diff --git a/filter/bs412.c b/filter/bs412.c index 929dd6e..cc07f9a 100644 --- a/filter/bs412.c +++ b/filter/bs412.c @@ -13,83 +13,80 @@ inline float deviation_to_dbr(float deviation) { return 10*log10f((deviation*deviation)/SQRT19000); } -void init_bs412(BS412Compressor* mpx, uint32_t mpx_deviation, float target_power, float attack, float release, uint32_t sample_rate) { - mpx->mpx_deviation = mpx_deviation; - mpx->avg_power = 0.0f; - mpx->alpha = 1.0f / (BS412_TIME * sample_rate); - mpx->sample_rate = sample_rate; - mpx->attack = expf(-1.0f / (attack * sample_rate)); - mpx->release = expf(-1.0f / (release * sample_rate)); - mpx->target = deviation_to_dbr(19000.0f * pow(10.0, target_power / 10.0)); // target is expected to not be our rms format - mpx->gain = 0.0f; - mpx->can_compress = 0; - mpx->second_counter = 0; - mpx->last_output = 0.0f; +void init_bs412(BS412Compressor* comp, uint32_t mpx_deviation, float target_power, float attack, float release, uint32_t sample_rate) { + comp->mpx_deviation = mpx_deviation; + 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 = deviation_to_dbr(19000.0f * pow(10.0, target_power / 10.0)); // target is expected to not be our rms format + comp->gain = 0.0f; + comp->can_compress = 0; + comp->second_counter = 0; + comp->last_output = 0.0f; #ifdef BS412_DEBUG debug_printf("Initialized MPX power measurement with sample rate: %d\n", sample_rate); #endif } -float bs412_compress(BS412Compressor* mpx, float audio, float sample_mpx) { +float bs412_compress(BS412Compressor* comp, float audio, float sample_mpx) { float combined = audio + sample_mpx; - mpx->avg_power += mpx->alpha * ((mpx->last_output * mpx->last_output * mpx->mpx_deviation * mpx->mpx_deviation) - mpx->avg_power); + comp->avg_power += comp->alpha * ((comp->last_output * comp->last_output * comp->mpx_deviation * comp->mpx_deviation) - comp->avg_power); - float avg_deviation = sqrtf(mpx->avg_power); + float avg_deviation = sqrtf(comp->avg_power); float modulation_power = deviation_to_dbr(avg_deviation); - if(mpx->target <= -100.0f) { + if(comp->target <= -100.0f) { #ifdef BS412_DEBUG - if(mpx->sample_counter > mpx->sample_rate) { + if(comp->sample_counter > comp->sample_rate) { debug_printf("MPX power: %.2f dBr (%.1f Hz)\n", modulation_power, avg_deviation); - mpx->sample_counter = 0; + comp->sample_counter = 0; } #endif - mpx->sample_counter++; + comp->sample_counter++; return combined; } - if(mpx->sample_counter > mpx->sample_rate) { + if(comp->sample_counter > comp->sample_rate) { #ifdef BS412_DEBUG debug_printf("MPX power: %.2f dBr with gain %.2fx (%.2f dBr)\n", modulation_power, mpx->gain, deviation_to_dbr(avg_deviation * mpx->gain)); #endif - mpx->sample_counter = 0; - if(mpx->can_compress == 0) mpx->second_counter++; + comp->sample_counter = 0; + if(comp->can_compress == 0) comp->second_counter++; } - if(mpx->can_compress == 0 && mpx->second_counter > BS412_TIME) { + if(comp->can_compress == 0 && comp->second_counter > BS412_TIME) { #ifdef BS412_DEBUG debug_printf("Can compress.\n"); #endif - mpx->gain = powf(10.0f, (mpx->target - modulation_power) / 10.0f); - mpx->can_compress = 1; + comp->gain = powf(10.0f, (comp->target - modulation_power) / 10.0f); + comp->can_compress = 1; } - if(mpx->can_compress == 0) { - mpx->sample_counter++; + if(comp->can_compress == 0) { + comp->sample_counter++; return combined; } - float target_gain = powf(10.0f, (mpx->target - modulation_power) / 10.0f); - if (modulation_power > mpx->target) { - mpx->gain = mpx->attack * mpx->gain + (1.0f - mpx->attack) * target_gain; - } else { - mpx->gain = mpx->release * mpx->gain + (1.0f - mpx->release) * target_gain; - } + float target_gain = powf(10.0f, (comp->target - modulation_power) / 10.0f); + if (modulation_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; - mpx->gain = fmaxf(0.0f, fminf(2.0f, mpx->gain)); + comp->gain = fmaxf(0.0f, fminf(2.0f, comp->gain)); - float output_sample = (audio * mpx->gain) + mpx; - if(deviation_to_dbr(avg_deviation * mpx->gain) > mpx->target && deviation_to_dbr(avg_deviation) < mpx->target) { + float output_sample = (audio * comp->gain) + comp; + if(deviation_to_dbr(avg_deviation * comp->gain) > comp->target && deviation_to_dbr(avg_deviation) < comp->target) { // Gain is too much, reduce - float overshoot_dbr = deviation_to_dbr(avg_deviation * mpx->gain) - mpx->target; + float overshoot_dbr = deviation_to_dbr(avg_deviation * comp->gain) - comp->target; float reduction_factor = powf(10.0f, -overshoot_dbr / 10.0f); - mpx->gain *= reduction_factor; - mpx->gain = fmaxf(0.0f, fminf(2.0f, mpx->gain)); + comp->gain *= reduction_factor; + comp->gain = fmaxf(0.0f, fminf(2.0f, comp->gain)); } - mpx->sample_counter++; + comp->sample_counter++; - mpx->last_output = output_sample; + comp->last_output = output_sample; return output_sample; } diff --git a/filter/bs412.h b/filter/bs412.h index cd4e5ee..ebf3b5b 100644 --- a/filter/bs412.h +++ b/filter/bs412.h @@ -30,5 +30,5 @@ typedef struct // float dbr_to_deviation(float dbr); float deviation_to_dbr(float deviation); -void init_bs412(BS412Compressor *mpx, uint32_t mpx_deviation, float target_power, float attack, float release, uint32_t sample_rate); -float bs412_compress(BS412Compressor *mpx, float audio, float sample_mpx); \ No newline at end of file +void init_bs412(BS412Compressor *comp, uint32_t mpx_deviation, float target_power, float attack, float release, uint32_t sample_rate); +float bs412_compress(BS412Compressor *comp, float audio, float sample_mpx); \ No newline at end of file