mirror of
https://github.com/radio95-rnt/fm95.git
synced 2026-02-26 19:23:51 +01:00
74 lines
2.3 KiB
C
74 lines
2.3 KiB
C
#include "bs412.h"
|
|
|
|
#define LOG2_19000 log2f(19000.0f)
|
|
|
|
inline float dbr_to_deviation(float dbr) {
|
|
return 19000.0f * powf(2.0f, dbr * 0.332193f);
|
|
}
|
|
|
|
inline float deviation_to_dbr(float deviation) {
|
|
if (deviation < 1e-6f) return -100.0f;
|
|
return 10.0f * (log2f(deviation) - LOG2_19000) * 0.30103f;
|
|
}
|
|
|
|
void init_bs412(BS412Compressor* mpx, float mpx_deviation, float target_power, float attack, float release, float max, int sample_rate) {
|
|
mpx->mpx_deviation = mpx_deviation;
|
|
mpx->average_counter = 0;
|
|
mpx->average = 0;
|
|
mpx->sample_rate = sample_rate;
|
|
mpx->attack = expf(-1.0f / (attack * sample_rate));
|
|
mpx->release = expf(-1.0f / (release * sample_rate));
|
|
mpx->target = target_power;
|
|
mpx->gain = 1.0f;
|
|
mpx->max = max;
|
|
#ifdef BS412_DEBUG
|
|
debug_printf("Initialized MPX power measurement with sample rate: %d\n", sample_rate);
|
|
#endif
|
|
}
|
|
|
|
float bs412_compress(BS412Compressor* mpx, float sample) {
|
|
mpx->average += sample * sample * mpx->mpx_deviation * mpx->mpx_deviation;
|
|
mpx->average_counter++;
|
|
|
|
float avg_power = mpx->average / mpx->average_counter;
|
|
float avg_deviation = sqrtf(avg_power);
|
|
float modulation_power = deviation_to_dbr(avg_deviation);
|
|
|
|
#ifdef BS412_DEBUG
|
|
if(mpx->average_counter % mpx->sample_rate == 0) {
|
|
debug_printf("MPX power: %.2f dBr\n", modulation_power);
|
|
}
|
|
#endif
|
|
|
|
if (mpx->average_counter >= mpx->sample_rate * 60) {
|
|
#ifdef BS412_DEBUG
|
|
debug_printf("Resetting MPX power measurement\n");
|
|
#endif
|
|
mpx->average = avg_power;
|
|
mpx->average_counter = 1;
|
|
}
|
|
|
|
if (modulation_power > mpx->target) {
|
|
float excess_power = modulation_power - mpx->target;
|
|
|
|
if (excess_power > 0.0f && excess_power < 10.0f) {
|
|
float target_gain = dbr_to_deviation(-excess_power) / mpx->mpx_deviation;
|
|
|
|
target_gain = fmaxf(target_gain, 0.1f);
|
|
target_gain = fminf(target_gain, 1.0f);
|
|
|
|
mpx->gain = mpx->attack * mpx->gain + (1 - mpx->attack) * target_gain;
|
|
}
|
|
} else mpx->gain = fminf(1.0f, mpx->release * mpx->gain + (1 - mpx->release) * 1.0f);
|
|
|
|
mpx->gain = fminf(mpx->max, mpx->gain);
|
|
mpx->gain = fmaxf(0.0f, mpx->gain);
|
|
|
|
float output_sample = sample * mpx->gain;
|
|
float limit_dbr = mpx->target + 0.1f;
|
|
float limit_deviation_hz = dbr_to_deviation(limit_dbr);
|
|
float normalized_limit = limit_deviation_hz / mpx->mpx_deviation;
|
|
float final_limit = fminf(1.0f, normalized_limit);
|
|
|
|
return fmaxf(-final_limit, fminf(final_limit, output_sample));
|
|
} |