Alc/hrtf.h


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56

#ifndef ALC_HRTF_H
#define ALC_HRTF_H

#include "AL/al.h"
#include "AL/alc.h"

#include "alMain.h"
#include "alstring.h"
#include "atomic.h"


#define HRTFDELAY_BITS    (20)
#define HRTFDELAY_FRACONE (1<<HRTFDELAY_BITS)
#define HRTFDELAY_MASK    (HRTFDELAY_FRACONE-1)

/* The maximum number of virtual speakers used to generate HRTF coefficients
 * for decoding B-Format.
 */
#define HRTF_AMBI_MAX_CHANNELS 16


struct HrtfEntry;

struct Hrtf {
    RefCount ref;

    ALuint sampleRate;
    ALsizei irSize;
    ALubyte evCount;

    const ALubyte *azCount;
    const ALushort *evOffset;
    const ALfloat (*coeffs)[2];
    const ALubyte (*delays)[2];
};


void FreeHrtfs(void);

vector_EnumeratedHrtf EnumerateHrtf(const_al_string devname);
void FreeHrtfList(vector_EnumeratedHrtf *list);
struct Hrtf *GetLoadedHrtf(struct HrtfEntry *entry);
void Hrtf_IncRef(struct Hrtf *hrtf);
void Hrtf_DecRef(struct Hrtf *hrtf);

void GetHrtfCoeffs(const struct Hrtf *Hrtf, ALfloat elevation, ALfloat azimuth, ALfloat spread, ALfloat (*coeffs)[2], ALsizei *delays);

/**
 * Produces HRTF filter coefficients for decoding B-Format, given a set of
 * virtual speaker positions and HF/LF matrices for decoding to them. The
 * returned coefficients are ordered and scaled according to the matrices.
 * Returns the maximum impulse-response length of the generated coefficients.
 */
ALsizei BuildBFormatHrtf(const struct Hrtf *Hrtf, DirectHrtfState *state, ALsizei NumChannels, const ALfloat (*restrict AmbiPoints)[2], const ALfloat (*restrict AmbiMatrix)[2][MAX_AMBI_COEFFS], ALsizei AmbiCount);

#endif /* ALC_HRTF_H */