._merger,1,this._channelMap[1]),this._splitter.connect(this._merger,2,this._channelMap[2]),this._splitter.connect(this._merger,3,this._channelMap[3]),this.input=this._splitter,this.output=this._merger}var n=[0,1,2,3];e.prototype.setChannelMap=function(t){t&&(this._channelMap=t,this._splitter.disconnect(),this._splitter.connect(this._merger,0,this._channelMap[0]),this._splitter.connect(this._merger,1,this._channelMap[1]),this._splitter.connect(this._merger,2,this._channelMap[2]),this._splitter.connect(this._merger,3,this._channelMap[3]))},t.exports=e},function(t,i){"use strict";function e(t){this._context=t,this._splitter=this._context.createChannelSplitter(4),this._inY=this._context.createGain(),this._inZ=this._context.createGain(),this._inX=this._context.createGain(),this._m0=this._context.createGain(),this._m1=this._context.createGain(),this._m2=this._context.createGain(),this._m3=this._context.createGain(),this._m4=this._context.createGain(),this._m5=this._context.createGain(),this._m6=this._context.createGain(),this._m7=this._context.createGain(),this._m8=this._context.createGain(),this._outY=this._context.createGain(),this._outZ=this._context.createGain(),this._outX=this._context.createGain(),this._merger=this._context.createChannelMerger(4),this._splitter.connect(this._inY,1),this._splitter.connect(this._inZ,2),this._splitter.connect(this._inX,3),this._inY.gain.value=-1,this._inX.gain.value=-1,this._inY.connect(this._m0),this._inY.connect(this._m1),this._inY.connect(this._m2),this._inZ.connect(this._m3),this._inZ.connect(this._m4),this._inZ.connect(this._m5),this._inX.connect(this._m6),this._inX.connect(this._m7),this._inX.connect(this._m8),this._m0.connect(this._outY),this._m1.connect(this._outZ),this._m2.connect(this._outX),this._m3.connect(this._outY),this._m4.connect(this._outZ),this._m5.connect(this._outX),this._m6.connect(this._outY),this._m7.connect(this._outZ),this._m8.connect(this._outX),this._splitter.connect(this._merger,0,0),this._outY.connect(this._merger,0,1),this._outZ.connect(this._merger,0,2),this._outX.connect(this._merger,0,3),this._outY.gain.value=-1,this._outX.gain.value=-1,this.setRotationMatrix(new Float32Array([1,0,0,0,1,0,0,0,1])),this.input=this._splitter,this.output=this._merger}e.prototype.setRotationMatrix=function(t){this._m0.gain.value=t[0],this._m1.gain.value=t[1],this._m2.gain.value=t[2],this._m3.gain.value=t[3],this._m4.gain.value=t[4],this._m5.gain.value=t[5],this._m6.gain.value=t[6],this._m7.gain.value=t[7],this._m8.gain.value=t[8]},e.prototype.setRotationMatrix4=function(t){this._m0.gain.value=t[0],this._m1.gain.value=t[1],this._m2.gain.value=t[2],this._m3.gain.value=t[4],this._m4.gain.value=t[5],this._m5.gain.value=t[6],this._m6.gain.value=t[8],this._m7.gain.value=t[9],this._m8.gain.value=t[10]},e.prototype.getRotationMatrix=function(){return[this._m0.gain.value,this._m1.gain.value,this._m2.gain.value,this._m3.gain.value,this._m4.gain.value,this._m5.gain.value,this._m6.gain.value,this._m7.gain.value,this._m8.gain.value]},t.exports=e},function(t,i,e){"use strict";function n(t,i){var e=Math.tan(Math.PI*t/i),n=e*e,s=n+2*e+1;return{lowpassA:[1,2*(n-1)/s,(n-2*e+1)/s],lowpassB:[n/s,2*n/s,n/s],hipassA:[1,2*(n-1)/s,(n-2*e+1)/s],hipassB:[1/s,-2/s,1/s]}}function s(t){if(this._context=t,this._input=this._context.createGain(),this._context.createIIRFilter){var i=n(a,this._context.sampleRate);this._lpf=this._context.createIIRFilter(i.lowpassB,i.lowpassA),this._hpf=this._context.createIIRFilter(i.hipassB,i.hipassA)}else o.log("IIR filter is missing. Using Biquad filter instead."),this._lpf=this._context.createBiquadFilter(),this._hpf=this._context.createBiquadFilter(),this._lpf.frequency.value=a,this._hpf.frequency.value=a,this._hpf.type="highpass";this._splitterLow=this._context.createChannelSplitter(4),this._splitterHigh=this._context.createChannelSplitter(4),this._gainHighW=this._context.createGain(),this._gainHighY=this._context.createGain(),this._gainHighZ=this._context.createGain(),this._gainHighX=this._context.createGain(),this._merger=this._context.createChannelMerger(4),this._input.connect(this._hpf),this._hpf.connect(this._splitterHigh),this._splitterHigh.connect(this._gainHighW,0),this._splitterHigh.connect(this._gainHighY,1),this._splitterHigh.connect(this._gainHighZ,2),this._splitterHigh.connect(this._gainHighX,3),this._gainHighW.connect(this._merger,0,0),this._gainHighY.connect(this._merger,0,1),this._gainHighZ.connect(this._merger,0,2),this._gainHighX.connect(this._merger,0,3),this._input.connect(this._lpf),this._lpf.connect(this._splitterLow),this._splitterLow.connect(this._merger,0,0),this._splitterLow.connect(this._merger,0,1),this._splitterLow.connect(this._merger,0,2),this._splitterLow.connect(this._merger,0,3),this._gainHighW.gain.value=-1*h[0],this._gainHighY.gain.value=-1*h[1],this._gainHighZ.gain.value=-1*h[2],this._gainHighX.gain.value=-1*h[3],this.input=this._input,this.output=this._merger}var o=e(3),a=690,h=[1.4142,.8166,.8166,.8166];t.exports=s},function(t,i){"use strict";function e(t,i){if(2!==i.IR.numberOfChannels)throw"IR does not have 2 channels. cannot proceed.";this._active=!1,this._context=t,this._input=this._context.createChannelSplitter(4),this._cW=this._context.createGain(),this._cY=this._context.createGain(),this._cZ=this._context.createGain(),this._cX=this._context.createGain(),this._convolver=this._context.createConvolver(),this._gain=this._context.createGain(),this._input.connect(this._cW,0),this._input.connect(this._cY,1),this._input.connect(this._cZ,2),this._input.connect(this._cX,3),this._cW.connect(this._convolver),this._cY.connect(this._convolver),this._cZ.connect(this._convolver),this._cX.connect(this._convolver),this._convolver.connect(this._gain),this._gain.connect(this._context.destination),this.enable(),this._convolver.normalize=!1,this._convolver.buffer=i.IR,this._gain.gain.value=i.gain,this._cW.gain.value=i.coefficients[0],this._cY.gain.value=i.coefficients[1],this._cZ.gain.value=i.coefficients[2],this._cX.gain.value=i.coefficients[3],this.input=this._input}e.prototype.enable=function(){this._gain.connect(this._context.destination),this._active=!0},e.prototype.disable=function(){this._gain.disconnect(),this._active=!1},t.exports=e},function(t,i,e){"use strict";function n(t,i,e){this._isDecoderReady=!1,this._context=t,this._videoElement=i,this._decodingMode="ambisonic",this._postGainDB=p,this._HRTFSetUrl=u,this._channelMap=g,e&&(e.postGainDB&&(this._postGainDB=e.postGainDB),e.HRTFSetUrl&&(this._HRTFSetUrl=e.HRTFSetUrl),e.channelMap&&(this._channelMap=e.channelMap)),this._speakerData=[];for(var n=0;n<r.length;++n)this._speakerData.push({name:r[n].name,url:this._HRTFSetUrl+"/"+r[n].url,coef:r[n].coef});this._tempMatrix4=new Float32Array(16)}var s=e(2),o=e(4),a=e(5),h=e(6),c=e(7),r=e(9),_=e(3),l=e(10),u="https://raw.githubusercontent.com/google/spatial-media/master/support/hrtfs/cube/",p=0,g=[0,1,2,3];n.prototype.initialize=function(){_.log("Version: "+l),_.log("Initializing... (mode: "+this._decodingMode+")");var t=this._channelMap.toString();t!==g.toString()&&_.log("Remapping channels ([0,1,2,3] -> ["+t+"])"),this._audioElementSource=this._context.createMediaElementSource(this._videoElement),this._foaRouter=new o(this._context,this._channelMap),this._foaRotator=new a(this._context),this._foaPhaseMatchedFilter=new h(this._context),this._audioElementSource.connect(this._foaRouter.input),this._foaRouter.output.connect(this._foaRotator.input),this._foaRotator.output.connect(this._foaPhaseMatchedFilter.input),this._foaVirtualSpeakers=[],this._bypass=this._context.createGain(),this._audioElementSource.connect(this._bypass);var i=Math.pow(10,this._postGainDB/20);_.log("Gain compensation: "+i+" ("+this._postGainDB+"dB)");var e=this;return new Promise(function(t,n){new s(e._context,e._speakerData,function(n){for(var s=0;s<e._speakerData.length;++s)e._foaVirtualSpeakers[s]=new c(e._context,{coefficients:e._speakerData[s].coef,IR:n.get(e._speakerData[s].name),gain:i}),e._foaPhaseMatchedFilter.output.connect(e._foaVirtualSpeakers[s].input);e.setMode(e._decodingMode),e._isDecoderReady=!0,_.log("HRTF IRs are loaded successfully. The decoder is ready."),t()},n)})},n.prototype.setRotationMatrix=function(t){this._foaRotator.setRotationMatrix(t)},n.prototype.setRotationMatrixFromCamera=function(t){_.invertMatrix4(this._tempMatrix4,t.elements),this._foaRotator.setRotationMatrix4(this._tempMatrix4)},n.prototype.setMode=function(t){if(t!==this._decodingMode){switch(t){case"bypass":this._decodingMode="bypass";for(var i=0;i<this._foaVirtualSpeakers.length;++i)this._foaVirtualSpeakers[i].disable();this._bypass.connect(this._context.destination);break;case"ambisonic":this._decodingMode="ambisonic";for(var i=0;i<this._foaVirtualSpeakers.length;++i)this._foaVirtualSpeakers[i].enable();this._bypass.disconnect();break;case"off":this._decodingMode="off";for(var i=0;i<this._foaVirtualSpeakers.length;++i)this._foaVirtualSpeakers[i].disable();this._bypass.disconnect()}_.log("Decoding mode changed. ("+t+")")}},t.exports=n},function(t,i){var e=[{name:"E35.26_A135",url:"E35.26_A135_D1.4.wav",gainFactor:1,coef:[.125,.216495,.21653,-.216495]},{name:"E35.26_A-135",url:"E35.26_A-135_D1.4.wav",gainFactor:1,coef:[.125,-.216495,.21653,-.216495]},{name:"E-35.26_A135",url:"E-35.26_A135_D1.4.wav",gainFactor:1,coef:[.125,.216495,-.21653,-.216495]},{name:"E-35.26_A-135",url:"E-35.26_A-135_D1.4.wav",gainFactor:1,coef:[.125,-.216495,-.21653,-.216495]},{name:"E35.26_A45",url:"E35.26_A45_D1.4.wav",gainFactor:1,coef:[.125,.216495,.21653,.216495]},{name:"E35.26_A-45",url:"E35.26_A-45_D1.4.wav",gainFactor:1,coef:[.125,-.216495,.21653,.216495]},{name:"E-35.26_A45",url:"E-35.26_A45_D1.4.wav",gainFactor:1,coef:[.125,.216495,-.21653,.216495]},{name:"E-35.26_A-45",url:"E-35.26_A-45_D1.4.wav",gainFactor:1,coef:[.125,-.216495,-.21653,.216495]}];t.exports=e},function(t,i){"use strict";t.exports="0.1.7"}])});
\ No newline at end of file
+"use strict";i.Omnitone=e(1)},function(t,i,e){"use strict";var n={},s=e(2),o=e(4),a=e(5),h=e(6),c=e(7),r=e(8);n.loadAudioBuffers=function(t,i){return new Promise(function(e,n){new s(t,i,function(t){e(t)},n)})},n.createFOARouter=function(t,i){return new o(t,i)},n.createFOARotator=function(t){return new a(t)},n.createFOAPhaseMatchedFilter=function(t){return new h(t)},n.createFOAVirtualSpeaker=function(t,i){return new c(t,i)},n.createFOADecoder=function(t,i,e){return new r(t,i,e)},t.exports=n},function(t,i,e){"use strict";function n(t,i,e,n,o){this._context=t,this._buffers=new Map,this._loadingTasks={},this._resolve=e,this._reject=n,this._progress=o;for(var a=0;a<i.length;a++){var h=i[a];if(this._loadingTasks.hasOwnProperty(h.name))return void s.log("Duplicated filename when loading: "+h.name);this._loadingTasks[h.name]=0,this._loadAudioFile(h)}}var s=e(3);n.prototype._loadAudioFile=function(t){var i=new XMLHttpRequest;i.open("GET",t.url),i.responseType="arraybuffer";var e=this;i.onload=function(){200===i.status?e._context.decodeAudioData(i.response,function(i){e._done(t.name,i)},function(i){s.log("Decoding failure: "+t.url+" ("+i+")"),e._done(t.name,null)}):(s.log("XHR Error: "+t.url+" ("+i.statusText+")"),e._done(t.name,null))},i.onerror=function(i){s.log("XHR Network failure: "+t.url),e._done(t.name,null)},i.send()},n.prototype._done=function(t,i){this._loadingTasks[t]=null!==i?"loaded":"failed",this._buffers.set(t,i),this._updateProgress(t)},n.prototype._updateProgress=function(t){var i=0,e=0,n=0;for(var s in this._loadingTasks)n++,"loaded"===this._loadingTasks[s]?i++:"failed"===this._loadingTasks[s]&&e++;"function"==typeof this._progress&&this._progress(t,i,n),i===n&&this._resolve(this._buffers),i+e===n&&this._reject(this._buffers)},t.exports=n},function(t,i){"use strict";i.log=function(){window.console.log.apply(window.console,["%c[Omnitone]%c "+Array.prototype.slice.call(arguments).join(" ")+" %c(@"+performance.now().toFixed(2)+"ms)","background: #BBDEFB; color: #FF5722; font-weight: 700","font-weight: 400","color: #AAA"])},i.invertMatrix4=function(t,i){var e=i[0],n=i[1],s=i[2],o=i[3],a=i[4],h=i[5],c=i[6],r=i[7],_=i[8],l=i[9],u=i[10],p=i[11],g=i[12],f=i[13],m=i[14],d=i[15],v=e*h-n*a,x=e*c-s*a,M=e*r-o*a,w=n*c-s*h,y=n*r-o*h,R=s*r-o*c,A=_*f-l*g,F=_*m-u*g,G=_*d-p*g,b=l*m-u*f,H=l*d-p*f,D=u*d-p*m,k=v*D-x*H+M*b+w*G-y*F+R*A;return k?