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#ifndef NFCFILTER_H
#define NFCFILTER_H
#include "alMain.h"
struct NfcFilter1 {
float g;
float coeffs[1*2 + 1];
float history[1];
};
struct NfcFilter2 {
float g;
float coeffs[2*2 + 1];
float history[2];
};
struct NfcFilter3 {
float g;
float coeffs[3*2 + 1];
float history[3];
};
typedef struct NfcFilter {
struct NfcFilter1 first;
struct NfcFilter2 second;
struct NfcFilter3 third;
} NfcFilter;
/* NOTE:
* w0 = speed_of_sound / (source_distance * sample_rate);
* w1 = speed_of_sound / (control_distance * sample_rate);
*
* Generally speaking, the control distance should be approximately the average
* speaker distance, or based on the reference delay if outputing NFC-HOA. It
* must not be negative, 0, or infinite. The source distance should not be too
* small relative to the control distance.
*/
void NfcFilterCreate(NfcFilter *nfc, const float w0, const float w1);
void NfcFilterAdjust(NfcFilter *nfc, const float w0);
/* Near-field control filter for first-order ambisonic channels (1-3). */
void NfcFilterUpdate1(NfcFilter *nfc, float *restrict dst, const float *restrict src, const int count);
/* Near-field control filter for second-order ambisonic channels (4-8). */
void NfcFilterUpdate2(NfcFilter *nfc, float *restrict dst, const float *restrict src, const int count);
/* Near-field control filter for third-order ambisonic channels (9-15). */
void NfcFilterUpdate3(NfcFilter *nfc, float *restrict dst, const float *restrict src, const int count);
#endif /* NFCFILTER_H */
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