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      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 "core/platform/audio/FFTConvolver.h"
     29 #include "core/platform/audio/HRTFDatabaseLoader.h"
     30 #include "core/platform/audio/Panner.h"
     31 #include "modules/webaudio/DelayDSPKernel.h"
     32 
     33 namespace WebCore {
     34 
     35 class HRTFPanner : public Panner {
     36 public:
     37     HRTFPanner(float sampleRate, HRTFDatabaseLoader*);
     38     virtual ~HRTFPanner();
     39 
     40     // Panner
     41     virtual void pan(double azimuth, double elevation, const AudioBus* inputBus, AudioBus* outputBus, size_t framesToProcess);
     42     virtual void reset();
     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     virtual double tailTime() const OVERRIDE;
     50     virtual 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     DelayDSPKernel m_delayLineL;
     99     DelayDSPKernel m_delayLineR;
    100 
    101     AudioFloatArray m_tempL1;
    102     AudioFloatArray m_tempR1;
    103     AudioFloatArray m_tempL2;
    104     AudioFloatArray m_tempR2;
    105 };
    106 
    107 } // namespace WebCore
    108 
    109 #endif // HRTFPanner_h
    110