(k=1/k,t[0]=(h*D-c*H+r*b)*k,t[1]=(s*H-n*D-o*b)*k,t[2]=(f*R-m*y+d*w)*k,t[3]=(u*y-l*R-p*w)*k,t[4]=(c*G-a*D-r*F)*k,t[5]=(e*D-s*G+o*F)*k,t[6]=(m*M-g*R-d*x)*k,t[7]=(_*R-u*M+p*x)*k,t[8]=(a*H-h*G+r*A)*k,t[9]=(n*G-e*H-o*A)*k,t[10]=(g*y-f*M+d*v)*k,t[11]=(l*M-_*y-p*v)*k,t[12]=(h*F-a*b-c*A)*k,t[13]=(e*b-n*F+s*A)*k,t[14]=(f*x-g*w-m*v)*k,t[15]=(_*w-l*x+u*v)*k,t):null}},function(t,i){"use strict";function e(t,i){this._context=t,this._splitter=this._context.createChannelSplitter(4),this._merger=this._context.createChannelMerger(4),this._channelMap=i||n,this._splitter.connect(this._merger,0,this._channelMap[0]),this._splitter.connect(this._merger,1,this._channelMap[1]),this._splitter.connect(this._merger,2,this._channelMap[2]),this._splitter.connect(this._merger,3,this._channelMap[3]),this.input=this._splitter,this.output=this._merger}var n=[0,1,2,3];e.prototype.setChannelMap=function(t){t&&(this._channelMap=t,this._splitter.disconnect(),this._splitter.connect(this._merger,0,this._channelMap[0]),this._splitter.connect(this._merger,1,this._channelMap[1]),this._splitter.connect(this._merger,2,this._channelMap[2]),this._splitter.connect(this._merger,3,this._channelMap[3]))},t.exports=e},function(t,i){"use strict";function e(t){this._context=t,this._splitter=this._context.createChannelSplitter(4),this._inY=this._context.createGain(),this._inZ=this._context.createGain(),this._inX=this._context.createGain(),this._m0=this._context.createGain(),this._m1=this._context.createGain(),this._m2=this._context.createGain(),this._m3=this._context.createGain(),this._m4=this._context.createGain(),this._m5=this._context.createGain(),this._m6=this._context.createGain(),this._m7=this._context.createGain(),this._m8=this._context.createGain(),this._outY=this._context.createGain(),this._outZ=this._context.createGain(),this._outX=this._context.createGain(),this._merger=this._context.createChannelMerger(4),this._splitter.connect(this._inY,1),this._splitter.connect(this._inZ,2),this._splitter.connect(this._inX,3),this._inY.gain.value=-1,this._inX.gain.value=-1,this._inY.connect(this._m0),this._inY.connect(this._m1),this._inY.connect(this._m2),this._inZ.connect(this._m3),this._inZ.connect(this._m4),this._inZ.connect(this._m5),this._inX.connect(this._m6),this._inX.connect(this._m7),this._inX.connect(this._m8),this._m0.connect(this._outY),this._m1.connect(this._outZ),this._m2.connect(this._outX),this._m3.connect(this._outY),this._m4.connect(this._outZ),this._m5.connect(this._outX),this._m6.connect(this._outY),this._m7.connect(this._outZ),this._m8.connect(this._outX),this._splitter.connect(this._merger,0,0),this._outY.connect(this._merger,0,1),this._outZ.connect(this._merger,0,2),this._outX.connect(this._merger,0,3),this._outY.gain.value=-1,this._outX.gain.value=-1,this.setRotationMatrix(new Float32Array([1,0,0,0,1,0,0,0,1])),this.input=this._splitter,this.output=this._merger}e.prototype.setRotationMatrix=function(t){this._m0.gain.value=t[0],this._m1.gain.value=t[1],this._m2.gain.value=t[2],this._m3.gain.value=t[3],this._m4.gain.value=t[4],this._m5.gain.value=t[5],this._m6.gain.value=t[6],this._m7.gain.value=t[7],this._m8.gain.value=t[8]},e.prototype.setRotationMatrix4=function(t){this._m0.gain.value=t[0],this._m1.gain.value=t[1],this._m2.gain.value=t[2],this._m3.gain.value=t[4],this._m4.gain.value=t[5],this._m5.gain.value=t[6],this._m6.gain.value=t[8],this._m7.gain.value=t[9],this._m8.gain.value=t[10]},e.prototype.getRotationMatrix=function(){return[this._m0.gain.value,this._m1.gain.value,this._m2.gain.value,this._m3.gain.value,this._m4.gain.value,this._m5.gain.value,this._m6.gain.value,this._m7.gain.value,this._m8.gain.value]},t.exports=e},function(t,i,e){"use strict";function n(t,i){var e=Math.tan(Math.PI*t/i),n=e*e,s=n+2*e+1;return{lowpassA:[1,2*(n-1)/s,(n-2*e+1)/s],lowpassB:[n/s,2*n/s,n/s],hipassA:[1,2*(n-1)/s,(n-2*e+1)/s],hipassB:[1/s,-2/s,1/s]}}function s(t){if(this._context=t,this._input=this._context.createGain(),this._context.createIIRFilter){var i=n(a,this._context.sampleRate);this._lpf=this._context.createIIRFilter(i.lowpassB,i.lowpassA),this._hpf=this._context.createIIRFilter(i.hipassB,i.hipassA)}else o.log("IIR filter is missing. Using Biquad filter instead."),this._lpf=this._context.createBiquadFilter(),this._hpf=this._context.createBiquadFilter(),this._lpf.frequency.value=a,this._hpf.frequency.value=a,this._hpf.type="highpass";this._splitterLow=this._context.createChannelSplitter(4),this._splitterHigh=this._context.createChannelSplitter(4),this._gainHighW=this._context.createGain(),this._gainHighY=this._context.createGain(),this._gainHighZ=this._context.createGain(),this._gainHighX=this._context.createGain(),this._merger=this._context.createChannelMerger(4),this._input.connect(this._hpf),this._hpf.connect(this._splitterHigh),this._splitterHigh.connect(this._gainHighW,0),this._splitterHigh.connect(this._gainHighY,1),this._splitterHigh.connect(this._gainHighZ,2),this._splitterHigh.connect(this._gainHighX,3),this._gainHighW.connect(this._merger,0,0),this._gainHighY.connect(this._merger,0,1),this._gainHighZ.connect(this._merger,0,2),this._gainHighX.connect(this._merger,0,3),this._input.connect(this._lpf),this._lpf.connect(this._splitterLow),this._splitterLow.connect(this._merger,0,0),this._splitterLow.connect(this._merger,1,1),this._splitterLow.connect(this._merger,2,2),this._splitterLow.connect(this._merger,3,3);var e=this._context.currentTime;this._gainHighW.gain.setValueAtTime(-1*h[0],e),this._gainHighY.gain.setValueAtTime(-1*h[1],e),this._gainHighZ.gain.setValueAtTime(-1*h[2],e),this._gainHighX.gain.setValueAtTime(-1*h[3],e),this.input=this._input,this.output=this._merger}var o=e(3),a=690,h=[1.4142,.8166,.8166,.8166];t.exports=s},function(t,i){"use strict";function e(t,i){if(2!==i.IR.numberOfChannels)throw"IR does not have 2 channels. cannot proceed.";this._active=!1,this._context=t,this._input=this._context.createChannelSplitter(4),this._cW=this._context.createGain(),this._cY=this._context.createGain(),this._cZ=this._context.createGain(),this._cX=this._context.createGain(),this._convolver=this._context.createConvolver(),this._gain=this._context.createGain(),this._input.connect(this._cW,0),this._input.connect(this._cY,1),this._input.connect(this._cZ,2),this._input.connect(this._cX,3),this._cW.connect(this._convolver),this._cY.connect(this._convolver),this._cZ.connect(this._convolver),this._cX.connect(this._convolver),this._convolver.connect(this._gain),this._gain.connect(this._context.destination),this.enable(),this._convolver.normalize=!1,this._convolver.buffer=i.IR,this._gain.gain.value=i.gain,this._cW.gain.value=i.coefficients[0],this._cY.gain.value=i.coefficients[1],this._cZ.gain.value=i.coefficients[2],this._cX.gain.value=i.coefficients[3],this.input=this._input}e.prototype.enable=function(){this._gain.connect(this._context.destination),this._active=!0},e.prototype.disable=function(){this._gain.disconnect(),this._active=!1},t.exports=e},function(t,i,e){"use strict";function n(t,i,e){this._isDecoderReady=!1,this._context=t,this._videoElement=i,this._decodingMode="ambisonic",this._postGainDB=p,this._HRTFSetUrl=u,this._channelMap=g,e&&(e.postGainDB&&(this._postGainDB=e.postGainDB),e.HRTFSetUrl&&(this._HRTFSetUrl=e.HRTFSetUrl),e.channelMap&&(this._channelMap=e.channelMap)),this._speakerData=[];for(var n=0;n<r.length;++n)this._speakerData.push({name:r[n].name,url:this._HRTFSetUrl+"/"+r[n].url,coef:r[n].coef});this._tempMatrix4=new Float32Array(16)}var s=e(2),o=e(4),a=e(5),h=e(6),c=e(7),r=e(9),_=e(3),l=e(10),u="https://raw.githubusercontent.com/google/spatial-media/master/support/hrtfs/cube/",p=0,g=[0,1,2,3];n.prototype.initialize=function(){_.log("Version: "+l),_.log("Initializing... (mode: "+this._decodingMode+")");var t=this._channelMap.toString();t!==g.toString()&&_.log("Remapping channels ([0,1,2,3] -> ["+t+"])"),this._audioElementSource=this._context.createMediaElementSource(this._videoElement),this._foaRouter=new o(this._context,this._channelMap),this._foaRotator=new a(this._context),this._foaPhaseMatchedFilter=new h(this._context),this._audioElementSource.connect(this._foaRouter.input),this._foaRouter.output.connect(this._foaRotator.input),this._foaRotator.output.connect(this._foaPhaseMatchedFilter.input),this._foaVirtualSpeakers=[],this._bypass=this._context.createGain(),this._audioElementSource.connect(this._bypass);var i=Math.pow(10,this._postGainDB/20);_.log("Gain compensation: "+i+" ("+this._postGainDB+"dB)");var e=this;return new Promise(function(t,n){new s(e._context,e._speakerData,function(n){for(var s=0;s<e._speakerData.length;++s)e._foaVirtualSpeakers[s]=new c(e._context,{coefficients:e._speakerData[s].coef,IR:n.get(e._speakerData[s].name),gain:i}),e._foaPhaseMatchedFilter.output.connect(e._foaVirtualSpeakers[s].input);e.setMode(e._decodingMode),e._isDecoderReady=!0,_.log("HRTF IRs are loaded successfully. The decoder is ready."),t()},n)})},n.prototype.setRotationMatrix=function(t){this._foaRotator.setRotationMatrix(t)},n.prototype.setRotationMatrixFromCamera=function(t){_.invertMatrix4(this._tempMatrix4,t.elements),this._foaRotator.setRotationMatrix4(this._tempMatrix4)},n.prototype.setMode=function(t){if(t!==this._decodingMode){switch(t){case"bypass":this._decodingMode="bypass";for(var i=0;i<this._foaVirtualSpeakers.length;++i)this._foaVirtualSpeakers[i].disable();this._bypass.connect(this._context.destination);break;case"ambisonic":this._decodingMode="ambisonic";for(var i=0;i<this._foaVirtualSpeakers.length;++i)this._foaVirtualSpeakers[i].enable();this._bypass.disconnect();break;case"off":this._decodingMode="off";for(var i=0;i<this._foaVirtualSpeakers.length;++i)this._foaVirtualSpeakers[i].disable();this._bypass.disconnect()}_.log("Decoding mode changed. ("+t+")")}},t.exports=n},function(t,i){var e=[{name:"E35.26_A135",url:"E35.26_A135_D1.4.wav",gainFactor:1,coef:[.125,.216495,.21653,-.216495]},{name:"E35.26_A-135",url:"E35.26_A-135_D1.4.wav",gainFactor:1,coef:[.125,-.216495,.21653,-.216495]},{name:"E-35.26_A135",url:"E-35.26_A135_D1.4.wav",gainFactor:1,coef:[.125,.216495,-.21653,-.216495]},{name:"E-35.26_A-135",url:"E-35.26_A-135_D1.4.wav",gainFactor:1,coef:[.125,-.216495,-.21653,-.216495]},{name:"E35.26_A45",url:"E35.26_A45_D1.4.wav",gainFactor:1,coef:[.125,.216495,.21653,.216495]},{name:"E35.26_A-45",url:"E35.26_A-45_D1.4.wav",gainFactor:1,coef:[.125,-.216495,.21653,.216495]},{name:"E-35.26_A45",url:"E-35.26_A45_D1.4.wav",gainFactor:1,coef:[.125,.216495,-.21653,.216495]},{name:"E-35.26_A-45",url:"E-35.26_A-45_D1.4.wav",gainFactor:1,coef:[.125,-.216495,-.21653,.216495]}];t.exports=e},function(t,i){"use strict";t.exports="0.1.7"}])});
\ No newline at end of file
diff --git a/package.json b/package.json
index ae27428..adf8cbc 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "omnitone",
-  "version": "0.1.7",
+  "version": "0.1.8",
   "description": "Spatial Audio Decoder in Web Audio API",
   "main": "src/main.js",
   "keywords": [
diff --git a/src/foa-phase-matched-filter.js b/src/foa-phase-matched-filter.js
index 5f6bed9..69d60c0 100644
--- a/src/foa-phase-matched-filter.js
+++ b/src/foa-phase-matched-filter.js
@@ -89,9 +89,9 @@ function FOAPhaseMatchedFilter (context) {
   this._input.connect(this._lpf);
   this._lpf.connect(this._splitterLow);
   this._splitterLow.connect(this._merger, 0, 0);
-  this._splitterLow.connect(this._merger, 0, 1);
-  this._splitterLow.connect(this._merger, 0, 2);
-  this._splitterLow.connect(this._merger, 0, 3);
+  this._splitterLow.connect(this._merger, 1, 1);
+  this._splitterLow.connect(this._merger, 2, 2);
+  this._splitterLow.connect(this._merger, 3, 3);
 
