core/mixer.h

   1 #ifndef CORE_MIXER_H
   2 #define CORE_MIXER_H
   3
   4 #include <array>
   5 #include <cmath>
   6 #include <stddef.h>
   7 #include <type_traits>
   8
   9 #include "alspan.h"
  10 #include "ambidefs.h"
  11 #include "bufferline.h"
  12 #include "devformat.h"
  13
  14 struct MixParams;
  15
  16 /* Mixer functions that handle one input and multiple output channels. */
  17 using MixerOutFunc = void(*)(const al::span<const float> InSamples,
  18     const al::span<FloatBufferLine> OutBuffer, float *CurrentGains, const float *TargetGains,
  19     const size_t Counter, const size_t OutPos);
  20
  21 extern MixerOutFunc MixSamplesOut;
  22 inline void MixSamples(const al::span<const float> InSamples,
  23     const al::span<FloatBufferLine> OutBuffer, float *CurrentGains, const float *TargetGains,
  24     const size_t Counter, const size_t OutPos)
  25 { MixSamplesOut(InSamples, OutBuffer, CurrentGains, TargetGains, Counter, OutPos); }
  26
  27 /* Mixer functions that handle one input and one output channel. */
  28 using MixerOneFunc = void(*)(const al::span<const float> InSamples, float *OutBuffer,
  29     float &CurrentGain, const float TargetGain, const size_t Counter);
  30
  31 extern MixerOneFunc MixSamplesOne;
  32 inline void MixSamples(const al::span<const float> InSamples, float *OutBuffer, float &CurrentGain,
  33     const float TargetGain, const size_t Counter)
  34 { MixSamplesOne(InSamples, OutBuffer, CurrentGain, TargetGain, Counter); }
  35
  36
  37 /**
  38  * Calculates ambisonic encoder coefficients using the X, Y, and Z direction
  39  * components, which must represent a normalized (unit length) vector, and the
  40  * spread is the angular width of the sound (0...tau).
  41  *
  42  * NOTE: The components use ambisonic coordinates. As a result:
  43  *
  44  * Ambisonic Y = OpenAL -X
  45  * Ambisonic Z = OpenAL Y
  46  * Ambisonic X = OpenAL -Z
  47  *
  48  * The components are ordered such that OpenAL's X, Y, and Z are the first,
  49  * second, and third parameters respectively -- simply negate X and Z.
  50  */
  51 std::array<float,MaxAmbiChannels> CalcAmbiCoeffs(const float y, const float z, const float x,
  52     const float spread);
  53
  54 /**
  55  * CalcDirectionCoeffs
  56  *
  57  * Calculates ambisonic coefficients based on an OpenAL direction vector. The
  58  * vector must be normalized (unit length), and the spread is the angular width
  59  * of the sound (0...tau).
  60  */
  61 inline std::array<float,MaxAmbiChannels> CalcDirectionCoeffs(const float (&dir)[3],
  62     const float spread)
  63 {
  64     /* Convert from OpenAL coords to Ambisonics. */
  65     return CalcAmbiCoeffs(-dir[0], dir[1], -dir[2], spread);
  66 }
  67
  68 /**
  69  * CalcDirectionCoeffs
  70  *
  71  * Calculates ambisonic coefficients based on an OpenAL direction vector. The
  72  * vector must be normalized (unit length).
  73  */
  74 constexpr std::array<float,MaxAmbiChannels> CalcDirectionCoeffs(const float (&dir)[3])
  75 {
  76     /* Convert from OpenAL coords to Ambisonics. */
  77     return CalcAmbiCoeffs(-dir[0], dir[1], -dir[2]);
  78 }
  79
  80 /**
  81  * CalcAngleCoeffs
  82  *
  83  * Calculates ambisonic coefficients based on azimuth and elevation. The
  84  * azimuth and elevation parameters are in radians, going right and up
  85  * respectively.
  86  */
  87 inline std::array<float,MaxAmbiChannels> CalcAngleCoeffs(const float azimuth,
  88     const float elevation, const float spread)
  89 {
  90     const float x{-std::sin(azimuth) * std::cos(elevation)};
  91     const float y{ std::sin(elevation)};
  92     const float z{ std::cos(azimuth) * std::cos(elevation)};
  93
  94     return CalcAmbiCoeffs(x, y, z, spread);
  95 }
  96
  97
  98 /**
  99  * ComputePanGains
 100  *
 101  * Computes panning gains using the given channel decoder coefficients and the
 102  * pre-calculated direction or angle coefficients. For B-Format sources, the
 103  * coeffs are a 'slice' of a transform matrix for the input channel, used to
 104  * scale and orient the sound samples.
 105  */
 106 void ComputePanGains(const MixParams *mix, const float*RESTRICT coeffs, const float ingain,
 107     const al::span<float,MaxAmbiChannels> gains);
 108
 109 #endif /* CORE_MIXER_H */