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refined oneknob compressor

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Chris
2025-07-31 16:26:40 +02:00
parent 90ce27a374
commit 9c7d9abc18
1 changed files with 36 additions and 37 deletions
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49
dynamics/oneknob.h
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@@ -63,49 +63,48 @@ inline void oneknob_init(oneknob_comp& comp, float samplerate, float window_ms)
{ {
rms_init(comp.detector, samplerate, window_ms); rms_init(comp.detector, samplerate, window_ms);
hp_filter_init(comp.filter, samplerate); hp_filter_init(comp.filter, samplerate);
comp.amount = 0.0f;
const float attack_ms = 10.f; const float attack_ms = 0.2f;
const float release_ms = 100.f; const float release_ms = 150.f;
comp.attack_coef = expf(-1.0f / (samplerate * (attack_ms * 0.001f))); comp.attack_coef = expf(-1.0f / (attack_ms * 1e-6 * samplerate));
comp.release_coef = expf(-1.0f / (samplerate * (release_ms * 0.001f))); comp.release_coef = expf(-1.0f / (release_ms * 1e-3 * samplerate));
comp.envelope_level = 0.f; comp.envelope_level = -60.f;
comp.sidechain_in = 0.f; comp.sidechain_in = 0.f;
} }
template <typename sample> template <typename sample>
inline void oneknob_process_block(oneknob_comp& comp, sample** audio, int frames) inline void oneknob_process_block(oneknob_comp& comp, sample** audio, int frames)
{ {
const float threshold = -18.f; const float min_user_ratio = 1.0f;
const float min_ratio = 1.0f; const float max_user_ratio = 20.0f;
const float max_ratio = 10.0f; const float threshold_db = -9.f;
float ratio = min_ratio + comp.amount * (max_ratio - min_ratio);
const float amount = fmaxf(0.0f, fminf(powf(comp.amount, 2.f), 1.0f)); // clamp to [0, 1]
float ratio = min_user_ratio + amount * (max_user_ratio - min_user_ratio);
for (int i = 0; i < frames; ++i) { for (int i = 0; i < frames; ++i) {
float rms_value = rms_process(comp.detector, comp.sidechain_in); float rms_value = rms_process(comp.detector, comp.sidechain_in);
float absolute_rms_db = lin_2_db(fabs(rms_value)); float envelope_in = lin_2_db(fmaxf(fabs(rms_value), 1e-20f));
// cut envelope below threshold // attack
float overshoot = absolute_rms_db - threshold; if (envelope_in > comp.envelope_level) {
if (overshoot < 0.f) overshoot = 0.f; comp.envelope_level = envelope_in + comp.attack_coef * (comp.envelope_level - envelope_in);
}
if (overshoot > comp.envelope_level) { // release
comp.envelope_level = overshoot + comp.attack_coef * (comp.envelope_level - overshoot); else {
} else { comp.envelope_level = envelope_in + comp.release_coef * (comp.envelope_level - envelope_in);
comp.envelope_level = overshoot + comp.release_coef * (comp.envelope_level - overshoot);
} }
if (comp.envelope_level < 0.f) comp.envelope_level = 0.f; float x = comp.envelope_level;
float y;
float slope = 1.f / ratio; if (x < threshold_db) y = x;
else y = threshold_db + (x - threshold_db) / ratio;
float gain_reduction_db = comp.envelope_level * (slope - 1.f); float gain_reduction_db = y - x;
float gain_reduction_lin = db_2_lin(gain_reduction_db); float gain_reduction_lin = db_2_lin(gain_reduction_db);
sample input_l = audio[0][i];
sample input_r = audio[1][i];
audio[0][i] *= gain_reduction_lin; audio[0][i] *= gain_reduction_lin;
audio[1][i] *= gain_reduction_lin; audio[1][i] *= gain_reduction_lin;