   // Apply gain correction to hi-passed pressure and velocity components:
   // Inverting sign is necessary as the low-passed and high-passed portion are
@@ -100,10 +100,11 @@ function FOAPhaseMatchedFilter (context) {
   // this._gainHighY.gain.value = -1 * GAIN_COEFFICIENTS[1];
   // this._gainHighZ.gain.value = -1 * GAIN_COEFFICIENTS[2];
   // this._gainHighX.gain.value = -1 * GAIN_COEFFICIENTS[3];
-  this._gainHighW.gain.setValueAtTime(-GAIN_COEFFICIENTS[0], 0);
-  this._gainHighY.gain.setValueAtTime(-GAIN_COEFFICIENTS[1], 0);
-  this._gainHighZ.gain.setValueAtTime(-GAIN_COEFFICIENTS[2], 0);
-  this._gainHighX.gain.setValueAtTime(-GAIN_COEFFICIENTS[3], 0);
+  var now = this._context.currentTime;
+  this._gainHighW.gain.setValueAtTime(-1 * GAIN_COEFFICIENTS[0], now);
+  this._gainHighY.gain.setValueAtTime(-1 * GAIN_COEFFICIENTS[1], now);
+  this._gainHighZ.gain.setValueAtTime(-1 * GAIN_COEFFICIENTS[2], now);
+  this._gainHighX.gain.setValueAtTime(-1 * GAIN_COEFFICIENTS[3], now);
 
