/*
* 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
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef HRTFPanner_h
#define HRTFPanner_h
#include "platform/audio/AudioDelayDSPKernel.h"
#include "platform/audio/FFTConvolver.h"
#include "platform/audio/HRTFDatabaseLoader.h"
#include "platform/audio/Panner.h"
namespace WebCore {
class PLATFORM_EXPORT HRTFPanner : public Panner {
public:
HRTFPanner(float sampleRate, HRTFDatabaseLoader*);
virtual ~HRTFPanner();
// Panner
virtual void pan(double azimuth, double elevation, const AudioBus* inputBus, AudioBus* outputBus, size_t framesToProcess) OVERRIDE;
virtual void reset() OVERRIDE;
size_t fftSize() const { return fftSizeForSampleRate(m_sampleRate); }
static size_t fftSizeForSampleRate(float sampleRate);
float sampleRate() const { return m_sampleRate; }
virtual double tailTime() const OVERRIDE;
virtual double latencyTime() const OVERRIDE;
private:
// Given an azimuth angle in the range -180 -> +180, returns the corresponding azimuth index for the database,
// and azimuthBlend which is an interpolation value from 0 -> 1.
int calculateDesiredAzimuthIndexAndBlend(double azimuth, double& azimuthBlend);
RefPtr<HRTFDatabaseLoader> m_databaseLoader;
float m_sampleRate;
// We maintain two sets of convolvers for smooth cross-faded interpolations when
// then azimuth and elevation are dynamically changing.
// When the azimuth and elevation are not changing, we simply process with one of the two sets.
// Initially we use CrossfadeSelection1 corresponding to m_convolverL1 and m_convolverR1.
// Whenever the azimuth or elevation changes, a crossfade is initiated to transition
// to the new position. So if we're currently processing with CrossfadeSelection1, then
// we transition to CrossfadeSelection2 (and vice versa).
// If we're in the middle of a transition, then we wait until it is complete before
// initiating a new transition.
// Selects either the convolver set (m_convolverL1, m_convolverR1) or (m_convolverL2, m_convolverR2).
enum CrossfadeSelection {
CrossfadeSelection1,
CrossfadeSelection2
};
CrossfadeSelection m_crossfadeSelection;
// azimuth/elevation for CrossfadeSelection1.
int m_azimuthIndex1;
double m_elevation1;
// azimuth/elevation for CrossfadeSelection2.
int m_azimuthIndex2;
double m_elevation2;
// A crossfade value 0 <= m_crossfadeX <= 1.
float m_crossfadeX;
// Per-sample-frame crossfade value increment.
float m_crossfadeIncr;
FFTConvolver m_convolverL1;
FFTConvolver m_convolverR1;
FFTConvolver m_convolverL2;
FFTConvolver m_convolverR2;
AudioDelayDSPKernel m_delayLineL;
AudioDelayDSPKernel m_delayLineR;
AudioFloatArray m_tempL1;
AudioFloatArray m_tempR1;
AudioFloatArray m_tempL2;
AudioFloatArray m_tempR2;
};
} // namespace WebCore
#endif // HRTFPanner_h