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add compressor

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KubaPro010
2025-03-01 21:00:56 +01:00
parent 8c9f6464b8
commit b513b98a9a
5 changed files with 278 additions and 15 deletions
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233
lib/filters.c
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@@ -77,4 +77,237 @@ float hard_clip(float sample, float threshold) {
} else {
return sample; // No clipping
}
}
float voltage_db_to_voltage(float db) {
return powf(10.0f, db / 20.0f);
}
float power_db_to_voltage(float db) {
return powf(10.0f, db / 10.0f);
}
float voltage_to_voltage_db(float linear) {
return 20.0f * log10f(fmaxf(linear, 1e-10f)); // Avoid log(0)
}
float voltage_to_power_db(float linear) {
return 10.0f * log10f(fmaxf(linear, 1e-10f)); // Avoid log(0)
}
void init_compressor(Compressor *compressor, float threshold, float ratio, float knee, float makeup_gain, float attack, float release, float rmsTime, float sample_rate) {
compressor->threshold = threshold;
compressor->ratio = ratio;
compressor->knee = knee;
compressor->makeup_gain = makeup_gain;
compressor->attack = attack;
compressor->release = release;
compressor->sample_rate = sample_rate;
compressor->gainReduction = 0.0f;
compressor->rmsEnv = 0.0f;
compressor->rmsTime = rmsTime;
}
float rms_compress(Compressor *compressor, float sample) {
float env;
float rmsAlpha = 1.0f - exp(-1.0f / (compressor->rmsTime * compressor->sample_rate));
compressor->rmsEnv = (1.0f - rmsAlpha) * compressor->rmsEnv + rmsAlpha * (sample * sample);
env = sqrtf(compressor->rmsEnv);
float input_db = voltage_to_voltage_db(env);
float targetGR = 0.0f;
if(input_db > compressor->threshold) {
if(compressor->knee > 0.0f) {
float delta = input_db - compressor->threshold;
if(delta < compressor->knee / 2.0f) {
targetGR = (1.0f - 1.0f / compressor->ratio) * (delta * delta) / compressor->knee;
} else {
targetGR = (1.0f - 1.0f / compressor->ratio) * delta;
}
} else {
targetGR = (1.0f - 1.0f / compressor->ratio) * (input_db - compressor->threshold);
}
} else {
targetGR = 0.0f;
}
float coeff;
if(targetGR > compressor->gainReduction) {
coeff = expf(-1.0f / (compressor->attack * compressor->sample_rate));
} else {
coeff = expf(-1.0f / (compressor->release * compressor->sample_rate));
}
compressor->gainReduction = coeff * compressor->gainReduction + (1.0f - coeff) * targetGR;
float gain = voltage_db_to_voltage(compressor->makeup_gain - compressor->gainReduction);
return sample * gain;
}
float peak_compress(Compressor *compressor, float sample) {
float env = fabsf(sample);
float input_db = voltage_to_voltage_db(env);
float targetGR = 0.0f;
if(input_db > compressor->threshold) {
if(compressor->knee > 0.0f) {
float delta = input_db - compressor->threshold;
if(delta < compressor->knee / 2.0f) {
targetGR = (1.0f - 1.0f / compressor->ratio) * (delta * delta) / compressor->knee;
} else {
targetGR = (1.0f - 1.0f / compressor->ratio) * delta;
}
} else {
targetGR = (1.0f - 1.0f / compressor->ratio) * (input_db - compressor->threshold);
}
} else {
targetGR = 0.0f;
}
float coeff;
if(targetGR > compressor->gainReduction) {
coeff = expf(-1.0f / (compressor->attack * compressor->sample_rate));
} else {
coeff = expf(-1.0f / (compressor->release * compressor->sample_rate));
}
compressor->gainReduction = coeff * compressor->gainReduction + (1.0f - coeff) * targetGR;
float gain = voltage_db_to_voltage(compressor->makeup_gain - compressor->gainReduction);
return sample * gain;
}
void init_compressor_stereo(StereoCompressor *compressor, float threshold, float ratio, float knee, float makeup_gain, float attack, float release, float rmsTime, float sample_rate) {
compressor->threshold = threshold;
compressor->ratio = ratio;
compressor->knee = knee;
compressor->makeup_gain = makeup_gain;
compressor->attack = attack;
compressor->release = release;