   // Input/output Proxy.
   this.input = this._input;
diff --git a/src/version.js b/src/version.js
index 3412f7d..75f3745 100644
--- a/src/version.js
+++ b/src/version.js
@@ -23,4 +23,4 @@
  * Omnitone library version
  * @type {String}
  */
-module.exports = '0.1.7';
+module.exports = '0.1.8';
diff --git a/test/test-phasematchedfilter.js b/test/test-phasematchedfilter.js
index a41513c..0729f5d 100644
--- a/test/test-phasematchedfilter.js
+++ b/test/test-phasematchedfilter.js
@@ -15,16 +15,18 @@
 
 
 describe('FOAPhaseMatchedFilter', function () {
+  // Test threshold. Approximately -140dBFS.
+  var TEST_THRESHOLD = 1.0e-7;
+
+  // Parameters for the FOA phase matched filter.
+  var crossoverFrequency = 690;
+  var hipassGainCompensation = [-1.4142, -0.8166, -0.8166, -0.8166];
 
   var sampleRate = 48000;
   var renderLength = 128;
   var context;
   var testAudioBus;
 
-  // Parameters for the FOA phase matched filter.
-  var crossoverFrequency = 690;
-  var hipassGainCompensation = [-1.4142, -0.8166, -0.8166, -0.8166];
-
   // A common task for router tests. Create an OAC for rendering.
   beforeEach(function (done) {
     context = new OfflineAudioContext(4, renderLength, sampleRate);
@@ -34,9 +36,43 @@ describe('FOAPhaseMatchedFilter', function () {
   });
 
 
+  // Testing IIR filter implementation in the browser. (if applicable)
+  it('Testing the IIR filter implementation.', function (done) {
+      expect(typeof context.createIIRFilter).to.equal('function');
+
+      var filterCoefs = getDualBandFilterCoefs(
+          crossoverFrequency, sampleRate);
+
+      var expectedBus = new AudioBus(4, renderLength, sampleRate);
+      expectedBus.copyFrom(testAudioBus);
+      expectedBus.processIIRFilter(
+          filterCoefs.lowpassB, filterCoefs.lowpassA);
+
+      var source = context.createBufferSource();
+      source.buffer = testAudioBus.getAudioBuffer(context);
+      var filter = context.createIIRFilter(
+          filterCoefs.lowpassB, filterCoefs.lowpassA);
+
+      source.connect(filter);
+      filter.connect(context.destination);
+      source.start();
+
+      context.startRendering().then(function (renderedBuffer) {
+        var actualBus = new AudioBus(4, renderLength, sampleRate);
+        actualBus.copyFromAudioBuffer(renderedBuffer);
+        var result = expectedBus.compareWith(actualBus, 0.0);
+        expect(result).to.equal(true);
+
+        done();
+      });
+    }
+  );
+
+
+  // Create the expected result from the JS-version of dual band filter, and
+  // compare with the FOAPhaseMatchedFilter result.
   it('Simulate and verify the phase-matched filter implementation.',
       function (done) {
-
         // Generate the expected filter result.
         var filterCoefs = getDualBandFilterCoefs(
             crossoverFrequency, sampleRate);
@@ -66,7 +102,8 @@ describe('FOAPhaseMatchedFilter', function () {
         context.startRendering().then(function (renderedBuffer) {
           var actualBus = new AudioBus(4, renderLength, sampleRate);
           actualBus.copyFromAudioBuffer(renderedBuffer);
-          hipassBus.compareWith(actualBus, 0.01);
+          var result = hipassBus.compareWith(actualBus, TEST_THRESHOLD);
+          expect(result).to.equal(true);
 
           done();
         });
diff --git a/test/test-setup.js b/test/test-setup.js
index f7b232a..273c6f2 100644
--- a/test/test-setup.js
+++ b/test/test-setup.js
@@ -56,9 +56,12 @@ function isConstantValueOf(channelData, value) {
 
 
 /**
- * @param  {[type]} crossoverFrequency [description]
- * @param  {[type]} sampleRate         [description]
- * @return {[type]}                    [description]
+ * Generate the filter coefficients for the phase matched dual band filter.
+ * @param  {NUmber} crossoverFrequency Filter crossover frequency.
+ * @param  {NUmber} sampleRate         Operating sample rate.
+ * @return {Object}                    Filter coefficients.
+ *                                     { lowpassA, lowpassB, hipassA, hipassB }
+ *                                     (where B is feedforward, A is feedback.)
  */
 function getDualBandFilterCoefs(crossoverFrequency, sampleRate) {
   var k = Math.tan(Math.PI * crossoverFrequency / sampleRate),
@@ -101,10 +104,10 @@ function kernel_IIRFIlter (channelData, feedforward, feedback) {
 
 
 /**
- * [AudioBus description]
- * @param {[type]} numberOfChannels [description]
- * @param {[type]} length           [description]
- * @param {[type]} sampleRate       [description]
+ * A collection of Float32Array as AudioBus abstraction.
+ * @param {Number} numberOfChannels   Number of channels.
+ * @param {Number} length             Buffer length in samples.
+ * @param {Number} sampleRate         Operating sample rate.
  */
 function AudioBus (numberOfChannels, length, sampleRate) {
   this.numberOfChannels = numberOfChannels;
@@ -156,21 +159,6 @@ AudioBus.prototype.sumFrom = function (otherAudioBus) {
   }
 };
 
