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

/*
 * Copyright (C) 2010 Google Inc. All rights reserved.
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 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
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#ifndef HRTFElevation_h
#define HRTFElevation_h

#include "platform/audio/HRTFKernel.h"
#include "wtf/Allocator.h"
#include "wtf/Noncopyable.h"
#include "wtf/PassRefPtr.h"
#include "wtf/RefPtr.h"
#include "wtf/text/CString.h"
#include "wtf/text/WTFString.h"
#include <memory>

namespace blink {

// HRTFElevation contains all of the HRTFKernels (one left ear and one right ear
// per azimuth angle) for a particular elevation.

class PLATFORM_EXPORT HRTFElevation {
  USING_FAST_MALLOC(HRTFElevation);
  WTF_MAKE_NONCOPYABLE(HRTFElevation);

 public:
  // Loads and returns an HRTFElevation with the given HRTF database subject
  // name and elevation from browser (or WebKit.framework) resources.
  // Normally, there will only be a single HRTF database set, but this API
  // supports the possibility of multiple ones with different names.
  // Interpolated azimuths will be generated based on InterpolationFactor.
  // Valid values for elevation are -45 -> +90 in 15 degree increments.
  static std::unique_ptr<HRTFElevation>
  createForSubject(const String& subjectName, int elevation, float sampleRate);

  // Given two HRTFElevations, and an interpolation factor x: 0 -> 1, returns an
  // interpolated HRTFElevation.
  static std::unique_ptr<HRTFElevation> createByInterpolatingSlices(
      HRTFElevation* hrtfElevation1,
      HRTFElevation* hrtfElevation2,
      float x,
      float sampleRate);

  // Returns the list of left or right ear HRTFKernels for all the azimuths
  // going from 0 to 360 degrees.
  HRTFKernelList* kernelListL() { return m_kernelListL.get(); }
  HRTFKernelList* kernelListR() { return m_kernelListR.get(); }

  double elevationAngle() const { return m_elevationAngle; }
  unsigned numberOfAzimuths() const { return NumberOfTotalAzimuths; }
  float sampleRate() const { return m_sampleRate; }

  // Returns the left and right kernels for the given azimuth index.
  // The interpolated delays based on azimuthBlend: 0 -> 1 are returned in
  // frameDelayL and frameDelayR.
  void getKernelsFromAzimuth(double azimuthBlend,
                             unsigned azimuthIndex,
                             HRTFKernel*& kernelL,
                             HRTFKernel*& kernelR,
                             double& frameDelayL,
                             double& frameDelayR);

  // Spacing, in degrees, between every azimuth loaded from resource.
  static const unsigned AzimuthSpacing;

  // Number of azimuths loaded from resource.
  static const unsigned NumberOfRawAzimuths;

  // Interpolates by this factor to get the total number of azimuths from every
  // azimuth loaded from resource.
  static const unsigned InterpolationFactor;

  // Total number of azimuths after interpolation.
  static const unsigned NumberOfTotalAzimuths;

  // Given a specific azimuth and elevation angle, returns the left and right
  // HRTFKernel.
  // Valid values for azimuth are 0 -> 345 in 15 degree increments.
  // Valid values for elevation are -45 -> +90 in 15 degree increments.
  // Returns true on success.
  static bool calculateKernelsForAzimuthElevation(
      int azimuth,
      int elevation,
      float sampleRate,
      const String& subjectName,
      std::unique_ptr<HRTFKernel>& kernelL,
      std::unique_ptr<HRTFKernel>& kernelR);

 private:
  HRTFElevation(std::unique_ptr<HRTFKernelList> kernelListL,
                std::unique_ptr<HRTFKernelList> kernelListR,
                int elevation,
                float sampleRate)
      : m_kernelListL(std::move(kernelListL)),
        m_kernelListR(std::move(kernelListR)),
        m_elevationAngle(elevation),
        m_sampleRate(sampleRate) {}

  std::unique_ptr<HRTFKernelList> m_kernelListL;
  std::unique_ptr<HRTFKernelList> m_kernelListR;
  double m_elevationAngle;
  float m_sampleRate;
};

}  // namespace blink

#endif  // HRTFElevation_h