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