Implement Automations for PannerNode and AutioListener

third_party/WebKit/Source/platform/audio/EqualPowerPanner.cpp

Index: third_party/WebKit/Source/platform/audio/EqualPowerPanner.cpp
diff --git a/third_party/WebKit/Source/platform/audio/EqualPowerPanner.cpp b/third_party/WebKit/Source/platform/audio/EqualPowerPanner.cpp
index 968fee73e2724d4495130a4a032937d314cfbb11..2a17a0ff6caac1c5b30d2084286eeb5cfe122dd3 100644
--- a/third_party/WebKit/Source/platform/audio/EqualPowerPanner.cpp
+++ b/third_party/WebKit/Source/platform/audio/EqualPowerPanner.cpp
@@ -29,18 +29,11 @@
 #include <algorithm>
 #include <cmath>
 
-// Use a 50ms smoothing / de-zippering time-constant.
-const float SmoothingTimeConstant = 0.050f;
-
 namespace blink {
 
 EqualPowerPanner::EqualPowerPanner(float sampleRate)
     : Panner(PanningModelEqualPower)
-    , m_isFirstRender(true)
-    , m_gainL(0.0)
-    , m_gainR(0.0)
 {
-    m_smoothingConstant = AudioUtilities::discreteTimeConstantForSampleRate(SmoothingTimeConstant, sampleRate);
 }
 
 void EqualPowerPanner::pan(double azimuth, double /*elevation*/, const AudioBus* inputBus, AudioBus* outputBus, size_t framesToProcess)
@@ -97,54 +90,122 @@ void EqualPowerPanner::pan(double azimuth, double /*elevation*/, const AudioBus*
     desiredGainL = std::cos(piOverTwoDouble * desiredPanPosition);
     desiredGainR = std::sin(piOverTwoDouble * desiredPanPosition);
 
-    // Don't de-zipper on first render call.
-    if (m_isFirstRender) {
-        m_isFirstRender = false;
-        m_gainL = desiredGainL;
-        m_gainR = desiredGainR;
-    }
-
-    // Cache in local variables.
-    double gainL = m_gainL;
-    double gainR = m_gainR;
-
-    // Get local copy of smoothing constant.
-    const double SmoothingConstant = m_smoothingConstant;
-
     int n = framesToProcess;
 
     if (numberOfInputChannels == 1) { // For mono source case.
         while (n--) {
             float inputL = *sourceL++;
-            gainL += (desiredGainL - gainL) * SmoothingConstant;
-            gainR += (desiredGainR - gainR) * SmoothingConstant;
-            *destinationL++ = static_cast<float>(inputL * gainL);
-            *destinationR++ = static_cast<float>(inputL * gainR);
+
+            *destinationL++ = static_cast<float>(inputL * desiredGainL);
+            *destinationR++ = static_cast<float>(inputL * desiredGainR);
         }
     } else { // For stereo source case.
         if (azimuth <= 0) { // from -90 -> 0
             while (n--) {
                 float inputL = *sourceL++;
                 float inputR = *sourceR++;
-                gainL += (desiredGainL - gainL) * SmoothingConstant;
-                gainR += (desiredGainR - gainR) * SmoothingConstant;
-                *destinationL++ = static_cast<float>(inputL + inputR * gainL);
-                *destinationR++ = static_cast<float>(inputR * gainR);
+
+                *destinationL++ = static_cast<float>(inputL + inputR * desiredGainL);
+                *destinationR++ = static_cast<float>(inputR * desiredGainR);
             }
         } else { // from 0 -> +90
             while (n--) {
                 float inputL = *sourceL++;
                 float inputR = *sourceR++;
-                gainL += (desiredGainL - gainL) * SmoothingConstant;
-                gainR += (desiredGainR - gainR) * SmoothingConstant;
-                *destinationL++ = static_cast<float>(inputL * gainL);
-                *destinationR++ = static_cast<float>(inputR + inputL * gainR);
+
+                *destinationL++ = static_cast<float>(inputL * desiredGainL);
+                *destinationR++ = static_cast<float>(inputR + inputL * desiredGainR);
             }
         }
     }
+}
+
+void EqualPowerPanner::calculateDesiredGain(double& desiredGainL, double& desiredGainR, double azimuth, int numberOfInputChannels)
+{
+    // Clamp azimuth to allowed range of -180 -> +180.
+    azimuth = clampTo(azimuth, -180.0, 180.0);
+
+    // Alias the azimuth ranges behind us to in front of us:
+    // -90 -> -180 to -90 -> 0 and 90 -> 180 to 90 -> 0
+    if (azimuth < -90)
+        azimuth = -180 - azimuth;
+    else if (azimuth > 90)
+        azimuth = 180 - azimuth;
+
+    double desiredPanPosition;
+
+    if (numberOfInputChannels == 1) { // For mono source case.
+        // Pan smoothly from left to right with azimuth going from -90 -> +90 degrees.
+        desiredPanPosition = (azimuth + 90) / 180;
+    } else { // For stereo source case.
+        if (azimuth <= 0) { // from -90 -> 0
+            // sourceL -> destL and "equal-power pan" sourceR as in mono case
+            // by transforming the "azimuth" value from -90 -> 0 degrees into the range -90 -> +90.
+            desiredPanPosition = (azimuth + 90) / 90;
+        } else { // from 0 -> +90
+            // sourceR -> destR and "equal-power pan" sourceL as in mono case
+            // by transforming the "azimuth" value from 0 -> +90 degrees into the range -90 -> +90.
+            desiredPanPosition = azimuth / 90;
+        }
+    }
 
