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You shoudn't need another stereo osclilator, because the stereo should be a harmonic, and the best way to get that is to do sin but two times the phase, same thing as in MultiSine in libfilter

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KubaPro010
2024-12-31 13:39:25 +01:00
parent 0bdf9c325b
commit 64538478e4
1 changed files with 7 additions and 11 deletions
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18
stereo_coder.c
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@@ -138,9 +138,6 @@ static void stop(int signum) {
int main() { int main() {
printf("STCode : Stereo encoder made by radio95 (with help of ChatGPT and Claude, thanks!)\n"); printf("STCode : Stereo encoder made by radio95 (with help of ChatGPT and Claude, thanks!)\n");
const float PILOT_FREQ = 19000.0f; // Don't touch this
const float STEREO_FREQ = 38000.0f; // This too
// Define formats and buffer atributes // Define formats and buffer atributes
pa_sample_spec stereo_format = { pa_sample_spec stereo_format = {
.format = PA_SAMPLE_FLOAT32NE, //Float32 NE, or Float32 Native Endian, the float in c uses the endianess of your pc, or native endian, and float is float32, and double is float64 .format = PA_SAMPLE_FLOAT32NE, //Float32 NE, or Float32 Native Endian, the float in c uses the endianess of your pc, or native endian, and float is float32, and double is float64
@@ -200,9 +197,8 @@ int main() {
return 1; return 1;
} }
Oscillator pilot_osc, stereo_osc; Oscillator pilot_osc;
init_oscillator(&pilot_osc, PILOT_FREQ, SAMPLE_RATE); init_oscillator(&pilot_osc, 19000.0, SAMPLE_RATE); // Pilot, it's there to indicate stereo and as a refrence signal with the stereo carrier
init_oscillator(&stereo_osc, STEREO_FREQ, SAMPLE_RATE);
#ifdef PREEMPHASIS #ifdef PREEMPHASIS
PreEmphasis preemp_l, preemp_r; PreEmphasis preemp_l, preemp_r;
init_pre_emphasis(&preemp_l, SAMPLE_RATE); init_pre_emphasis(&preemp_l, SAMPLE_RATE);
@@ -228,8 +224,8 @@ int main() {
uninterleave(input, left, right, BUFFER_SIZE*2); uninterleave(input, left, right, BUFFER_SIZE*2);
for (int i = 0; i < BUFFER_SIZE; i++) { for (int i = 0; i < BUFFER_SIZE; i++) {
float pilot = get_next_sample(&pilot_osc); float stereo_carrier = sinf(pilot_osc.phase*2); // Stereo carrier should be a harmonic of the pilot which is in phase, best way to generate the harmonic is to multiply the pilot's phase by two
float stereo_carrier = get_next_sample(&stereo_osc); float pilot = get_next_sample(&pilot_osc); // This is after because if it was before then the stereo would be out of phase by one increment, so [GET STEREO] ([GET PILOT] [INCREMENT PHASE])
float l_in = left[i]; float l_in = left[i];
float r_in = right[i]; float r_in = right[i];
@@ -259,12 +255,12 @@ int main() {
#endif #endif
#endif #endif
float mono = (current_left_input + current_right_input) / 2.0f; float mono = (current_left_input + current_right_input) / 2.0f; // Stereo to Mono
float stereo = (current_left_input - current_right_input) / 2.0f; float stereo = (current_left_input - current_right_input) / 2.0f; // Also Sterreo to Mono but a bit diffrent
mpx[i] = mono * MONO_VOLUME + mpx[i] = mono * MONO_VOLUME +
pilot * PILOT_VOLUME + pilot * PILOT_VOLUME +
(stereo * stereo_carrier) * STEREO_VOLUME; (stereo * stereo_carrier) * STEREO_VOLUME; // DSB-SC modulate
} }
if (pa_simple_write(output_device, mpx, sizeof(mpx), NULL) < 0) { if (pa_simple_write(output_device, mpx, sizeof(mpx), NULL) < 0) {