-AudioBus.prototype.compareWith = function (otherAudioBus, threshold) {
-  for (var channel = 0; channel < this.numberOfChannels; ++channel) {
-    var channelDataA = this._channelData[channel];
-    var channelDataB = otherAudioBus.getChannelData(channel);
-    
-    for (var i = 0; i < this.length; ++i) {
-      var absDiff = Math.abs(channelDataA[i] - channelDataB[i]);
-      if (absDiff > threshold) {
-        console.log('ERROR: at the index ' + i + ' (' 
-            + absDiff + ' > ' + threshold + ').');
-      }
-    }
-  }
-};
-
 AudioBus.prototype.processGain = function (coefficents) {
   for (var channel = 0; channel < this.numberOfChannels; ++channel) {
     var channelData = this._channelData[channel];
@@ -184,8 +172,32 @@ AudioBus.prototype.processIIRFilter = function (feedforward, feedback) {
     kernel_IIRFIlter(this._channelData[channel], feedforward, feedback);
 };
 
-AudioBus.prototype.print = function () {
+AudioBus.prototype.compareWith = function (otherAudioBus, threshold) {
+  var passed = true;
+
+  for (var channel = 0; channel < this.numberOfChannels; ++channel) {
+    var channelDataA = this._channelData[channel];
+    var channelDataB = otherAudioBus.getChannelData(channel);
+
+    for (var i = 0; i < this.length; ++i) {
+      var absDiff = Math.abs(channelDataA[i] - channelDataB[i]);
+      if (absDiff > threshold) {
+        console.log('ERROR: at the index ' + i + ' (' + absDiff + ' > '
+            + threshold + ').');
+        passed = false;
+      }
+    }
+  }
+
+  return passed;
+};
+
+AudioBus.prototype.print = function (begin, end) {
+  begin = (begin || 0);
+  end = (end || this.length);
+  console.log('AudioBus: <' + begin + ' ~ ' + end + '>');
   for (var channel = 0; channel < this.numberOfChannels; ++channel) {
-    console.log(this._channelData[channel]);
+    console.log(channel
+        + ' => [' + this._channelData[channel].subarray(begin, end) + ']');
   }
 }

From cc01a7cca067e81ffdc9dd40a752a61e74d2c2a1 Mon Sep 17 00:00:00 2001
From: Hongchan Choi <hongchan@chromium.org>
Date: Mon, 7 Nov 2016 13:13:17 -0800
Subject: [PATCH 3/4] rebuild files for 0.1.8

