radio95/fm95
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Code Issues Activity

speed up agc (in performance, not audio levels)

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KubaPro010
2025-06-08 10:21:13 +02:00
parent 256f91fbdf
commit 178b42386a
4 changed files with 13 additions and 11 deletions
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3
.vscode/settings.json vendored
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@@ -32,7 +32,8 @@
"string": "c",
"string_view": "c",
"version.h": "c",
"cdecl.h": "c"
"cdecl.h": "c",
"algorithm": "c"
},
"C_Cpp.errorSquiggles": "disabled"
}

9
dsp/gain_control.c
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@@ -17,10 +17,8 @@ void initAGC(AGC* agc, int sampleRate, float targetLevel, float minGain, float m
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 process_agc(AGC* agc, float sidechain) {
float x2 = sidechain * sidechain;
float rmsAlpha = expf(-1.0f / (agc->sampleRate * 0.04));
agc->rms_buffer = rmsAlpha * agc->rms_buffer + (1.0f - rmsAlpha) * x2;
@@ -35,6 +33,5 @@ float process_agc_stereo(AGC* agc, float left, float right, float *right_out) {
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;
return agc->currentGain;
}

2
dsp/gain_control.h
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@@ -19,4 +19,4 @@ typedef struct {
} AGC;
void initAGC(AGC* agc, int sampleRate, float targetLevel, float minGain, float maxGain, float attackTime, float releaseTime);
float process_agc_stereo(AGC* agc, float left, float right, float *right_out);
float process_agc(AGC* agc, float sidechain);

10
src/fm95.c
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@@ -477,12 +477,16 @@ int main(int argc, char **argv) {
float ready_r = apply_preemphasis(&preemp_r, right[i]);
iirfilt_rrrf_execute(lpf_l, ready_l, &ready_l);
iirfilt_rrrf_execute(lpf_r, ready_r, &ready_r);
ready_l = process_agc_stereo(&agc, ready_l, ready_r, &ready_r);
float agc_gain = process_agc(&agc, ((ready_l + ready_r) * 0.5f));
ready_l *= agc_gain;
ready_r *= agc_gain;
ready_l = hard_clip(ready_l*audio_volume, clipper_threshold);
ready_r = hard_clip(ready_r*audio_volume, clipper_threshold);
float mid = (ready_l + ready_r) / 2.0f;
float side = (ready_l - ready_r) / 2.0f;
float mid = (ready_l + ready_r) * 0.5f;
float side = (ready_l - ready_r) * 0.5f;
audio = mid*MONO_VOLUME;
if(stereo) {