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

   1 /*
   2  * Copyright (C) 2010, Google Inc. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
   6  * are met:
   7  * 1.  Redistributions of source code must retain the above copyright
   8  *    notice, this list of conditions and the following disclaimer.
   9  * 2.  Redistributions in binary form must reproduce the above copyright
  10  *    notice, this list of conditions and the following disclaimer in the
  11  *    documentation and/or other materials provided with the distribution.
  12  *
  13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
  14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  15  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  16  * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
  17  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  18  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  19  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
  20  * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  21  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  22  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  23  */
  24
  25 #ifndef HRTFPanner_h
  26 #define HRTFPanner_h
  27
  28 #include "platform/audio/AudioDelayDSPKernel.h"
  29 #include "platform/audio/FFTConvolver.h"
  30 #include "platform/audio/HRTFDatabaseLoader.h"
  31 #include "platform/audio/Panner.h"
  32
  33 namespace blink {
  34
  35 class PLATFORM_EXPORT HRTFPanner final : public Panner {
  36 public:
  37     HRTFPanner(float sampleRate, HRTFDatabaseLoader*);
  38     ~HRTFPanner() override;
  39
  40     // Panner
  41     void pan(double azimuth, double elevation, const AudioBus* inputBus, AudioBus* outputBus, size_t framesToProcess) override;
  42     void reset() override;
  43
  44     size_t fftSize() const { return fftSizeForSampleRate(m_sampleRate); }
  45     static size_t fftSizeForSampleRate(float sampleRate);
  46
  47     float sampleRate() const { return m_sampleRate; }
  48
  49     double tailTime() const override;
  50     double latencyTime() const override;
  51
  52 private:
  53     // Given an azimuth angle in the range -180 -> +180, returns the corresponding azimuth index for the database,
  54     // and azimuthBlend which is an interpolation value from 0 -> 1.
  55     int calculateDesiredAzimuthIndexAndBlend(double azimuth, double& azimuthBlend);
  56
  57     RefPtr<HRTFDatabaseLoader> m_databaseLoader;
  58
  59     float m_sampleRate;
  60
  61     // We maintain two sets of convolvers for smooth cross-faded interpolations when
  62     // then azimuth and elevation are dynamically changing.
  63     // When the azimuth and elevation are not changing, we simply process with one of the two sets.
  64     // Initially we use CrossfadeSelection1 corresponding to m_convolverL1 and m_convolverR1.
  65     // Whenever the azimuth or elevation changes, a crossfade is initiated to transition
  66     // to the new position. So if we're currently processing with CrossfadeSelection1, then
  67     // we transition to CrossfadeSelection2 (and vice versa).
  68     // If we're in the middle of a transition, then we wait until it is complete before
  69     // initiating a new transition.
  70
  71     // Selects either the convolver set (m_convolverL1, m_convolverR1) or (m_convolverL2, m_convolverR2).
  72     enum CrossfadeSelection {
  73         CrossfadeSelection1,
  74         CrossfadeSelection2
  75     };
  76
  77     CrossfadeSelection m_crossfadeSelection;
  78
  79     // azimuth/elevation for CrossfadeSelection1.
  80     int m_azimuthIndex1;
  81     double m_elevation1;
  82
  83     // azimuth/elevation for CrossfadeSelection2.
  84     int m_azimuthIndex2;
  85     double m_elevation2;
  86
  87     // A crossfade value 0 <= m_crossfadeX <= 1.
  88     float m_crossfadeX;
  89
  90     // Per-sample-frame crossfade value increment.
  91     float m_crossfadeIncr;
  92
  93     FFTConvolver m_convolverL1;
  94     FFTConvolver m_convolverR1;
  95     FFTConvolver m_convolverL2;
  96     FFTConvolver m_convolverR2;
  97
  98     AudioDelayDSPKernel m_delayLineL;
  99     AudioDelayDSPKernel m_delayLineR;
 100
 101     AudioFloatArray m_tempL1;
 102     AudioFloatArray m_tempR1;
 103     AudioFloatArray m_tempL2;
 104     AudioFloatArray m_tempR2;
 105 };
 106
 107 } // namespace blink
 108
 109 #endif // HRTFPanner_h