---
 build/omnitone.min.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/build/omnitone.min.js b/build/omnitone.min.js
index 272704e..804025e 100644
--- a/build/omnitone.min.js
+++ b/build/omnitone.min.js
@@ -13,4 +13,4 @@
 	 * See the License for the specific language governing permissions and
 	 * limitations under the License.
 	 */
-"use strict";i.Omnitone=e(1)},function(t,i,e){"use strict";var n={},s=e(2),o=e(4),a=e(5),h=e(6),c=e(7),r=e(8);n.loadAudioBuffers=function(t,i){return new Promise(function(e,n){new s(t,i,function(t){e(t)},n)})},n.createFOARouter=function(t,i){return new o(t,i)},n.createFOARotator=function(t){return new a(t)},n.createFOAPhaseMatchedFilter=function(t){return new h(t)},n.createFOAVirtualSpeaker=function(t,i){return new c(t,i)},n.createFOADecoder=function(t,i,e){return new r(t,i,e)},t.exports=n},function(t,i,e){"use strict";function n(t,i,e,n,o){this._context=t,this._buffers=new Map,this._loadingTasks={},this._resolve=e,this._reject=n,this._progress=o;for(var a=0;a<i.length;a++){var h=i[a];if(this._loadingTasks.hasOwnProperty(h.name))return void s.log("Duplicated filename when loading: "+h.name);this._loadingTasks[h.name]=0,this._loadAudioFile(h)}}var s=e(3);n.prototype._loadAudioFile=function(t){var i=new XMLHttpRequest;i.open("GET",t.url),i.responseType="arraybuffer";var e=this;i.onload=function(){200===i.status?e._context.decodeAudioData(i.response,function(i){e._done(t.name,i)},function(i){s.log("Decoding failure: "+t.url+" ("+i+")"),e._done(t.name,null)}):(s.log("XHR Error: "+t.url+" ("+i.statusText+")"),e._done(t.name,null))},i.onerror=function(i){s.log("XHR Network failure: "+t.url),e._done(t.name,null)},i.send()},n.prototype._done=function(t,i){this._loadingTasks[t]=null!==i?"loaded":"failed",this._buffers.set(t,i),this._updateProgress(t)},n.prototype._updateProgress=function(t){var i=0,e=0,n=0;for(var s in this._loadingTasks)n++,"loaded"===this._loadingTasks[s]?i++:"failed"===this._loadingTasks[s]&&e++;"function"==typeof this._progress&&this._progress(t,i,n),i===n&&this._resolve(this._buffers),i+e===n&&this._reject(this._buffers)},t.exports=n},function(t,i){"use strict";i.log=function(){window.console.log.apply(window.console,["%c[Omnitone]%c "+Array.prototype.slice.call(arguments).join(" ")+" %c(@"+performance.now().toFixed(2)+"ms)","background: #BBDEFB; color: #FF5722; font-weight: 700","font-weight: 400","color: #AAA"])},i.invertMatrix4=function(t,i){var e=i[0],n=i[1],s=i[2],o=i[3],a=i[4],h=i[5],c=i[6],r=i[7],_=i[8],l=i[9],u=i[10],p=i[11],g=i[12],f=i[13],m=i[14],d=i[15],v=e*h-n*a,x=e*c-s*a,M=e*r-o*a,w=n*c-s*h,y=n*r-o*h,R=s*r-o*c,A=_*f-l*g,F=_*m-u*g,G=_*d-p*g,b=l*m-u*f,H=l*d-p*f,D=u*d-p*m,k=v*D-x*H+M*b+w*G-y*F+R*A;return k?(k=1/k,t[0]=(h*D-c*H+r*b)*k,t[1]=(s*H-n*D-o*b)*k,t[2]=(f*R-m*y+d*w)*k,t[3]=(u*y-l*R-p*w)*k,t[4]=(c*G-a*D-r*F)*k,t[5]=(e*D-s*G+o*F)*k,t[6]=(m*M-g*R-d*x)*k,t[7]=(_*R-u*M+p*x)*k,t[8]=(a*H-h*G+r*A)*k,t[9]=(n*G-e*H-o*A)*k,t[10]=(g*y-f*M+d*v)*k,t[11]=(l*M-_*y-p*v)*k,t[12]=(h*F-a*b-c*A)*k,t[13]=(e*b-n*F+s*A)*k,t[14]=(f*x-g*w-m*v)*k,t[15]=(_*w-l*x+u*v)*k,t):null}},function(t,i){"use strict";function e(t,i){this._context=t,this._splitter=this._context.createChannelSplitter(4),this._merger=this._context.createChannelMerger(4),this._channelMap=i||n,this._splitter.connect(this._merger,0,this._channelMap[0]),this._splitter.connect(this._merger,1,this._channelMap[1]),this._splitter.connect(this._merger,2,this._channelMap[2]),this._splitter.connect(this._merger,3,this._channelMap[3]),this.input=this._splitter,this.output=this._merger}var n=[0,1,2,3];e.prototype.setChannelMap=function(t){t&&(this._channelMap=t,this._splitter.disconnect(),this._splitter.connect(this._merger,0,this._channelMap[0]),this._splitter.connect(this._merger,1,this._channelMap[1]),this._splitter.connect(this._merger,2,this._channelMap[2]),this._splitter.connect(this._merger,3,this._channelMap[3]))},t.exports=e},function(t,i){"use strict";function e(t){this._context=t,this._splitter=this._context.createChannelSplitter(4),this._inY=this._context.createGain(),this._inZ=this._context.createGain(),this._inX=this._context.createGain(),this._m0=this._context.createGain(),this._m1=this._context.createGain(),this._m2=this._context.createGain(),this._m3=this._context.createGain(),this._m4=this._context.createGain(),this._m5=this._context.createGain(),this._m6=this._context.createGain(),this._m7=this._context.createGain(),this._m8=this._context.createGain(),this._outY=this._context.createGain(),this._outZ=this._context.createGain(),this._outX=this._context.createGain(),this._merger=this._context.createChannelMerger(4),this._splitter.connect(this._inY,1),this._splitter.connect(this._inZ,2),this._splitter.connect(this._inX,3),this._inY.gain.value=-1,this._inX.gain.value=-1,this._inY.connect(this._m0),this._inY.connect(this._m1),this._inY.connect(this._m2),this._inZ.connect(this._m3),this._inZ.connect(this._m4),this._inZ.connect(this._m5),this._inX.connect(this._m6),this._inX.connect(this._m7),this._inX.connect(this._m8),this._m0.connect(this._outY),this._m1.connect(this._outZ),this._m2.connect(this._outX),this._m3.connect(this._outY),this._m4.connect(this._outZ),this._m5.connect(this._outX),this._m6.connect(this._outY),this._m7.connect(this._outZ),this._m8.connect(this._outX),this._splitter.connect(this._merger,0,0),this._outY.connect(this._merger,0,1),this._outZ.connect(this._merger,0,2),this._outX.connect(this._merger,0,3),this._outY.gain.value=-1,this._outX.gain.value=-1,this.setRotationMatrix(new Float32Array([1,0,0,0,1,0,0,0,1])),this.input=this._splitter,this.output=this._merger}e.prototype.setRotationMatrix=function(t){this._m0.gain.value=t[0],this._m1.gain.value=t[1],this._m2.gain.value=t[2],this._m3.gain.value=t[3],this._m4.gain.value=t[4],this._m5.gain.value=t[5],this._m6.gain.value=t[6],this._m7.gain.value=t[7],this._m8.gain.value=t[8]},e.prototype.setRotationMatrix4=function(t){this._m0.gain.value=t[0],this._m1.gain.value=t[1],this._m2.gain.value=t[2],this._m3.gain.value=t[4],this._m4.gain.value=t[5],this._m5.gain.value=t[6],this._m6.gain.value=t[8],this._m7.gain.value=t[9],this._m8.gain.value=t[10]},e.prototype.getRotationMatrix=function(){return[this._m0.gain.value,this._m1.gain.value,this._m2.gain.value,this._m3.gain.value,this._m4.gain.value,this._m5.gain.value,this._m6.gain.value,this._m7.gain.value,this._m8.gain.value]},t.exports=e},function(t,i,e){"use strict";function n(t,i){var e=Math.tan(Math.PI*t/i),n=e*e,s=n+2*e+1;return{lowpassA:[1,2*(n-1)/s,(n-2*e+1)/s],lowpassB:[n/s,2*n/s,n/s],hipassA:[1,2*(n-1)/s,(n-2*e+1)/s],hipassB:[1/s,-2/s,1/s]}}function s(t){if(this._context=t,this._input=this._context.createGain(),this._context.createIIRFilter){var i=n(a,this._context.sampleRate);this._lpf=this._context.createIIRFilter(i.lowpassB,i.lowpassA),this._hpf=this._context.createIIRFilter(i.hipassB,i.hipassA)}else o.log("IIR filter is missing. Using Biquad filter instead."),this._lpf=this._context.createBiquadFilter(),this._hpf=this._context.createBiquadFilter(),this._lpf.frequency.value=a,this._hpf.frequency.value=a,this._hpf.type="highpass";this._splitterLow=this._context.createChannelSplitter(4),this._splitterHigh=this._context.createChannelSplitter(4),this._gainHighW=this._context.createGain(),this._gainHighY=this._context.createGain(),this._gainHighZ=this._context.createGain(),this._gainHighX=this._context.createGain(),this._merger=this._context.createChannelMerger(4),this._input.connect(this._hpf),this._hpf.connect(this._splitterHigh),this._splitterHigh.connect(this._gainHighW,0),this._splitterHigh.connect(this._gainHighY,1),this._splitterHigh.connect(this._gainHighZ,2),this._splitterHigh.connect(this._gainHighX,3),this._gainHighW.connect(this._merger,0,0),this._gainHighY.connect(this._merger,0,1),this._gainHighZ.connect(this._merger,0,2),this._gainHighX.connect(this._merger,0,3),this._input.connect(this._lpf),this._lpf.connect(this._splitterLow),this._splitterLow.connect(this._merger,0,0),this._splitterLow.connect(this._merger,1,1),this._splitterLow.connect(this._merger,2,2),this._splitterLow.connect(this._merger,3,3);var e=this._context.currentTime;this._gainHighW.gain.setValueAtTime(-1*h[0],e),this._gainHighY.gain.setValueAtTime(-1*h[1],e),this._gainHighZ.gain.setValueAtTime(-1*h[2],e),this._gainHighX.gain.setValueAtTime(-1*h[3],e),this.input=this._input,this.output=this._merger}var o=e(3),a=690,h=[1.4142,.8166,.8166,.8166];t.exports=s},function(t,i){"use strict";function e(t,i){if(2!==i.IR.numberOfChannels)throw"IR does not have 2 channels. cannot proceed.";this._active=!1,this._context=t,this._input=this._context.createChannelSplitter(4),this._cW=this._context.createGain(),this._cY=this._context.createGain(),this._cZ=this._context.createGain(),this._cX=this._context.createGain(),this._convolver=this._context.createConvolver(),this._gain=this._context.createGain(),this._input.connect(this._cW,0),this._input.connect(this._cY,1),this._input.connect(this._cZ,2),this._input.connect(this._cX,3),this._cW.connect(this._convolver),this._cY.connect(this._convolver),this._cZ.connect(this._convolver),this._cX.connect(this._convolver),this._convolver.connect(this._gain),this._gain.connect(this._context.destination),this.enable(),this._convolver.normalize=!1,this._convolver.buffer=i.IR,this._gain.gain.value=i.gain,this._cW.gain.value=i.coefficients[0],this._cY.gain.value=i.coefficients[1],this._cZ.gain.value=i.coefficients[2],this._cX.gain.value=i.coefficients[3],this.input=this._input}e.prototype.enable=function(){this._gain.connect(this._context.destination),this._active=!0},e.prototype.disable=function(){this._gain.disconnect(),this._active=!1},t.exports=e},function(t,i,e){"use strict";function n(t,i,e){this._isDecoderReady=!1,this._context=t,this._videoElement=i,this._decodingMode="ambisonic",this._postGainDB=p,this._HRTFSetUrl=u,this._channelMap=g,e&&(e.postGainDB&&(this._postGainDB=e.postGainDB),e.HRTFSetUrl&&(this._HRTFSetUrl=e.HRTFSetUrl),e.channelMap&&(this._channelMap=e.channelMap)),this._speakerData=[];for(var n=0;n<r.length;++n)this._speakerData.push({name:r[n].name,url:this._HRTFSetUrl+"/"+r[n].url,coef:r[n].coef});this._tempMatrix4=new Float32Array(16)}var s=e(2),o=e(4),a=e(5),h=e(6),c=e(7),r=e(9),_=e(3),l=e(10),u="https://raw.githubusercontent.com/google/spatial-media/master/support/hrtfs/cube/",p=0,g=[0,1,2,3];n.prototype.initialize=function(){_.log("Version: "+l),_.log("Initializing... (mode: "+this._decodingMode+")");var t=this._channelMap.toString();t!==g.toString()&&_.log("Remapping channels ([0,1,2,3] -> ["+t+"])"),this._audioElementSource=this._context.createMediaElementSource(this._videoElement),this._foaRouter=new o(this._context,this._channelMap),this._foaRotator=new a(this._context),this._foaPhaseMatchedFilter=new h(this._context),this._audioElementSource.connect(this._foaRouter.input),this._foaRouter.output.connect(this._foaRotator.input),this._foaRotator.output.connect(this._foaPhaseMatchedFilter.input),this._foaVirtualSpeakers=[],this._bypass=this._context.createGain(),this._audioElementSource.connect(this._bypass);var i=Math.pow(10,this._postGainDB/20);_.log("Gain compensation: "+i+" ("+this._postGainDB+"dB)");var e=this;return new Promise(function(t,n){new s(e._context,e._speakerData,function(n){for(var s=0;s<e._speakerData.length;++s)e._foaVirtualSpeakers[s]=new c(e._context,{coefficients:e._speakerData[s].coef,IR:n.get(e._speakerData[s].name),gain:i}),e._foaPhaseMatchedFilter.output.connect(e._foaVirtualSpeakers[s].input);e.setMode(e._decodingMode),e._isDecoderReady=!0,_.log("HRTF IRs are loaded successfully. The decoder is ready."),t()},n)})},n.prototype.setRotationMatrix=function(t){this._foaRotator.setRotationMatrix(t)},n.prototype.setRotationMatrixFromCamera=function(t){_.invertMatrix4(this._tempMatrix4,t.elements),this._foaRotator.setRotationMatrix4(this._tempMatrix4)},n.prototype.setMode=function(t){if(t!==this._decodingMode){switch(t){case"bypass":this._decodingMode="bypass";for(var i=0;i<this._foaVirtualSpeakers.length;++i)this._foaVirtualSpeakers[i].disable();this._bypass.connect(this._context.destination);break;case"ambisonic":this._decodingMode="ambisonic";for(var i=0;i<this._foaVirtualSpeakers.length;++i)this._foaVirtualSpeakers[i].enable();this._bypass.disconnect();break;case"off":this._decodingMode="off";for(var i=0;i<this._foaVirtualSpeakers.length;++i)this._foaVirtualSpeakers[i].disable();this._bypass.disconnect()}_.log("Decoding mode changed. ("+t+")")}},t.exports=n},function(t,i){var e=[{name:"E35.26_A135",url:"E35.26_A135_D1.4.wav",gainFactor:1,coef:[.125,.216495,.21653,-.216495]},{name:"E35.26_A-135",url:"E35.26_A-135_D1.4.wav",gainFactor:1,coef:[.125,-.216495,.21653,-.216495]},{name:"E-35.26_A135",url:"E-35.26_A135_D1.4.wav",gainFactor:1,coef:[.125,.216495,-.21653,-.216495]},{name:"E-35.26_A-135",url:"E-35.26_A-135_D1.4.wav",gainFactor:1,coef:[.125,-.216495,-.21653,-.216495]},{name:"E35.26_A45",url:"E35.26_A45_D1.4.wav",gainFactor:1,coef:[.125,.216495,.21653,.216495]},{name:"E35.26_A-45",url:"E35.26_A-45_D1.4.wav",gainFactor:1,coef:[.125,-.216495,.21653,.216495]},{name:"E-35.26_A45",url:"E-35.26_A45_D1.4.wav",gainFactor:1,coef:[.125,.216495,-.21653,.216495]},{name:"E-35.26_A-45",url:"E-35.26_A-45_D1.4.wav",gainFactor:1,coef:[.125,-.216495,-.21653,.216495]}];t.exports=e},function(t,i){"use strict";t.exports="0.1.7"}])});
