Implement Automations for PannerNode and AutioListener

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

 /*
  * Copyright (C) 2010, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
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             } else if (m_crossfadeIncr < 0 && fabs(m_crossfadeX) < -m_crossfadeIncr) {
                 // We've fully made the crossfade transition from 2 -> 1.
                 m_crossfadeSelection = CrossfadeSelection1;
                 m_crossfadeX = 0;
                 m_crossfadeIncr = 0;
             }
         }
     }
 }
 
+void HRTFPanner::panWithSampleAccurateValues(double* desiredAzimuth, double* elevation, const AudioBus* inputBus, AudioBus* outputBus, size_t framesToProcess)
+{
+    // Sample-accurate (a-rate) HRTF panner is not implemented, just k-rate.  Just grab the current
+    // azimuth/elevation and use that.
+    //
+    // We are assuming that the inherent smoothing in the HRTF processing is good enough, and we
+    // don't want to increase the complexity of the HRTF panner by 15-20 times.  (We need to cmopute
+    // one output sample for each possibly different impulse response.  That N^2.  Previously, we
+    // used an FFT to do them all at once for a complexity of N/log2(N).  Hence, N/log2(N) times
+    // more complex.)
+    pan(desiredAzimuth[0], elevation[0], inputBus, outputBus, framesToProcess);
+}
+
 double HRTFPanner::tailTime() const
 {
     // Because HRTFPanner is implemented with a DelayKernel and a FFTConvolver, the tailTime of the HRTFPanner
     // is the sum of the tailTime of the DelayKernel and the tailTime of the FFTConvolver, which is MaxDelayTimeSeconds
     // and fftSize() / 2, respectively.
     return MaxDelayTimeSeconds + (fftSize() / 2) / static_cast<double>(sampleRate());
 }
 
 double HRTFPanner::latencyTime() const
 {
     // The latency of a FFTConvolver is also fftSize() / 2, and is in addition to its tailTime of the
     // same value.
     return (fftSize() / 2) / static_cast<double>(sampleRate());
 }
 
 } // namespace blink