turn on and off mpx generation (carrier wave only)

src/pifmrds/control_pipe.c

@@ -193,6 +193,12 @@ ResultAndArg poll_control_pipe() {
 			printf("\n");
 			resarg.res = CONTROL_PIPE_PILVOL_SET;
 			resarg.arg = arg;
+		} else if(fifo[0] == 'M' && fifo[1] == 'P' && fifo[2] == 'X') {
+			int mpx = ( strcmp(arg, "ON") == 0 );
+			printf("Set Generate MPX to ");
+			if(mpx) printf("ON\n"); else printf("OFF\n");
+			resarg.res = CONTROL_PIPE_MPXGEN_SET;
+			resarg.arg_int = mpx;
 		}
 	}
 	return resarg;

src/pifmrds/control_pipe.h

@@ -24,6 +24,7 @@
 #define CONTROL_PIPE_RDSVOL_SET 17
 #define CONTROL_PIPE_PAUSE_SET 18
 #define CONTROL_PIPE_PILVOL_SET 19 //fitting
+#define CONTROL_PIPE_MPXGEN_SET 20
 
 typedef struct {
     int res;

src/pifmrds/fm_mpx.c

@@ -200,9 +200,9 @@ int fm_mpx_open(char *filename, size_t len, int raw, double preemphasis, int raw
 
 // samples provided by this function are in 0..10: they need to be divided by
 // 10 after.
-int fm_mpx_get_samples(float *mpx_buffer, int drds, float compressor_decay, float compressor_attack, float compressor_max_gain_recip, int disablestereo, float gain, int enablecompressor, int rds_ct_enabled, float rds_volume, int paused, float pilot_volume) {
+int fm_mpx_get_samples(float *mpx_buffer, int drds, float compressor_decay, float compressor_attack, float compressor_max_gain_recip, int disablestereo, float gain, int enablecompressor, int rds_ct_enabled, float rds_volume, int paused, float pilot_volume, int generate_multiplex) {
     int stereo_capable = (channels > 1) && (!disablestereo); //chatgpt
-    if(!drds) get_rds_samples(mpx_buffer, length, stereo_capable, rds_ct_enabled, rds_volume);
+    if(!drds && generate_multiplex) get_rds_samples(mpx_buffer, length, stereo_capable, rds_ct_enabled, rds_volume);
 
     if(inf == NULL) return 0; // if there is no audio, stop here
     
@@ -326,6 +326,7 @@ int fm_mpx_get_samples(float *mpx_buffer, int drds, float compressor_decay, floa
         // Generate the stereo mpx
         if( channels > 1 ) {
             if(!disablestereo) {
+                if(generate_multiplex) {
                     if(1) {
                         mpx_buffer[i] +=  4.05*(out_left+out_right) + // Stereo sum signal
                             4.05 * carrier_38[phase_38] * (out_left-out_right) + // Stereo difference signal
@@ -343,18 +344,23 @@ int fm_mpx_get_samples(float *mpx_buffer, int drds, float compressor_decay, floa
                         phase_3125++;
                         if(phase_3125 >= 6) phase_3125 = 0;
                     }
+                }
             } else {
+                if(generate_multiplex) {
                     mpx_buffer[i] =  
                         mpx_buffer[i] +
                         4.05*(out_left+out_right);      // Unmodulated L+R signal
                 }
             }
+        }
         else
         {
+            if(generate_multiplex) {
                 mpx_buffer[i] =  
                     mpx_buffer[i] +
                     4.05*out_left;      // Unmodulated monophonic signal
             }
+        } 
             
         audio_pos++;   
         

src/pifmrds/fm_mpx.h

@@ -22,5 +22,5 @@
 */
 
 extern int fm_mpx_open(char *filename, size_t len, int raw, double preemphasis, int rawSampleRate, int rawChannels, float cutoff_freq);
-extern int fm_mpx_get_samples(float *mpx_buffer, int drds, float compressor_decay, float compressor_attack, float compressor_max_gain_recip, int disablestereo, float gain, int enablecompressor, int rds_ct_enabled, float rds_volume, int paused, float pilot_volume);
+extern int fm_mpx_get_samples(float *mpx_buffer, int drds, float compressor_decay, float compressor_attack, float compressor_max_gain_recip, int disablestereo, float gain, int enablecompressor, int rds_ct_enabled, float rds_volume, int paused, float pilot_volume, int generate_multiplex);
 extern int fm_mpx_close();