\ No newline at end of file
+"use strict";i.Omnitone=e(1)},function(t,i,e){"use strict";var n={},s=e(2),o=e(4),a=e(5),h=e(6),c=e(7),r=e(8);n.loadAudioBuffers=function(t,i){return new Promise(function(e,n){new s(t,i,function(t){e(t)},n)})},n.createFOARouter=function(t,i){return new o(t,i)},n.createFOARotator=function(t){return new a(t)},n.createFOAPhaseMatchedFilter=function(t){return new h(t)},n.createFOAVirtualSpeaker=function(t,i){return new c(t,i)},n.createFOADecoder=function(t,i,e){return new r(t,i,e)},t.exports=n},function(t,i,e){"use strict";function n(t,i,e,n,o){this._context=t,this._buffers=new Map,this._loadingTasks={},this._resolve=e,this._reject=n,this._progress=o;for(var a=0;a<i.length;a++){var h=i[a];if(this._loadingTasks.hasOwnProperty(h.name))return void s.log("Duplicated filename when loading: "+h.name);this._loadingTasks[h.name]=0,this._loadAudioFile(h)}}var s=e(3);n.prototype._loadAudioFile=function(t){var i=new XMLHttpRequest;i.open("GET",t.url),i.responseType="arraybuffer";var e=this;i.onload=function(){200===i.status?e._context.decodeAudioData(i.response,function(i){e._done(t.name,i)},function(i){s.log("Decoding failure: "+t.url+" ("+i+")"),e._done(t.name,null)}):(s.log("XHR Error: "+t.url+" ("+i.statusText+")"),e._done(t.name,null))},i.onerror=function(i){s.log("XHR Network failure: "+t.url),e._done(t.name,null)},i.send()},n.prototype._done=function(t,i){this._loadingTasks[t]=null!==i?"loaded":"failed",this._buffers.set(t,i),this._updateProgress(t)},n.prototype._updateProgress=function(t){var i=0,e=0,n=0;for(var s in this._loadingTasks)n++,"loaded"===this._loadingTasks[s]?i++:"failed"===this._loadingTasks[s]&&e++;"function"==typeof this._progress&&this._progress(t,i,n),i===n&&this._resolve(this._buffers),i+e===n&&this._reject(this._buffers)},t.exports=n},function(t,i){"use strict";i.log=function(){window.console.log.apply(window.console,["%c[Omnitone]%c "+Array.prototype.slice.call(arguments).join(" ")+" %c(@"+performance.now().toFixed(2)+"ms)","background: #BBDEFB; color: #FF5722; font-weight: 700","font-weight: 400","color: #AAA"])},i.invertMatrix4=function(t,i){var e=i[0],n=i[1],s=i[2],o=i[3],a=i[4],h=i[5],c=i[6],r=i[7],_=i[8],l=i[9],u=i[10],p=i[11],g=i[12],f=i[13],m=i[14],d=i[15],v=e*h-n*a,x=e*c-s*a,M=e*r-o*a,w=n*c-s*h,y=n*r-o*h,R=s*r-o*c,A=_*f-l*g,F=_*m-u*g,G=_*d-p*g,b=l*m-u*f,H=l*d-p*f,D=u*d-p*m,k=v*D-x*H+M*b+w*G-y*F+R*A;return k?(k=1/k,t[0]=(h*D-c*H+r*b)*k,t[1]=(s*H-n*D-o*b)*k,t[2]=(f*R-m*y+d*w)*k,t[3]=(u*y-l*R-p*w)*k,t[4]=(c*G-a*D-r*F)*k,t[5]=(e*D-s*G+o*F)*k,t[6]=(m*M-g*R-d*x)*k,t[7]=(_*R-u*M+p*x)*k,t[8]=(a*H-h*G+r*A)*k,t[9]=(n*G-e*H-o*A)*k,t[10]=(g*y-f*M+d*v)*k,t[11]=(l*M-_*y-p*v)*k,t[12]=(h*F-a*b-c*A)*k,t[13]=(e*b-n*F+s*A)*k,t[14]=(f*x-g*w-m*v)*k,t[15]=(_*w-l*x+u*v)*k,t):null}},function(t,i){"use strict";function e(t,i){this._context=t,this._splitter=this._context.createChannelSplitter(4),this._merger=this._context.createChannelMerger(4),this._channelMap=i||n,this._splitter.connect(this._merger,0,this._channelMap[0]),this._splitter.connect(this._merger,1,this._channelMap[1]),this._splitter.connect(this._merger,2,this._channelMap[2]),this._splitter.connect(this._merger,3,this._channelMap[3]),this.input=this._splitter,this.output=this._merger}var n=[0,1,2,3];e.prototype.setChannelMap=function(t){t&&(this._channelMap=t,this._splitter.disconnect(),this._splitter.connect(this._merger,0,this._channelMap[0]),this._splitter.connect(this._merger,1,this._channelMap[1]),this._splitter.connect(this._merger,2,this._channelMap[2]),this._splitter.connect(this._merger,3,this._channelMap[3]))},t.exports=e},function(t,i){"use strict";function e(t){this._context=t,this._splitter=this._context.createChannelSplitter(4),this._inY=this._context.createGain(),this._inZ=this._context.createGain(),this._inX=this._context.createGain(),this._m0=this._context.createGain(),this._m1=this._context.createGain(),this._m2=this._context.createGain(),this._m3=this._context.createGain(),this._m4=this._context.createGain(),this._m5=this._context.createGain(),this._m6=this._context.createGain(),this._m7=this._context.createGain(),this._m8=this._context.createGain(),this._outY=this._context.createGain(),this._outZ=this._context.createGain(),this._outX=this._context.createGain(),this._merger=this._context.createChannelMerger(4),this._splitter.connect(this._inY,1),this._splitter.connect(this._inZ,2),this._splitter.connect(this._inX,3),this._inY.gain.value=-1,this._inX.gain.value=-1,this._inY.connect(this._m0),this._inY.connect(this._m1),this._inY.connect(this._m2),this._inZ.connect(this._m3),this._inZ.connect(this._m4),this._inZ.connect(this._m5),this._inX.connect(this._m6),this._inX.connect(this._m7),this._inX.connect(this._m8),this._m0.connect(this._outY),this._m1.connect(this._outZ),this._m2.connect(this._outX),this._m3.connect(this._outY),this._m4.connect(this._outZ),this._m5.connect(this._outX),this._m6.connect(this._outY),this._m7.connect(this._outZ),this._m8.connect(this._outX),this._splitter.connect(this._merger,0,0),this._outY.connect(this._merger,0,1),this._outZ.connect(this._merger,0,2),this._outX.connect(this._merger,0,3),this._outY.gain.value=-1,this._outX.gain.value=-1,this.setRotationMatrix(new Float32Array([1,0,0,0,1,0,0,0,1])),this.input=this._splitter,this.output=this._merger}e.prototype.setRotationMatrix=function(t){this._m0.gain.value=t[0],this._m1.gain.value=t[1],this._m2.gain.value=t[2],this._m3.gain.value=t[3],this._m4.gain.value=t[4],this._m5.gain.value=t[5],this._m6.gain.value=t[6],this._m7.gain.value=t[7],this._m8.gain.value=t[8]},e.prototype.setRotationMatrix4=function(t){this._m0.gain.value=t[0],this._m1.gain.value=t[1],this._m2.gain.value=t[2],this._m3.gain.value=t[4],this._m4.gain.value=t[5],this._m5.gain.value=t[6],this._m6.gain.value=t[8],this._m7.gain.value=t[9],this._m8.gain.value=t[10]},e.prototype.getRotationMatrix=function(){return[this._m0.gain.value,this._m1.gain.value,this._m2.gain.value,this._m3.gain.value,this._m4.gain.value,this._m5.gain.value,this._m6.gain.value,this._m7.gain.value,this._m8.gain.value]},t.exports=e},function(t,i,e){"use strict";function n(t,i){var e=Math.tan(Math.PI*t/i),n=e*e,s=n+2*e+1;return{lowpassA:[1,2*(n-1)/s,(n-2*e+1)/s],lowpassB:[n/s,2*n/s,n/s],hipassA:[1,2*(n-1)/s,(n-2*e+1)/s],hipassB:[1/s,-2/s,1/s]}}function s(t){if(this._context=t,this._input=this._context.createGain(),this._context.createIIRFilter){var i=n(a,this._context.sampleRate);this._lpf=this._context.createIIRFilter(i.lowpassB,i.lowpassA),this._hpf=this._context.createIIRFilter(i.hipassB,i.hipassA)}else o.log("IIR filter is missing. Using Biquad filter instead."),this._lpf=this._context.createBiquadFilter(),this._hpf=this._context.createBiquadFilter(),this._lpf.frequency.value=a,this._hpf.frequency.value=a,this._hpf.type="highpass";this._splitterLow=this._context.createChannelSplitter(4),this._splitterHigh=this._context.createChannelSplitter(4),this._gainHighW=this._context.createGain(),this._gainHighY=this._context.createGain(),this._gainHighZ=this._context.createGain(),this._gainHighX=this._context.createGain(),this._merger=this._context.createChannelMerger(4),this._input.connect(this._hpf),this._hpf.connect(this._splitterHigh),this._splitterHigh.connect(this._gainHighW,0),this._splitterHigh.connect(this._gainHighY,1),this._splitterHigh.connect(this._gainHighZ,2),this._splitterHigh.connect(this._gainHighX,3),this._gainHighW.connect(this._merger,0,0),this._gainHighY.connect(this._merger,0,1),this._gainHighZ.connect(this._merger,0,2),this._gainHighX.connect(this._merger,0,3),this._input.connect(this._lpf),this._lpf.connect(this._splitterLow),this._splitterLow.connect(this._merger,0,0),this._splitterLow.connect(this._merger,1,1),this._splitterLow.connect(this._merger,2,2),this._splitterLow.connect(this._merger,3,3);var e=this._context.currentTime;this._gainHighW.gain.setValueAtTime(-1*h[0],e),this._gainHighY.gain.setValueAtTime(-1*h[1],e),this._gainHighZ.gain.setValueAtTime(-1*h[2],e),this._gainHighX.gain.setValueAtTime(-1*h[3],e),this.input=this._input,this.output=this._merger}var o=e(3),a=690,h=[1.4142,.8166,.8166,.8166];t.exports=s},function(t,i){"use strict";function e(t,i){if(2!==i.IR.numberOfChannels)throw"IR does not have 2 channels. cannot proceed.";this._active=!1,this._context=t,this._input=this._context.createChannelSplitter(4),this._cW=this._context.createGain(),this._cY=this._context.createGain(),this._cZ=this._context.createGain(),this._cX=this._context.createGain(),this._convolver=this._context.createConvolver(),this._gain=this._context.createGain(),this._input.connect(this._cW,0),this._input.connect(this._cY,1),this._input.connect(this._cZ,2),this._input.connect(this._cX,3),this._cW.connect(this._convolver),this._cY.connect(this._convolver),this._cZ.connect(this._convolver),this._cX.connect(this._convolver),this._convolver.connect(this._gain),this._gain.connect(this._context.destination),this.enable(),this._convolver.normalize=!1,this._convolver.buffer=i.IR,this._gain.gain.value=i.gain,this._cW.gain.value=i.coefficients[0],this._cY.gain.value=i.coefficients[1],this._cZ.gain.value=i.coefficients[2],this._cX.gain.value=i.coefficients[3],this.input=this._input}e.prototype.enable=function(){this._gain.connect(this._context.destination),this._active=!0},e.prototype.disable=function(){this._gain.disconnect(),this._active=!1},t.exports=e},function(t,i,e){"use strict";function n(t,i,e){this._isDecoderReady=!1,this._context=t,this._videoElement=i,this._decodingMode="ambisonic",this._postGainDB=p,this._HRTFSetUrl=u,this._channelMap=g,e&&(e.postGainDB&&(this._postGainDB=e.postGainDB),e.HRTFSetUrl&&(this._HRTFSetUrl=e.HRTFSetUrl),e.channelMap&&(this._channelMap=e.channelMap)),this._speakerData=[];for(var n=0;n<r.length;++n)this._speakerData.push({name:r[n].name,url:this._HRTFSetUrl+"/"+r[n].url,coef:r[n].coef});this._tempMatrix4=new Float32Array(16)}var s=e(2),o=e(4),a=e(5),h=e(6),c=e(7),r=e(9),_=e(3),l=e(10),u="https://raw.githubusercontent.com/google/spatial-media/master/support/hrtfs/cube/",p=0,g=[0,1,2,3];n.prototype.initialize=function(){_.log("Version: "+l),_.log("Initializing... (mode: "+this._decodingMode+")");var t=this._channelMap.toString();t!==g.toString()&&_.log("Remapping channels ([0,1,2,3] -> ["+t+"])"),this._audioElementSource=this._context.createMediaElementSource(this._videoElement),this._foaRouter=new o(this._context,this._channelMap),this._foaRotator=new a(this._context),this._foaPhaseMatchedFilter=new h(this._context),this._audioElementSource.connect(this._foaRouter.input),this._foaRouter.output.connect(this._foaRotator.input),this._foaRotator.output.connect(this._foaPhaseMatchedFilter.input),this._foaVirtualSpeakers=[],this._bypass=this._context.createGain(),this._audioElementSource.connect(this._bypass);var i=Math.pow(10,this._postGainDB/20);_.log("Gain compensation: "+i+" ("+this._postGainDB+"dB)");var e=this;return new Promise(function(t,n){new s(e._context,e._speakerData,function(n){for(var s=0;s<e._speakerData.length;++s)e._foaVirtualSpeakers[s]=new c(e._context,{coefficients:e._speakerData[s].coef,IR:n.get(e._speakerData[s].name),gain:i}),e._foaPhaseMatchedFilter.output.connect(e._foaVirtualSpeakers[s].input);e.setMode(e._decodingMode),e._isDecoderReady=!0,_.log("HRTF IRs are loaded successfully. The decoder is ready."),t()},n)})},n.prototype.setRotationMatrix=function(t){this._foaRotator.setRotationMatrix(t)},n.prototype.setRotationMatrixFromCamera=function(t){_.invertMatrix4(this._tempMatrix4,t.elements),this._foaRotator.setRotationMatrix4(this._tempMatrix4)},n.prototype.setMode=function(t){if(t!==this._decodingMode){switch(t){case"bypass":this._decodingMode="bypass";for(var i=0;i<this._foaVirtualSpeakers.length;++i)this._foaVirtualSpeakers[i].disable();this._bypass.connect(this._context.destination);break;case"ambisonic":this._decodingMode="ambisonic";for(var i=0;i<this._foaVirtualSpeakers.length;++i)this._foaVirtualSpeakers[i].enable();this._bypass.disconnect();break;case"off":this._decodingMode="off";for(var i=0;i<this._foaVirtualSpeakers.length;++i)this._foaVirtualSpeakers[i].disable();this._bypass.disconnect()}_.log("Decoding mode changed. ("+t+")")}},t.exports=n},function(t,i){var e=[{name:"E35.26_A135",url:"E35.26_A135_D1.4.wav",gainFactor:1,coef:[.125,.216495,.21653,-.216495]},{name:"E35.26_A-135",url:"E35.26_A-135_D1.4.wav",gainFactor:1,coef:[.125,-.216495,.21653,-.216495]},{name:"E-35.26_A135",url:"E-35.26_A135_D1.4.wav",gainFactor:1,coef:[.125,.216495,-.21653,-.216495]},{name:"E-35.26_A-135",url:"E-35.26_A-135_D1.4.wav",gainFactor:1,coef:[.125,-.216495,-.21653,-.216495]},{name:"E35.26_A45",url:"E35.26_A45_D1.4.wav",gainFactor:1,coef:[.125,.216495,.21653,.216495]},{name:"E35.26_A-45",url:"E35.26_A-45_D1.4.wav",gainFactor:1,coef:[.125,-.216495,.21653,.216495]},{name:"E-35.26_A45",url:"E-35.26_A45_D1.4.wav",gainFactor:1,coef:[.125,.216495,-.21653,.216495]},{name:"E-35.26_A-45",url:"E-35.26_A-45_D1.4.wav",gainFactor:1,coef:[.125,-.216495,-.21653,.216495]}];t.exports=e},function(t,i){"use strict";t.exports="0.1.8"}])});
\ No newline at end of file

