144 lines
3.7 KiB
C++
144 lines
3.7 KiB
C++
#pragma once
|
|
|
|
namespace trnr {
|
|
template <typename sample>
|
|
class pump {
|
|
public:
|
|
pump()
|
|
: attack_ms(10.f)
|
|
, release_ms(100.f)
|
|
, hp_filter(80.0f)
|
|
, threshold_db(0.f)
|
|
, ratio(1000.0f)
|
|
, filter_frq(40000.f)
|
|
, filter_exp(0.f)
|
|
, treble_boost(0.f)
|
|
{
|
|
set_samplerate(44100);
|
|
}
|
|
|
|
void set_samplerate(double _samplerate)
|
|
{
|
|
samplerate = _samplerate;
|
|
set_attack(attack_ms);
|
|
set_release(release_ms);
|
|
}
|
|
|
|
void set_ratio(float value) { ratio = value; }
|
|
|
|
/* set threshold in db */
|
|
void set_threshold(float value) { threshold_db = value; }
|
|
|
|
/* set attack in ms */
|
|
void set_attack(float value)
|
|
{
|
|
attack_ms = value;
|
|
attack_coef = exp(-1000.0 / (attack_ms * samplerate));
|
|
}
|
|
|
|
/* set release in ms */
|
|
void set_release(float value)
|
|
{
|
|
release_ms = value;
|
|
release_coef = exp(-1000.0 / (release_ms * samplerate));
|
|
}
|
|
|
|
/* lowpass filter frequency in hz */
|
|
void set_filter_frq(float value) { filter_frq = value; }
|
|
|
|
/* accentuates the filter pumping effect */
|
|
void set_filter_exp(float value) { filter_exp = value; }
|
|
|
|
void process_block(sample** audio, sample** sidechain, uint frames)
|
|
{
|
|
// highpass filter coefficients
|
|
float hp_x = std::exp(-2.0 * M_PI * hp_filter / samplerate);
|
|
float hp_a0 = 1.0 - hp_x;
|
|
float hp_b1 = -hp_x;
|
|
|
|
// top end boost filter coefficients
|
|
float bst_x = exp(-2.0 * M_PI * 5000.0 / samplerate);
|
|
float bst_a0 = 1.0 - bst_x;
|
|
float bst_b1 = -bst_x;
|
|
|
|
for (uint i = 0; i < frames; i++) {
|
|
|
|
sample input_l = audio[0][i];
|
|
sample input_r = audio[1][i];
|
|
|
|
sample sidechain_in = (sidechain[0][i] + sidechain[1][i]) / 2.0;
|
|
|
|
// highpass filter sidechain signal
|
|
filtered = hp_a0 * sidechain_in - hp_b1 * filtered;
|
|
sidechain_in = sidechain_in - filtered;
|
|
|
|
// rectify sidechain input for envelope following
|
|
float link = std::fabs(sidechain_in);
|
|
float linked_db = trnr::lin_2_db(link);
|
|
|
|
// cut envelope below threshold
|
|
float overshoot_db = linked_db - (threshold_db - 10.0);
|
|
if (overshoot_db < 0.0) overshoot_db = 0.0;
|
|
|
|
// process envelope
|
|
if (overshoot_db > envelope_db) {
|
|
envelope_db = overshoot_db + attack_coef * (envelope_db - overshoot_db);
|
|
} else {
|
|
envelope_db = overshoot_db + release_coef * (envelope_db - overshoot_db);
|
|
}
|
|
|
|
float slope = 1.f / ratio;
|
|
|
|
// transfer function
|
|
float gain_reduction_db = envelope_db * (slope - 1.0);
|
|
float gain_reduction_lin = trnr::db_2_lin(gain_reduction_db);
|
|
|
|
// compress left and right signals
|
|
sample output_l = input_l * gain_reduction_lin;
|
|
sample output_r = input_r * gain_reduction_lin;
|
|
|
|
if (filter_exp > 0.f) {
|
|
// one pole lowpass filter with envelope applied to frequency for pumping effect
|
|
float freq = filter_frq * pow(gain_reduction_lin, filter_exp);
|
|
float lp_x = exp(-2.0 * M_PI * freq / samplerate);
|
|
float lp_a0 = 1.0 - lp_x;
|
|
float lp_b1 = -lp_x;
|
|
filtered_l = lp_a0 * output_l - lp_b1 * filtered_l;
|
|
filtered_r = lp_a0 * output_r - lp_b1 * filtered_r;
|
|
}
|
|
|
|
// top end boost
|
|
boosted_l = bst_a0 * filtered_l - bst_b1 * boosted_l;
|
|
boosted_r = bst_a0 * filtered_r - bst_b1 * boosted_r;
|
|
output_l = filtered_l + (filtered_l - boosted_l) * treble_boost;
|
|
output_r = filtered_r + (filtered_r - boosted_r) * treble_boost;
|
|
|
|
// calculate makeup gain
|
|
float makeup_lin = trnr::db_2_lin(-threshold_db / 5.f);
|
|
|
|
audio[0][i] = input_l * gain_reduction_lin * makeup_lin;
|
|
audio[1][i] = input_r * gain_reduction_lin * makeup_lin;
|
|
}
|
|
}
|
|
|
|
private:
|
|
double samplerate;
|
|
float threshold_db = 0.f;
|
|
float attack_ms;
|
|
float release_ms;
|
|
float hp_filter;
|
|
float ratio;
|
|
float filter_frq;
|
|
float filter_exp;
|
|
float treble_boost;
|
|
|
|
sample filtered;
|
|
sample filtered_l = 0;
|
|
sample filtered_r = 0;
|
|
sample boosted_l = 0;
|
|
sample boosted_r = 0;
|
|
float attack_coef;
|
|
float release_coef;
|
|
float envelope_db = 0;
|
|
};
|
|
} // namespace trnr
|