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Code Issues Activity

bs412 gating and also fix it

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This commit is contained in:
kuba
2026-05-04 13:28:30 +02:00
parent fafc201fb4
commit 6f929f0c18
3 changed files with 51 additions and 47 deletions
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filter/bs412.c
+30 -24
View File
@@ -1,43 +1,54 @@
#include "bs412.h"
#define BS412_TIME 60
#define ENABLE_TIME 50
#define ENABLE_TIME 45
#define CLAMP(x, lo, hi) (((x) < (lo)) ? (lo) : ((x) > (hi) ? (hi) : (x)))
inline float dbr_to_deviation(float dbr) {
return 19000.0f * sqrtf(pow(10.0, dbr / 10.0));
}
#define REF_POWER (19000.0f * 19000.0f) // 361,000,000
inline float power_to_dbr(float power) {
inline float power_to_dbr(float power, float ref) {
if (power < 1e-12f) return -100.0f;
return 10*log10f(power / REF_POWER);
return 10*log10f(power / ref);
}
void init_bs412(BS412Compressor* comp, uint32_t mpx_deviation, float target_power, float attack, float release, float max_gain, uint32_t sample_rate) {
comp->mpx_deviation = mpx_deviation;
void init_bs412(BS412Compressor* comp, uint32_t mpx_deviation, float target_power, float attack, float release, float max_gain, float gate, uint32_t sample_rate) {
comp->reference = (19000.0f / mpx_deviation) * (19000.0f / mpx_deviation); // 0 dbr is a signal which generates a deviation of 19 khz
comp->avg_power = 0.0f;
comp->alpha = 1.0f / (BS412_TIME * sample_rate);
comp->sample_rate = sample_rate;
comp->attack = expf(-1.0f / (attack * sample_rate));
comp->release = expf(-1.0f / (release * sample_rate));
comp->target = dbr_to_deviation(target_power) * dbr_to_deviation(target_power);
comp->target = comp->reference * powf(10.0f, target_power / 10.0f);;
comp->gain = 1.0f;
comp->can_compress = 0;
comp->second_counter = 0;
comp->max_gain = max_gain;
comp->gate_threshold = comp->reference * powf(10.0f, gate / 10.0f);
comp->init = true;
#ifdef BS412_DEBUG
debug_printf("Initialized MPX power measurement with sample rate: %d\n", sample_rate);
#endif
}
void reinit_bs412(BS412Compressor* comp, uint32_t mpx_deviation, float target_power, float attack, float release, float max_gain, float gate) {
comp->reference = (19000.0f / mpx_deviation) * (19000.0f / mpx_deviation); // 0 dbr is a signal which generates a deviation of 19 khz
comp->target = comp->reference * powf(10.0f, target_power / 10.0f);;
comp->gate_threshold = comp->reference * powf(10.0f, gate / 10.0f);
comp->attack = expf(-1.0f / (attack * sample_rate));
comp->release = expf(-1.0f / (release * sample_rate));
comp->max_gain = max_gain;
}
float bs412_compress(BS412Compressor* comp, float audio, float sample_mpx, float* mpx_power) {
float combined = audio + sample_mpx;
float output_sample = (audio * comp->gain) + sample_mpx;
comp->avg_power += comp->alpha * ((output_sample * output_sample * comp->mpx_deviation * comp->mpx_deviation) - comp->avg_power);
float inst_power = output_sample * output_sample;
float audio_power = (audio * comp->gain) * (audio * comp->gain);
if(comp->sample_counter > comp->sample_rate) {
float w = (audio_power - comp->gate_threshold) / comp->gate_threshold;
w = CLAMP(w, 0.0f, 1.0f);
comp->avg_power += comp->alpha * w * (inst_power - comp->avg_power);
if(comp->sample_counter >= comp->sample_rate) {
comp->sample_counter = 0;
if(comp->can_compress == 0) comp->second_counter++;
}
@@ -52,21 +63,16 @@ float bs412_compress(BS412Compressor* comp, float audio, float sample_mpx, float
float safe_power = fmaxf(comp->avg_power, 1e-12f);
float target_gain = sqrtf(comp->target / safe_power);
if (comp->avg_power > comp->target) comp->gain = comp->attack * comp->gain + (1.0f - comp->attack) * target_gain;
else comp->gain = comp->release * comp->gain + (1.0f - comp->release) * target_gain;
if (comp->avg_power > comp->target)
comp->gain = comp->attack * comp->gain + (1.0f - comp->attack) * target_gain;
else
comp->gain = comp->release * comp->gain + (1.0f - comp->release) * target_gain;
comp->gain = CLAMP(comp->gain, 0.0f, comp->max_gain);
float power_after_gain = comp->avg_power * comp->gain * comp->gain;
if(power_after_gain > comp->target && comp->avg_power < comp->target) {
float reduction = sqrtf(comp->target / power_after_gain);
comp->gain = CLAMP(comp->gain * reduction, 0.01f, comp->max_gain);
}
comp->gain = CLAMP(comp->gain, 0.01f, comp->max_gain);
comp->sample_counter++;
if(mpx_power != NULL) *mpx_power = power_to_dbr(comp->avg_power);
if(mpx_power != NULL) *mpx_power = power_to_dbr(comp->avg_power, comp->reference);
if(comp->can_compress) return output_sample;
return combined;
filter/bs412.h
+6 -4
View File
@@ -11,9 +11,8 @@
#include "../lib/debug.h"
#endif
typedef struct
{
uint32_t mpx_deviation;
typedef struct {
float reference;
uint32_t sample_rate;
uint32_t sample_counter;
float target;
@@ -26,7 +25,10 @@ typedef struct
uint8_t can_compress : 1;
uint8_t second_counter;
float last_output;
float gate_threshold;
bool init;
} BS412Compressor;
void init_bs412(BS412Compressor *comp, uint32_t mpx_deviation, float target_power, float attack, float release, float max_gain, uint32_t sample_rate);
void init_bs412(BS412Compressor *comp, uint32_t mpx_deviation, float target_power, float attack, float release, float max_gain, float gate, uint32_t sample_rate);
void reinit_bs412(BS412Compressor *comp, uint32_t mpx_deviation, float target_power, float attack, float release, float max_gain, float gate);
float bs412_compress(BS412Compressor *comp, float audio, float sample_mpx, float* mpx_power);