compressor->sample_rate = sample_rate;
compressor->gainReduction = 0.0f;
compressor->rmsEnv = 0.0f;
compressor->rmsEnv2 = 0.0f;
compressor->rmsTime = rmsTime;
}
float rms_compress_stereo(StereoCompressor *compressor, float l, float r, float *output_r) {
float env_l;
float env_r;
float rmsAlpha = 1.0f - exp(-1.0f / (compressor->rmsTime * compressor->sample_rate));
compressor->rmsEnv = (1.0f - rmsAlpha) * compressor->rmsEnv + rmsAlpha * (l * l);
compressor->rmsEnv2 = (1.0f - rmsAlpha) * compressor->rmsEnv + rmsAlpha * (r * r);
env_l = sqrtf(compressor->rmsEnv);
env_r = sqrtf(compressor->rmsEnv2);
float input_db = voltage_to_voltage_db(env_l);
float input_db_r = voltage_to_voltage_db(env_r);
float targetGR = 0.0f;
if(input_db > compressor->threshold) {
if(compressor->knee > 0.0f) {
float delta = input_db - compressor->threshold;
if(delta < compressor->knee / 2.0f) {
targetGR = (1.0f - 1.0f / compressor->ratio) * (delta * delta) / compressor->knee;
} else {
targetGR = (1.0f - 1.0f / compressor->ratio) * delta;
}
} else {
targetGR = (1.0f - 1.0f / compressor->ratio) * (input_db - compressor->threshold);
}
} else {
targetGR = 0.0f;
}
float targetGR_r = 0.0f;
if(input_db_r > compressor->threshold) {
if(compressor->knee > 0.0f) {
float delta = input_db_r - compressor->threshold;
if(delta < compressor->knee / 2.0f) {
targetGR_r = (1.0f - 1.0f / compressor->ratio) * (delta * delta) / compressor->knee;
} else {
targetGR_r = (1.0f - 1.0f / compressor->ratio) * delta;
}
} else {
targetGR_r = (1.0f - 1.0f / compressor->ratio) * (input_db_r - compressor->threshold);
}
} else {
targetGR_r = 0.0f;
}
float shared_target_gr;
if(targetGR > targetGR_r) {
shared_target_gr = targetGR;
} else {
shared_target_gr = targetGR_r;
}
float coeff;
if(shared_target_gr > compressor->gainReduction) {
coeff = expf(-1.0f / (compressor->attack * compressor->sample_rate));
} else {
coeff = expf(-1.0f / (compressor->release * compressor->sample_rate));
}
compressor->gainReduction = coeff * compressor->gainReduction + (1.0f - coeff) * shared_target_gr;
float gain = voltage_db_to_voltage(compressor->makeup_gain - compressor->gainReduction);
*output_r = r * gain;
return l * gain;
}
float peak_compress_stereo(StereoCompressor *compressor, float l, float r, float *output_r) {
float env_l = fabsf(l);
float env_r = fabsf(r);
float input_db = voltage_to_voltage_db(env_l);
float input_db_r = voltage_to_voltage_db(env_r);
float targetGR = 0.0f;
if(input_db > compressor->threshold) {
if(compressor->knee > 0.0f) {
float delta = input_db - compressor->threshold;
if(delta < compressor->knee / 2.0f) {
targetGR = (1.0f - 1.0f / compressor->ratio) * (delta * delta) / compressor->knee;
} else {
targetGR = (1.0f - 1.0f / compressor->ratio) * delta;
}
} else {
targetGR = (1.0f - 1.0f / compressor->ratio) * (input_db - compressor->threshold);
}
} else {
targetGR = 0.0f;
}
float targetGR_r = 0.0f;
if(input_db_r > compressor->threshold) {
if(compressor->knee > 0.0f) {
float delta = input_db_r - compressor->threshold;
if(delta < compressor->knee / 2.0f) {
targetGR_r = (1.0f - 1.0f / compressor->ratio) * (delta * delta) / compressor->knee;
} else {
targetGR_r = (1.0f - 1.0f / compressor->ratio) * delta;
}
} else {
targetGR_r = (1.0f - 1.0f / compressor->ratio) * (input_db_r - compressor->threshold);
}
} else {
targetGR_r = 0.0f;
}
float shared_target_gr;
if(targetGR > targetGR_r) {
shared_target_gr = targetGR;
} else {
shared_target_gr = targetGR_r;
}
float coeff;
if(shared_target_gr > compressor->gainReduction) {
coeff = expf(-1.0f / (compressor->attack * compressor->sample_rate));
} else {
coeff = expf(-1.0f / (compressor->release * compressor->sample_rate));
}
compressor->gainReduction = coeff * compressor->gainReduction + (1.0f - coeff) * shared_target_gr;
float gain = voltage_db_to_voltage(compressor->makeup_gain - compressor->gainReduction);
*output_r = r * gain;
return l * gain;
}