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refactor filter functions and update FM modulator logic

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KubaPro010
2025-03-08 19:53:59 +01:00
parent 6acb8cd5da
commit 90fabff616
5 changed files with 12 additions and 40 deletions
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30
lib/filters.c
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@@ -24,35 +24,7 @@ void init_lpf(BiquadFilter* filter, float cutoffFreq, float qFactor, float sampl
filter->z2 = 0.0f;
}
void init_hpf(BiquadFilter* filter, float cutoffFreq, float qFactor, float sampleRate) {
float cutoffNorm = cutoffFreq / sampleRate;
float K = tanf(M_PI * cutoffNorm);
float norm = 1.0f/(1.0f+K/qFactor+K*K);
filter->a0 = 1.0f*norm;
filter->a1 = -2.0f*norm;
filter->a2 = 1.0f*norm;
filter->b1 = 2.0f*(K*K-1.0f)*norm;
filter->b2 = (1.0f-K/qFactor+K*K)*norm;
filter->z1 = 0.0f;
filter->z2 = 0.0f;
}
void init_bpf(BiquadFilter* filter, float centerFreq, float qFactor, float sampleRate) {
float cutoffNorm = centerFreq / sampleRate;
float K = tanf(M_PI * cutoffNorm);
float norm = 1.0f/(1.0f+K/qFactor+K*K);
filter->a0 = K/qFactor*norm;
filter->a1 = 0.0f;
filter->a2 = -K/qFactor*norm;
filter->b1 = 2.0f*(K*K-1.0f)*norm;
filter->b2 = (1.0f-K/qFactor+K*K)*norm;
filter->z1 = 0.0f;
filter->z2 = 0.0f;
}
float apply_frequency_filter(BiquadFilter* filter, float input) {
float apply_biquad(BiquadFilter* filter, float input) {
float out = input*filter->a0+filter->z1;
filter->z1 = input*filter->a1+filter->z2-filter->b1*out;
filter->z2 = input*filter->a2-filter->b2*out;