OpenAL32/Include/alFilter.h

   1 #ifndef _AL_FILTER_H_
   2 #define _AL_FILTER_H_
   3
   4 #include "alMain.h"
   5
   6 #ifdef __cplusplus
   7 extern "C" {
   8 #endif
   9
  10 #define LOWPASSFREQREF  (5000.0f)
  11 #define HIGHPASSFREQREF  (250.0f)
  12
  13
  14 /* Filters implementation is based on the "Cookbook formulae for audio   *
  15  * EQ biquad filter coefficients" by Robert Bristow-Johnson              *
  16  * http://www.musicdsp.org/files/Audio-EQ-Cookbook.txt                   */
  17
  18 typedef enum ALfilterType {
  19     /** EFX-style low-pass filter, specifying a gain and reference frequency. */
  20     ALfilterType_HighShelf,
  21     /** EFX-style high-pass filter, specifying a gain and reference frequency. */
  22     ALfilterType_LowShelf,
  23     /** Peaking filter, specifying a gain, reference frequency, and bandwidth. */
  24     ALfilterType_Peaking,
  25
  26     /** Low-pass cut-off filter, specifying a cut-off frequency and bandwidth. */
  27     ALfilterType_LowPass,
  28     /** High-pass cut-off filter, specifying a cut-off frequency and bandwidth. */
  29     ALfilterType_HighPass,
  30     /** Band-pass filter, specifying a center frequency and bandwidth. */
  31     ALfilterType_BandPass,
  32 } ALfilterType;
  33
  34 typedef struct ALfilterState {
  35     ALfloat x[2]; /* History of two last input samples  */
  36     ALfloat y[2]; /* History of two last output samples */
  37     ALfloat a[3]; /* Transfer function coefficients "a" */
  38     ALfloat b[3]; /* Transfer function coefficients "b" */
  39
  40     void (*process)(struct ALfilterState *self, ALfloat *restrict dst, const ALfloat *src, ALuint numsamples);
  41 } ALfilterState;
  42 #define ALfilterState_process(a, ...) ((a)->process((a), __VA_ARGS__))
  43
  44 void ALfilterState_clear(ALfilterState *filter);
  45 void ALfilterState_setParams(ALfilterState *filter, ALfilterType type, ALfloat gain, ALfloat freq_mult, ALfloat bandwidth);
  46
  47 inline ALfloat ALfilterState_processSingle(ALfilterState *filter, ALfloat sample)
  48 {
  49     ALfloat outsmp;
  50
  51     outsmp = filter->b[0] * sample +
  52              filter->b[1] * filter->x[0] +
  53              filter->b[2] * filter->x[1] -
  54              filter->a[1] * filter->y[0] -
  55              filter->a[2] * filter->y[1];
  56     filter->x[1] = filter->x[0];
  57     filter->x[0] = sample;
  58     filter->y[1] = filter->y[0];
  59     filter->y[0] = outsmp;
  60
  61     return outsmp;
  62 }
  63
  64 void ALfilterState_processC(ALfilterState *filter, ALfloat *restrict dst, const ALfloat *src, ALuint numsamples);
  65
  66
  67 typedef struct ALfilter {
  68     // Filter type (AL_FILTER_NULL, ...)
  69     ALenum type;
  70
  71     ALfloat Gain;
  72     ALfloat GainHF;
  73     ALfloat HFReference;
  74     ALfloat GainLF;
  75     ALfloat LFReference;
  76
  77     void (*SetParami)(struct ALfilter *filter, ALCcontext *context, ALenum param, ALint val);
  78     void (*SetParamiv)(struct ALfilter *filter, ALCcontext *context, ALenum param, const ALint *vals);
  79     void (*SetParamf)(struct ALfilter *filter, ALCcontext *context, ALenum param, ALfloat val);
  80     void (*SetParamfv)(struct ALfilter *filter, ALCcontext *context, ALenum param, const ALfloat *vals);
  81
  82     void (*GetParami)(struct ALfilter *filter, ALCcontext *context, ALenum param, ALint *val);
  83     void (*GetParamiv)(struct ALfilter *filter, ALCcontext *context, ALenum param, ALint *vals);
  84     void (*GetParamf)(struct ALfilter *filter, ALCcontext *context, ALenum param, ALfloat *val);
  85     void (*GetParamfv)(struct ALfilter *filter, ALCcontext *context, ALenum param, ALfloat *vals);
  86
  87     /* Self ID */
  88     ALuint id;
  89 } ALfilter;
  90
  91 #define ALfilter_SetParami(x, c, p, v)  ((x)->SetParami((x),(c),(p),(v)))
  92 #define ALfilter_SetParamiv(x, c, p, v) ((x)->SetParamiv((x),(c),(p),(v)))
  93 #define ALfilter_SetParamf(x, c, p, v)  ((x)->SetParamf((x),(c),(p),(v)))
  94 #define ALfilter_SetParamfv(x, c, p, v) ((x)->SetParamfv((x),(c),(p),(v)))
  95
  96 #define ALfilter_GetParami(x, c, p, v)  ((x)->GetParami((x),(c),(p),(v)))
  97 #define ALfilter_GetParamiv(x, c, p, v) ((x)->GetParamiv((x),(c),(p),(v)))
  98 #define ALfilter_GetParamf(x, c, p, v)  ((x)->GetParamf((x),(c),(p),(v)))
  99 #define ALfilter_GetParamfv(x, c, p, v) ((x)->GetParamfv((x),(c),(p),(v)))
 100
 101 inline struct ALfilter *LookupFilter(ALCdevice *device, ALuint id)
 102 { return (struct ALfilter*)LookupUIntMapKey(&device->FilterMap, id); }
 103 inline struct ALfilter *RemoveFilter(ALCdevice *device, ALuint id)
 104 { return (struct ALfilter*)RemoveUIntMapKey(&device->FilterMap, id); }
 105
 106 ALvoid ReleaseALFilters(ALCdevice *device);
 107
 108 #ifdef __cplusplus
 109 }
 110 #endif
 111
 112 #endif