pifmrds reads from stdin

./pifmrds now can read raw data from stdin
use option -raw

examples:
sudo ./pifmrds -freq 102.0 -audio - < <(while true; do cat src/pifmrds/stereo_44100.wav; done)
sudo ./pifmrds -raw -freq 102.0 -audio - < <(while true; do cat src/pifmrds/stereo_44100.wav; done)

based on this pull request: ChristopheJacquet/PiFmRds#23

src/pifmrds/fm_mpx.c

@@ -80,12 +80,18 @@ float *alloc_empty_buffer(size_t length) {
 }
 
 
-int fm_mpx_open(char *filename, size_t len) {
+int fm_mpx_open(char *filename, size_t len, int raw) {
     length = len;
 
     if(filename != NULL) {
         // Open the input file
         SF_INFO sfinfo;
+
+        if(raw) {
+            sfinfo.format = SF_FORMAT_RAW | SF_FORMAT_PCM_16;
+            sfinfo.samplerate = 44100;
+            sfinfo.channels = 2;
+        }
 
         // stdin or file on the filesystem?
         if(filename[0] == '-') {
@@ -118,7 +124,7 @@ int fm_mpx_open(char *filename, size_t len) {
 
         // Choose a cutoff frequency for the low-pass FIR filter
         float cutoff_freq = 15700;
-		//float cutoff_freq = 3000; //For NBFM
+        //float cutoff_freq = 3000; //For NBFM
         if(in_samplerate/2 < cutoff_freq) cutoff_freq = in_samplerate/2 * .8;
 
 
@@ -205,7 +211,7 @@ int fm_mpx_get_samples(float *mpx_buffer) {
                     if(audio_len == 0) {
                         if( sf_seek(inf, 0, SEEK_SET) < 0 ) {
                             fprintf(stderr, "Could not rewind in audio file, terminating\n");
-                            return -1;
+							return -1;
                         }
                     } else {
                         break;
@@ -234,10 +240,10 @@ int fm_mpx_get_samples(float *mpx_buffer) {
         int iphase =  ((int) (audio_pos*FIR_PHASES/downsample_factor) );// I think this is correct
         //int iphase=FIR_PHASES-1;  // test override
         //printf("%d %d \n",fir_index,iphase); // diagnostics
-	// Sanity checks
+    // Sanity checks
         if ( iphase < 0 ) {iphase=0; printf("low\n"); }// Seems to run faster with these checks in place
         if ( iphase >= FIR_PHASES ) {iphase=FIR_PHASES-2; printf("high\n"); }
-		
+        
         if( channels > 1 )
         {
           for(int fi=0; fi<FIR_TAPS; fi++)  // fi = Filter Index
@@ -253,7 +259,7 @@ int fm_mpx_get_samples(float *mpx_buffer) {
             out_left+=low_pass_fir[iphase][fi] * fir_buffer_left[(fir_index-fi)&(FIR_TAPS-1)];
           }
         }
-		
+        
         // Simple broadcast compressor
         // 
         // The goal is to get the loudest sounding audio while 

src/pifmrds/fm_mpx.h

@@ -21,6 +21,6 @@
     along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-extern int fm_mpx_open(char *filename, size_t len);
+extern int fm_mpx_open(char *filename, size_t len, int raw);
 extern int fm_mpx_get_samples(float *mpx_buffer);
 extern int fm_mpx_close();

src/pifmrds/pi_fm_rds.cpp

@@ -129,7 +129,6 @@ terminate(int num)
     fm_mpx_close();
     close_control_pipe();
 
-
     exit(num);
 }
 
@@ -151,7 +150,7 @@ fatal(char *fmt, ...)
 #define DATA_SIZE 5000
 
 
-int tx(uint32_t carrier_freq, char *audio_file, uint16_t pi, char *ps, char *rt, float ppm, char *control_pipe) {
+int tx(uint32_t carrier_freq, char *audio_file, uint16_t pi, char *ps, char *rt, float ppm, char *control_pipe, int raw) {
     // Catch all signals possible - it is vital we kill the DMA engine
     // on process exit!
     for (int i = 0; i < 64; i++) {
@@ -171,7 +170,7 @@ int tx(uint32_t carrier_freq, char *audio_file, uint16_t pi, char *ps, char *rt,
     int data_index = 0;
 
     // Initialize the baseband generator
-    if(fm_mpx_open(audio_file, DATA_SIZE) < 0) return 1;
+    if(fm_mpx_open(audio_file, DATA_SIZE, raw) < 0) return 1;
 
     // Initialize the RDS modulator
     char myps[9] = {0};
@@ -232,18 +231,20 @@ int tx(uint32_t carrier_freq, char *audio_file, uint16_t pi, char *ps, char *rt,
             varying_ps = 0;
         }
 
-			if( fm_mpx_get_samples(data) < 0 ) {
-                    terminate(0);
-                }
-                data_len = DATA_SIZE;
-				for(int i=0;i< data_len;i++)
+		if( fm_mpx_get_samples(data) < 0 ) {
+			//terminate(0);
+			return 0;
+		} else {
+			data_len = DATA_SIZE;
+			for(int i=0;i< data_len;i++)
 			{
 
-            	devfreq[i] = data[i]*deviation_scale_factor;
+				devfreq[i] = data[i]*deviation_scale_factor;
 
 
-            }	
+			}	
 			fmmod->SetFrequencySamples(devfreq,data_len);
+		}
 	}    
 
     return 0;
@@ -259,6 +260,7 @@ int main(int argc, char **argv) {
     uint16_t pi = 0x1234;
 
     float ppm = 0;
+	int raw = 0;
 
 
     // Parse command-line arguments
@@ -291,16 +293,18 @@ int main(int argc, char **argv) {
         } else if(strcmp("-ctl", arg)==0 && param != NULL) {
             i++;
             control_pipe = param;
+        } else if(strcmp("-raw", arg)==0) { //expect raw input of 44.1khz, 2 channels, 16 bit pcm.
+            raw = 1;
         } 
         else {
             fatal("Unrecognised argument: %s.\n"
             "Syntax: pi_fm_rds [-freq freq] [-audio file] [-ppm ppm_error] [-pi pi_code]\n"
-            "                  [-ps ps_text] [-rt rt_text] [-ctl control_pipe]\n", arg);
+            "                  [-ps ps_text] [-rt rt_text] [-ctl control_pipe] [-raw]\n", arg);
         }
     }
 	int FifoSize=DATA_SIZE*2;
     fmmod=new ngfmdmasync(carrier_freq,228000,14,FifoSize);
-    int errcode = tx(carrier_freq,  audio_file, pi, ps, rt, ppm, control_pipe);
+    int errcode = tx(carrier_freq,  audio_file, pi, ps, rt, ppm, control_pipe, raw);
 
     terminate(errcode);
 }

src/pifmrds/rds_wav.c

@@ -50,7 +50,7 @@ int main(int argc, char **argv) {
     char *in_file = argv[1];
     if(strcmp("NONE", argv[1]) == 0) in_file = NULL;
 
-    if(fm_mpx_open(in_file, LENGTH) != 0) {
+    if(fm_mpx_open(in_file, LENGTH, 0) != 0) {
         printf("Could not setup FM mulitplex generator.\n");
         return EXIT_FAILURE;
     }