From 0782a647106f74beb7847230ab3c78450601db1d Mon Sep 17 00:00:00 2001
From: KubaPro010 <kuba.pro010@gmail.com>
Date: Tue, 28 Apr 2026 19:56:13 +0200
Subject: [PATCH] fixes

---
 filter/bs412.c | 48 +++++++++++++++++++++---------------------------
 filter/bs412.h |  2 --
 2 files changed, 21 insertions(+), 29 deletions(-)

diff --git a/filter/bs412.c b/filter/bs412.c
index ada0af2..a0ca48c 100644
--- a/filter/bs412.c
+++ b/filter/bs412.c
@@ -1,19 +1,19 @@
 #include "bs412.h"
 
 #define BS412_TIME 60
+#define ENABLE_TIME 50
 #define CLAMP(x, lo, hi) (((x) < (lo)) ? (lo) : ((x) > (hi) ? (hi) : (x)))
 
-#define SQRT19000 180499999.99999997f // (19000 / sqrt(2)) * 19000 / sqrt(2)
-
-// inline float dbr_to_deviation(float dbr) {
-// 	return 19000.0f * sqrtf(pow(10.0, dbr / 10.0));
-// }
-
-inline float deviation_to_dbr(float deviation) {
-	if (deviation < 1e-6f) return -100.0f;
-	return 10*log10f((deviation*deviation)/SQRT19000);
+inline float dbr_to_deviation(float dbr) {
+	return 19000.0f * sqrtf(pow(10.0, dbr / 10.0));
 }
 
+// #define SQRT19000 180499999.99999997f // (19000 / sqrt(2)) * 19000 / sqrt(2)
+// inline float deviation_to_dbr(float deviation) {
+// 	if (deviation < 1e-6f) return -100.0f;
+// 	return 10*log10f((deviation*deviation)/SQRT19000);
+// }
+
 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;
 	comp->avg_power = 0.0f;
@@ -21,7 +21,7 @@ void init_bs412(BS412Compressor* comp, uint32_t mpx_deviation, float target_powe
 	comp->sample_rate = sample_rate;
 	comp->attack = expf(-1.0f / (attack * sample_rate));
 	comp->release = expf(-1.0f / (release * sample_rate));
-	comp->target = target_power; // target is expected to not be our rms format
+	comp->target = dbr_to_deviation(target_power) * dbr_to_deviation(target_power);
 	comp->gain = 1.0f;
 	comp->can_compress = 0;
 	comp->second_counter = 0;
@@ -37,41 +37,35 @@ float bs412_compress(BS412Compressor* comp, float audio, float sample_mpx) {
 
 	comp->avg_power += comp->alpha * ((output_sample * output_sample * comp->mpx_deviation * comp->mpx_deviation) - comp->avg_power);
 
-	if(comp->sample_counter % 8 == 0) {
-		comp->avg_deviation = sqrtf(comp->avg_power);
-		comp->modulation_power = deviation_to_dbr(comp->avg_deviation);
-	}
-
 	if(comp->sample_counter > comp->sample_rate) {
 		comp->sample_counter = 0;
 		if(comp->can_compress == 0) comp->second_counter++;
 	}
 
-	if(comp->can_compress == 0 && comp->second_counter > BS412_TIME) {
+	if(comp->can_compress == 0 && comp->second_counter > ENABLE_TIME) {
 		#ifdef BS412_DEBUG
 		debug_printf("Can compress.\n");
 		#endif
 		comp->can_compress = 1;
 		comp->second_counter = 0;
-	} else {
-		comp->sample_counter++;
-		return combined;
 	}
 
-	float target_gain = expf((comp->target - comp->modulation_power) * 0.2302585093f); // 1/10 * ln(10)
-	if (comp->modulation_power > comp->target) comp->gain = comp->attack * comp->gain + (1.0f - comp->attack) * target_gain;
+	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;
 	
 	comp->gain = CLAMP(comp->gain, 0.0f, comp->max_gain);
 
-	float dev_after_gain = deviation_to_dbr(comp->avg_deviation * comp->gain);
-	if(dev_after_gain > comp->target && comp->modulation_power < comp->target) {
-		// Gain is too much, reduce
-		float reduction_factor = expf((comp->target - dev_after_gain) * 0.2302585093f);
-		comp->gain = CLAMP(comp->gain * reduction_factor, 0.01f, 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->sample_counter++;
 
-	return output_sample;
+	if(comp->can_compress) return output_sample;
+	return combined;
 }
diff --git a/filter/bs412.h b/filter/bs412.h
index 3d79e4d..ad403d1 100644
--- a/filter/bs412.h
+++ b/filter/bs412.h
@@ -26,8 +26,6 @@ typedef struct
 	uint8_t can_compress : 1;
 	uint8_t second_counter;
 	float last_output;
-	float avg_deviation;
-	float modulation_power;
 } BS412Compressor;
 
 // float dbr_to_deviation(float dbr);