From 62dab229b086107709eb95ab447fdde10c2fb815 Mon Sep 17 00:00:00 2001
From: Hongchan Choi <hongchan@chromium.org>
Date: Mon, 7 Nov 2016 13:31:48 -0800
Subject: [PATCH 4/4] remove unnecessary comments

---
 src/foa-phase-matched-filter.js | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/src/foa-phase-matched-filter.js b/src/foa-phase-matched-filter.js
index 69d60c0..6d85f5c 100644
--- a/src/foa-phase-matched-filter.js
+++ b/src/foa-phase-matched-filter.js
@@ -96,10 +96,6 @@ function FOAPhaseMatchedFilter (context) {
   // Apply gain correction to hi-passed pressure and velocity components:
   // Inverting sign is necessary as the low-passed and high-passed portion are
   // out-of-phase after the filtering.
-  // this._gainHighW.gain.value = -1 * GAIN_COEFFICIENTS[0];
-  // this._gainHighY.gain.value = -1 * GAIN_COEFFICIENTS[1];
-  // this._gainHighZ.gain.value = -1 * GAIN_COEFFICIENTS[2];
-  // this._gainHighX.gain.value = -1 * GAIN_COEFFICIENTS[3];
   var now = this._context.currentTime;
   this._gainHighW.gain.setValueAtTime(-1 * GAIN_COEFFICIENTS[0], now);
   this._gainHighY.gain.setValueAtTime(-1 * GAIN_COEFFICIENTS[1], now);