-    m_gainL = gainL;
-    m_gainR = gainR;
+    desiredGainL = std::cos(piOverTwoDouble * desiredPanPosition);
+    desiredGainR = std::sin(piOverTwoDouble * desiredPanPosition);
+}
+
+void EqualPowerPanner::panWithSampleAccurateValues(double* azimuth, double* /*elevation*/, const AudioBus* inputBus, AudioBus* outputBus, size_t framesToProcess)
+{
+    bool isInputSafe = inputBus && (inputBus->numberOfChannels() == 1 || inputBus->numberOfChannels() == 2) && framesToProcess <= inputBus->length();
+    DCHECK(isInputSafe);
+    if (!isInputSafe)
+        return;
+
+    unsigned numberOfInputChannels = inputBus->numberOfChannels();
+
+    bool isOutputSafe = outputBus && outputBus->numberOfChannels() == 2 && framesToProcess <= outputBus->length();
+    DCHECK(isOutputSafe);
+    if (!isOutputSafe)
+        return;
+
+    const float* sourceL = inputBus->channel(0)->data();
+    const float* sourceR = numberOfInputChannels > 1 ? inputBus->channel(1)->data() : sourceL;
+    float* destinationL = outputBus->channelByType(AudioBus::ChannelLeft)->mutableData();
+    float* destinationR = outputBus->channelByType(AudioBus::ChannelRight)->mutableData();
+
+    if (!sourceL || !sourceR || !destinationL || !destinationR)
+        return;
+
+    int n = framesToProcess;
+
+    if (numberOfInputChannels == 1) { // For mono source case.
+        for (int k = 0; k < n; ++k) {
+            double desiredGainL;
+            double desiredGainR;
+            float inputL = *sourceL++;
+
+            calculateDesiredGain(desiredGainL, desiredGainR, azimuth[k], numberOfInputChannels);
+            *destinationL++ = static_cast<float>(inputL * desiredGainL);
+            *destinationR++ = static_cast<float>(inputL * desiredGainR);
+        }
+    } else { // For stereo source case.
+        for (int k = 0; k < n; ++k) {
+            double desiredGainL;
+            double desiredGainR;
+
+            calculateDesiredGain(desiredGainL, desiredGainR, azimuth[k], numberOfInputChannels);
+            if (azimuth[k] <= 0) { // from -90 -> 0
+                float inputL = *sourceL++;
+                float inputR = *sourceR++;
+                *destinationL++ = static_cast<float>(inputL + inputR * desiredGainL);
+                *destinationR++ = static_cast<float>(inputR * desiredGainR);
+            } else { // from 0 -> +90
+                float inputL = *sourceL++;
+                float inputR = *sourceR++;
+                *destinationL++ = static_cast<float>(inputL * desiredGainL);
+                *destinationR++ = static_cast<float>(inputR + inputL * desiredGainR);
+            }
+        }
+    }
 }
 
 } // namespace blink