radio95/fm95
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kuba
2025-04-27 13:11:42 +02:00
parent ca82168784
commit c4d5c39ed5
17 changed files with 82 additions and 149 deletions
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dsp/gain_control.c
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#include "gain_control.h"
void initAGC(AGC* agc, int sampleRate, float targetLevel, float minGain, float maxGain, float attackTime, float releaseTime) {
agc->sampleRate = sampleRate;
agc->targetLevel = targetLevel;
agc->minGain = minGain;
agc->maxGain = maxGain;
agc->attackTime = attackTime;
agc->releaseTime = releaseTime;
agc->attackCoef = expf(-1.0f / (sampleRate * attackTime));
agc->releaseCoef = expf(-1.0f / (sampleRate * releaseTime));
agc->currentGain = 1.0f;
agc->currentLevel = 0.0f;
agc->rms_buffer = 0.0f;
}
float process_agc_stereo(AGC* agc, float left, float right, float *right_out) {
float sample = (left+right)/2;
float x2 = sample * sample;
float rmsAlpha = expf(-1.0f / (agc->sampleRate * 0.04));
agc->rms_buffer = rmsAlpha * agc->rms_buffer + (1.0f - rmsAlpha) * x2;
float instantLevel = sqrtf(agc->rms_buffer);
float alpha = (instantLevel > agc->currentLevel) ? agc->attackCoef : agc->releaseCoef;
agc->currentLevel = alpha * agc->currentLevel + (1.0f - alpha) * instantLevel;
float desiredGain = agc->targetLevel / fmaxf(agc->currentLevel, 1e-10f);
desiredGain = fminf(fmaxf(desiredGain, agc->minGain), agc->maxGain);
float gainAlpha = (desiredGain > agc->currentGain) ? agc->attackCoef : agc->releaseCoef;
agc->currentGain = gainAlpha * agc->currentGain + (1.0f - gainAlpha) * desiredGain;
*right_out = right * agc->currentGain;
return left * agc->currentGain;
}