alc/hrtf.h

   1 #ifndef ALC_HRTF_H
   2 #define ALC_HRTF_H
   3
   4 #include <array>
   5 #include <cstddef>
   6 #include <memory>
   7 #include <string>
   8
   9 #include "AL/al.h"
  10
  11 #include "almalloc.h"
  12 #include "alspan.h"
  13 #include "ambidefs.h"
  14 #include "atomic.h"
  15 #include "vector.h"
  16
  17 struct HrtfHandle;
  18
  19
  20 #define HRTF_HISTORY_BITS   (6)
  21 #define HRTF_HISTORY_LENGTH (1<<HRTF_HISTORY_BITS)
  22 #define HRTF_HISTORY_MASK   (HRTF_HISTORY_LENGTH-1)
  23
  24 #define HRIR_BITS        (7)
  25 #define HRIR_LENGTH      (1<<HRIR_BITS)
  26 #define HRIR_MASK        (HRIR_LENGTH-1)
  27
  28
  29 struct HrtfEntry {
  30     RefCount mRef;
  31
  32     ALuint sampleRate;
  33     ALuint irSize;
  34
  35     struct Field {
  36         ALfloat distance;
  37         ALubyte evCount;
  38     };
  39     /* NOTE: Fields are stored *backwards*. field[0] is the farthest field, and
  40      * field[fdCount-1] is the nearest.
  41      */
  42     ALuint fdCount;
  43     const Field *field;
  44
  45     struct Elevation {
  46         ALushort azCount;
  47         ALushort irOffset;
  48     };
  49     Elevation *elev;
  50     const ALfloat (*coeffs)[2];
  51     const ALubyte (*delays)[2];
  52
  53     void IncRef();
  54     void DecRef();
  55
  56     DEF_PLACE_NEWDEL()
  57 };
  58
  59 struct EnumeratedHrtf {
  60     std::string name;
  61
  62     HrtfHandle *hrtf;
  63 };
  64
  65
  66 using float2 = std::array<float,2>;
  67 using HrirArray = std::array<float2,HRIR_LENGTH>;
  68
  69 struct HrtfState {
  70     alignas(16) std::array<ALfloat,HRTF_HISTORY_LENGTH> History;
  71     alignas(16) HrirArray Values;
  72 };
  73
  74 struct HrtfFilter {
  75     alignas(16) HrirArray Coeffs;
  76     ALsizei Delay[2];
  77     ALfloat Gain;
  78 };
  79
  80 struct DirectHrtfState {
  81     /* HRTF filter state for dry buffer content */
  82     ALuint IrSize{0};
  83     alignas(16) HrirArray Values{};
  84     al::FlexArray<HrirArray,16> Coeffs;
  85
  86     DirectHrtfState(size_t numchans) : Coeffs{numchans} { }
  87
  88     static std::unique_ptr<DirectHrtfState> Create(size_t num_chans);
  89
  90     DEF_FAM_NEWDEL(DirectHrtfState, Coeffs)
  91 };
  92
  93 struct AngularPoint {
  94     ALfloat Elev;
  95     ALfloat Azim;
  96 };
  97
  98
  99 al::vector<EnumeratedHrtf> EnumerateHrtf(const char *devname);
 100 HrtfEntry *GetLoadedHrtf(HrtfHandle *handle);
 101
 102 void GetHrtfCoeffs(const HrtfEntry *Hrtf, ALfloat elevation, ALfloat azimuth, ALfloat distance,
 103     ALfloat spread, HrirArray &coeffs, ALsizei (&delays)[2]);
 104
 105 /**
 106  * Produces HRTF filter coefficients for decoding B-Format, given a set of
 107  * virtual speaker positions, a matching decoding matrix, and per-order high-
 108  * frequency gains for the decoder. The calculated impulse responses are
 109  * ordered and scaled according to the matrix input.
 110  */
 111 void BuildBFormatHrtf(const HrtfEntry *Hrtf, DirectHrtfState *state,
 112     const al::span<const AngularPoint> AmbiPoints, const ALfloat (*AmbiMatrix)[MAX_AMBI_CHANNELS],
 113     const ALfloat *AmbiOrderHFGain);
 114
 115 #endif /* ALC_HRTF_H */