radio95/fm95
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small changes

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This commit is contained in:
KubaPro010
2025-03-02 09:25:50 +01:00
parent 3cf6c4ef82
commit 1d2bedb06b
4 changed files with 31 additions and 3 deletions
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26
lib/filters.c
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@@ -60,6 +60,32 @@ void init_hpf(BiquadFilter* filter, float cutoffFreq, float qFactor, float sampl
filter->a2 = -_a2/_a0;
}
void init_bpf(BiquadFilter* filter, float centerFreq, float qFactor, float sampleRate) {
float x = (centerFreq * M_2PI) / sampleRate;
float sinX = sin(x);
float cosX = cos(x);
float alpha = sinX / (2.0f * qFactor);
float _a0 = 1.0f + alpha;
float _a1 = -2.0f * cosX;
float _a2 = 1.0f - alpha;
float _b0 = alpha;
float _b1 = 0.0f;
float _b2 = -alpha;
filter->y2 = 0;
filter->y1 = 0;
filter->x2 = 0;
filter->x1 = 0;
filter->b0 = _b0 / _a0;
filter->b1 = _b1 / _a0;
filter->b2 = _b2 / _a0;
filter->a1 = -_a1 / _a0;
filter->a2 = -_a2 / _a0;
}
float apply_frequency_filter(BiquadFilter* filter, float input) {
float out = input*filter->b0+filter->x1*filter->b1+filter->x2*filter->b2+filter->y1*filter->a1+filter->y2*filter->a2;
filter->y2 = filter->y1;

1
lib/filters.h
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@@ -22,6 +22,7 @@ typedef struct {
} BiquadFilter;
void init_lpf(BiquadFilter* filter, float cutoffFreq, float qFactor, float sampleRate);
void init_hpf(BiquadFilter* filter, float cutoffFreq, float qFactor, float sampleRate);
void init_bpf(BiquadFilter* filter, float centerFreq, float qFactor, float sampleRate);
float apply_frequency_filter(BiquadFilter* filter, float input);
float hard_clip(float sample, float threshold);