src/pifmrds/pi_fm_rds.cpp

@@ -44,7 +44,7 @@ fatal(char *fmt, ...)
     terminate(0);
 }
 
-int tx(uint32_t carrier_freq, char *audio_file, uint16_t pi, char *ps, char *rt, char *control_pipe, int pty, int *af_array, int raw, int drds, double preemp, int power, int rawSampleRate, int rawChannels, int deviation, int ta, int tp, float cutoff_freq, float gaim, float compressor_decay, float compressor_attack, float compressor_max_gain_recip, int enablecompressor, int rds_ct_enabled, float rds_volume, float pilot_volume) {
+int tx(uint32_t carrier_freq, char *audio_file, uint16_t pi, char *ps, char *rt, char *control_pipe, int pty, int *af_array, int raw, int drds, double preemp, int power, int rawSampleRate, int rawChannels, int deviation, int ta, int tp, float cutoff_freq, float gaim, float compressor_decay, float compressor_attack, float compressor_max_gain_recip, int enablecompressor, int rds_ct_enabled, float rds_volume, float pilot_volume, int disablestereo) {
     // Catch all signals possible - it is vital we kill the DMA engine
     // on process exit!
     // for (int i = 0; i < 64; i++) {
@@ -72,7 +72,7 @@ int tx(uint32_t carrier_freq, char *audio_file, uint16_t pi, char *ps, char *rt,
     int data_len = 0;
     int data_index = 0;
 
-    int disablestereo = 0;
+    int generate_multiplex = 1;
 
     //set the power
     padgpio gpiopad;
@@ -187,10 +187,12 @@ int tx(uint32_t carrier_freq, char *audio_file, uint16_t pi, char *ps, char *rt,
                 paused = pollResult.arg_int;
             } else if(pollResult.res == CONTROL_PIPE_PILVOL_SET) {
                 pilot_volume = std::stof(pollResult.arg);
+            } else if(pollResult.res == CONTROL_PIPE_MPXGEN_SET) {
+                generate_multiplex = pollResult.arg_int;
             }
         }
 
-			if( fm_mpx_get_samples(data, drds, compressor_decay, compressor_attack, compressor_max_gain_recip, disablestereo, gaim, enablecompressor, rds_ct_enabled, rds_volume, paused, pilot_volume) < 0 ) {
+			if( fm_mpx_get_samples(data, drds, compressor_decay, compressor_attack, compressor_max_gain_recip, disablestereo, gaim, enablecompressor, rds_ct_enabled, rds_volume, paused, pilot_volume, generate_multiplex) < 0 ) {
                     terminate(0);
                 }
                 data_len = DATA_SIZE;
@@ -377,6 +379,6 @@ int main(int argc, char **argv) {
     int FifoSize=DATA_SIZE*2;
     //fmmod=new ngfmdmasync(carrier_freq,228000,14,FifoSize, false, gpiopin); //you can mod
     fmmod=new ngfmdmasync(carrier_freq,228000,14,FifoSize, false);
-    int errcode = tx(carrier_freq, audio_file, pi, ps, rt, control_pipe, pty, alternative_freq, raw, drds, preemp, power, rawSampleRate, rawChannels, deviation, ta, tp, cutofffreq, gain, compressor_decay, compressor_attack, compressor_max_gain_recip, enable_compressor, ct, rds_volume, pilot_volume);
+    int errcode = tx(carrier_freq, audio_file, pi, ps, rt, control_pipe, pty, alternative_freq, raw, drds, preemp, power, rawSampleRate, rawChannels, deviation, ta, tp, cutofffreq, gain, compressor_decay, compressor_attack, compressor_max_gain_recip, enable_compressor, ct, rds_volume, pilot_volume, 0);
     terminate(errcode);
 }