29 lines
781 B
C
29 lines
781 B
C
#include "../libfilter/iir_filter.h"
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typedef struct emphasis {
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struct {
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iir_filter_t lp;
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double x_last;
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double factor;
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double amp;
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} p;
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struct {
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iir_filter_t hp;
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double y_last;
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double factor;
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double amp;
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} d;
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} emphasis_t;
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/* refers to NMT specs, cnetz uses different emphasis cutoff */
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#define CUT_OFF_EMPHASIS_DEFAULT 300.0
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#define CUT_OFF_HIGHPASS_DEFAULT 300.0
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#define CUT_OFF_LOWPASS_DEFAULT 3400.0
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double timeconstant2cutoff(double time_constant_us);
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int init_emphasis(emphasis_t *state, int samplerate, double cut_off, double cut_off_h, double cut_off_l);
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void pre_emphasis(emphasis_t *state, sample_t *samples, int num);
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void de_emphasis(emphasis_t *state, sample_t *samples, int num);
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void dc_filter(emphasis_t *state, sample_t *samples, int num);
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