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clean up the stereo mpx code

This commit is contained in:
Kuba 2025-02-22 08:37:21 +00:00
parent d8cd1b34cf
commit c08790ee3b
1 changed files with 22 additions and 35 deletions
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57
src/pifmrds/fm_mpx.c
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@ -35,7 +35,6 @@
#define PI 3.14159265359 #define PI 3.14159265359
#define FIR_PHASES (32) #define FIR_PHASES (32)
#define FIR_TAPS (32) // MUST be a power of 2 for the circular buffer #define FIR_TAPS (32) // MUST be a power of 2 for the circular buffer
@ -54,7 +53,6 @@ int phase_38 = 0;
int phase_3125 = 0; int phase_3125 = 0;
int phase_19 = 0; int phase_19 = 0;
float downsample_factor; float downsample_factor;
int raw_; int raw_;
@ -68,7 +66,7 @@ float fir_buffer_left[FIR_TAPS] = {0};
float fir_buffer_right[FIR_TAPS] = {0}; float fir_buffer_right[FIR_TAPS] = {0};
int fir_index = 0; int fir_index = 0;
int channels; int channels;
float left_max=1, right_max=1; // start compressor with low gain float left_max=0, right_max=0; // start compressor with low gain
SNDFILE *inf; SNDFILE *inf;
@ -334,55 +332,44 @@ int fm_mpx_get_samples(float *mpx_buffer, fm_mpx_data *data) {
if(data->enablecompressor) out_right=out_right/(right_max+data->compressor_max_gain_recip); // Adjust volume with limited maximum gain if(data->enablecompressor) out_right=out_right/(right_max+data->compressor_max_gain_recip); // Adjust volume with limited maximum gain
} }
if(data->enablecompressor) out_left= out_left/(left_max+data->compressor_max_gain_recip); // Adjust volume with limited maximum gain if(data->enablecompressor) out_left= out_left/(left_max+data->compressor_max_gain_recip); // Adjust volume with limited maximum gain
if(data->drds) mpx_buffer[i] = 0.0; if(data->drds) mpx_buffer[i] = 0.0; // before this, there is just rds here, so we can set it to 0
if(data->paused) { if(data->paused) {
out_left = 0; out_left = 0;
if(channels > 1) out_right = 0; if(channels > 1) out_right = 0;
} }
out_left = limiter(out_left, data->limiter_threshold, 1); out_left = limiter(out_left, data->limiter_threshold, 1);
if( channels > 1 ) out_right = limiter(out_right, data->limiter_threshold, 1); if( channels==2) out_right = limiter(out_right, data->limiter_threshold, 1);
out_left = clip(out_left, 1); //max is gonna be 1.0 (0 db), lowest is -1.0 (-inf db) out_left = clip(out_left, 1); //max is gonna be 1.0 (0 db), lowest is -1.0 (-inf db)
if(channels>1) out_right = clip(out_right, 1); if(channels==2) out_right = clip(out_right, 1);
// Generate the stereo mpx // Generate the stereo mpx
if( channels > 1 ) { if(channels == 2 && !data->disablestereo) {
if(!data->disablestereo) { if(1) {
if(generate_multiplex) { // 4.5 and 0.9 are the volumes, thats because we dont have 75000 khz of deviation, instead we have 7500 khz, so that needs to be louder by 10 times than normal
if(1) { mpx_buffer[i] += 4.5*(out_left+out_right) + // Stereo sum signal
// 4.5 and 0.9 are the volumes, thats because we dont have 75000 khz of deviation, instead we have 7500 khz, so that needs to be louder by 10 times than normal 4.5 * carrier_38[phase_38] * (out_left-out_right) + // Stereo difference signal
mpx_buffer[i] += 4.5*(out_left+out_right) + // Stereo sum signal 0.9*carrier_19[phase_19]; // Stereo pilot tone
4.5 * carrier_38[phase_38] * (out_left-out_right) + // Stereo difference signal phase_19++;
0.9*carrier_19[phase_19]; // Stereo pilot tone phase_38++;
phase_19++; if(phase_19 >= 12) phase_19 = 0;
phase_38++; if(phase_38 >= 6) phase_38 = 0;
if(phase_19 >= 12) phase_19 = 0; } else { // polar stereo (https://forums.stereotool.com/viewtopic.php?t=6233, https://personal.utdallas.edu/~dlm/3350%20comm%20sys/ITU%20std%20on%20FM%20--%20R-REC-BS.450-3-200111-I!!PDF-E.pdf)
if(phase_38 >= 6) phase_38 = 0; mpx_buffer[i] += 4.5*(out_left+out_right) + // Stereo sum signal (L+R)
} else { // polar stereo (https://forums.stereotool.com/viewtopic.php?t=6233, https://personal.utdallas.edu/~dlm/3350%20comm%20sys/ITU%20std%20on%20FM%20--%20R-REC-BS.450-3-200111-I!!PDF-E.pdf) 4.5 * carrier_3125[phase_3125] * (out_left-out_right); // Stereo difference signal
mpx_buffer[i] += 4.5*(out_left+out_right) + // Stereo sum signal (L+R) phase_3125++;
4.5 * carrier_3125[phase_3125] * (out_left-out_right); // Stereo difference signal if(phase_3125 >= 8) phase_3125 = 0;
phase_3125++;
if(phase_3125 >= 8) phase_3125 = 0;
}
}
} else {
if(generate_multiplex) {
mpx_buffer[i] =
mpx_buffer[i] +
4.5*(out_left+out_right); // Unmodulated L+R signal
}
} }
} } else if(channels == 1 || data->disablestereo)
else
{ {
if(generate_multiplex) { if(data->generate_multiplex) {
mpx_buffer[i] = mpx_buffer[i] =
mpx_buffer[i] + mpx_buffer[i] +
4.5*out_left; // Unmodulated monophonic signal 4.5*out_left; // Unmodulated monophonic signal
} }
} }
if(!generate_multiplex) { if(!data->generate_multiplex) {
mpx_buffer[i] = mpx_buffer[i] =
0.0; 0.0;
} }