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Kuba
2025-08-08 23:00:33 +02:00
committed by GitHub
parent d6a4d71042
commit f2c96ee0f2
1 changed files with 11 additions and 16 deletions
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27
filter/iir.c
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@@ -16,26 +16,21 @@ inline float apply_preemphasis(ResistorCapacitor *filter, float sample) {
}
void tilt_init(TiltCorrectionFilter* filter, float alpha) {
// Leaky integrator for DC estimation: dc[n] = alpha*dc[n-1] + (1-alpha)*x[n]
// Tilt correction: y[n] = x[n] - dc[n]
if (alpha >= 1.0f) {
alpha = 0.99999f;
}
if (alpha < 0.0f) {
alpha = 0.0f;
}
filter->alpha = alpha; // Leaky integrator coefficient
filter->dc_estimate = 0.0f; // Running DC estimate
// Allow correction_strength > 1.0 for aggressive correction
filter->alpha = 0.9999f; // Fixed time constant for DC tracking
filter->gain = alpha; // Separate gain parameter
filter->dc_estimate = 0.0f;
}
float tilt(TiltCorrectionFilter* filter, float input) {
// Update DC estimate using leaky integrator
float tilt_correct(TiltCorrectionFilter* filter, float input) {
// Track the baseline/DC level
filter->dc_estimate = filter->alpha * filter->dc_estimate + (1.0f - filter->alpha) * input;
// ADD the DC estimate instead of subtracting
float output = input + (input - filter->dc_estimate) * correction_factor;
// Calculate the deviation from baseline
float deviation = input - filter->dc_estimate;
// Apply correction gain and add back to baseline
float output = filter->dc_estimate + deviation * filter->gain;
return output;
}