mirror of
https://github.com/radio95-rnt/fm95.git
synced 2026-02-26 19:23:51 +01:00
63 lines
2.1 KiB
C
63 lines
2.1 KiB
C
#include "stereo_encoder.h"
|
|
|
|
#ifdef STEREO_SSB
|
|
static void init_delay_line(struct delay_line_t *delay_line, uint32_t sample_rate) {
|
|
delay_line->buffer = malloc(sample_rate * sizeof(float));
|
|
memset(delay_line->buffer, 0, sample_rate * sizeof(float));
|
|
}
|
|
|
|
static void set_delay_line(struct delay_line_t *delay_line, uint32_t new_delay) {
|
|
delay_line->delay = new_delay;
|
|
}
|
|
|
|
static inline float delay_line(struct delay_line_t *delay_line, float in) {
|
|
delay_line->buffer[delay_line->idx++] = in;
|
|
if (delay_line->idx >= delay_line->delay) delay_line->idx = 0;
|
|
return delay_line->buffer[delay_line->idx];
|
|
}
|
|
|
|
static void exit_delay_line(struct delay_line_t *delay_line) {
|
|
free(delay_line->buffer);
|
|
}
|
|
#endif
|
|
|
|
// Multiplier is the multiplier to get to 19 khz
|
|
void init_stereo_encoder(StereoEncoder* st, uint8_t multiplier, Oscillator* osc, float audio_volume, float pilot_volume) {
|
|
st->multiplier = multiplier;
|
|
st->osc = osc;
|
|
st->pilot_volume = pilot_volume;
|
|
st->audio_volume = audio_volume;
|
|
#ifdef STEREO_SSB
|
|
init_delay_line(&st->delay, 15); // 7*2+1
|
|
#endif
|
|
}
|
|
|
|
#ifdef STEREO_SSB
|
|
float stereo_encode(StereoEncoder* st, uint8_t enabled, float left, float right, firhilbf *hilbert) {
|
|
#else
|
|
float stereo_encode(StereoEncoder* st, uint8_t enabled, float left, float right) {
|
|
#endif
|
|
float mid = (left+right) * 0.5f;
|
|
if(!enabled) return mid * st->audio_volume;
|
|
mid = delay_line(&st->delay, mid);
|
|
|
|
float half_audio = st->audio_volume * 0.5f;
|
|
|
|
float side = (left-right) * 0.5f;
|
|
|
|
#ifdef STEREO_SSB
|
|
float complex stereo_hilbert;
|
|
firhilbf_r2c_execute(*hilbert, side, &stereo_hilbert);
|
|
float signalx2cos = get_oscillator_cos_multiplier_ni(st->osc, st->multiplier * 2.0f);
|
|
#endif
|
|
|
|
float signalx1 = get_oscillator_sin_multiplier_ni(st->osc, st->multiplier);
|
|
float signalx2 = get_oscillator_sin_multiplier_ni(st->osc, st->multiplier * 2.0f);
|
|
|
|
#ifdef STEREO_SSB
|
|
float stereo = (crealf(stereo_hilbert) * signalx2cos) - (cimagf(stereo_hilbert) * signalx2);
|
|
return (mid*half_audio) + (signalx1*st->pilot_volume) + (stereo * half_audio);
|
|
#else
|
|
return (mid*half_audio) + (signalx1*st->pilot_volume) + ((side*signalx2) * half_audio);
|
|
#endif
|
|
} |