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turn lpf and emphasis into a common rc

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KubaPro010
2025-01-21 14:32:50 +01:00
parent 1fef2f7598
commit 3ac9d67e3d
12 changed files with 40 additions and 45 deletions
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24
lib/filters.c
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@@ -1,25 +1,23 @@
#include "filters.h"
void init_emphasis(Emphasis *pe, float tau, float sample_rate) {
pe->prev_sample = 0.0f;
pe->alpha = exp(-1 / (tau * sample_rate));
void init_rc(ResistorCapacitor *rc, float tau, float sample_rate) {
rc->prev_sample = 0.0f;
rc->alpha = exp(-1 / (tau * sample_rate));
}
float apply_pre_emphasis(Emphasis *pe, float sample) {
float audio = sample-pe->alpha*pe->prev_sample;
pe->prev_sample = audio;
float apply_pre_emphasis(ResistorCapacitor *rc, float sample) {
float audio = sample-rc->alpha*rc->prev_sample;
rc->prev_sample = audio;
return audio*2;
}
void init_low_pass_filter(LowPassFilter *lp, float cutoff_frequency, float sample_rate) {
float rc = 1/(M_2PI*cutoff_frequency);
lp->alpha = sample_rate/(sample_rate+rc);
lp->prev_sample = 0.0f;
void init_low_pass_filter(ResistorCapacitor *rc, float cutoff_frequency, float sample_rate) {
init_rc(&rc, (-1 / (sample_rate * log(sample_rate/(sample_rate+(1/(M_2PI*cutoff_frequency)))))), sample_rate);
}
float apply_low_pass_filter(LowPassFilter *lp, float sample) {
float output = lp->alpha*sample+(1-lp->alpha)*lp->prev_sample;
lp->prev_sample = output;
float apply_low_pass_filter(ResistorCapacitor *rc, float sample) {
float output = rc->alpha*sample+(1-rc->alpha)*rc->prev_sample;
rc->prev_sample = output;
return output;
}