Add an option to encode/decode without FEC

main.c

@@ -25,7 +25,7 @@
 
 void exit_usage()
 {
-	fprintf(stderr, "Usage: ssdv [-e|-d] [-t <percentage>] [-c <callsign>] [-i <id>] [<in file>] [<out file>]\n");
+	fprintf(stderr, "Usage: ssdv [-e|-d] [-n] [-t <percentage>] [-c <callsign>] [-i <id>] [<in file>] [<out file>]\n");
 	exit(-1);
 }
 
@@ -35,6 +35,7 @@ int main(int argc, char *argv[])
 	FILE *fin = stdin;
 	FILE *fout = stdout;
 	char encode = -1;
+	char fec = -1;
 	int droptest = 0;
 	char callsign[7];
 	uint8_t image_id = 0;
@@ -46,12 +47,13 @@ int main(int argc, char *argv[])
 	callsign[0] = '\0';
 	
 	opterr = 0;
-	while((c = getopt(argc, argv, "edc:i:t:")) != -1)
+	while((c = getopt(argc, argv, "ednc:i:t:")) != -1)
 	{
 		switch(c)
 		{
 		case 'e': encode = 1; break;
 		case 'd': encode = 0; break;
+		case 'n': fec = 0; break;
 		case 'c':
 			if(strlen(optarg) > 6)
 				fprintf(stderr, "Warning: callsign is longer than 6 characters.\n");
@@ -105,14 +107,16 @@ int main(int argc, char *argv[])
 		jpeg = malloc(jpeg_length);
 		ssdv_dec_set_buffer(&ssdv, jpeg, jpeg_length);
 		
+		ssdv_set_fec(&ssdv, (fec ? 1 : 0));
+		
 		i = 0;
-		while(fread(pkt, 1, SSDV_PKT_SIZE, fin) > 0)
+		while(fread(pkt, 1, (fec ? SSDV_PKT_SIZE : SSDV_PKT_SIZE - SSDV_PKT_SIZE_RSCODES), fin) > 0)
 		{
 			/* Drop % of packets */
 			if(droptest && (rand() / (RAND_MAX / 100) < droptest)) continue;
 			
 			/* Test the packet is valid */
-			if(ssdv_dec_is_packet(pkt, NULL) != 0) continue;
+			if(ssdv_dec_is_packet(pkt, NULL, (fec ? 1 : 0)) != 0) continue;
 			
 			/* Feed it to the decoder */
 			ssdv_dec_feed(&ssdv, pkt);
@@ -130,6 +134,7 @@ int main(int argc, char *argv[])
 	case 1: /* Encode */
 		ssdv_enc_init(&ssdv, callsign, image_id);
 		ssdv_enc_set_buffer(&ssdv, pkt);
+		ssdv_set_fec(&ssdv, (fec ? 1 : 0));
 		
 		i = 0;
 		
@@ -158,7 +163,7 @@ int main(int argc, char *argv[])
 				return(-1);
 			}
 			
-			fwrite(pkt, 1, SSDV_PKT_SIZE, fout);
+			fwrite(pkt, 1, (fec ? SSDV_PKT_SIZE : SSDV_PKT_SIZE - SSDV_PKT_SIZE_RSCODES), fout);
 			i++;
 		}
 		

ssdv.c

@@ -820,6 +820,7 @@ char ssdv_enc_init(ssdv_t *s, char *callsign, uint8_t image_id)
 	s->image_id = image_id;
 	s->callsign = encode_callsign(callsign);
 	s->mode = S_ENCODING;
+	s->fec = 1;
 	
 	/* Prepare the output JPEG tables */
 	s->ddqt[0] = dtblcpy(s, std_dqt0, sizeof(std_dqt0));
@@ -970,7 +971,7 @@ char ssdv_enc_get_packet(ssdv_t *s)
 				s->out[i++] = x & 0xFF;
 				
 				/* Generate the RS codes */
-				encode_rs_8(&s->out[1], &s->out[i], 0);
+				if(s->fec == 1) encode_rs_8(&s->out[1], &s->out[i], 0);
 				
 				s->packet_id++;
 				
@@ -1100,6 +1101,7 @@ char ssdv_dec_init(ssdv_t *s)
 	/* The packet data should contain only scan data, no headers */
 	s->state = S_HUFF;
 	s->mode = S_DECODING;
+	s->fec = 1;
 	
 	/* Prepare the source JPEG tables */
 	s->sdqt[0] = stblcpy(s, std_dqt0, sizeof(std_dqt0));
@@ -1260,7 +1262,7 @@ char ssdv_dec_get_jpeg(ssdv_t *s, uint8_t **jpeg, size_t *length)
 	return(SSDV_OK);
 }
 
-char ssdv_dec_is_packet(uint8_t *packet, int *errors)
+char ssdv_dec_is_packet(uint8_t *packet, int *errors, uint8_t fec)
 {
 	uint8_t pkt[SSDV_PKT_SIZE];
 	ssdv_packet_info_t p;
@@ -1272,10 +1274,17 @@ char ssdv_dec_is_packet(uint8_t *packet, int *errors)
 	pkt[0] = 0x55;
 	pkt[1] = 0x66;
 	
+	if(fec == 0)
+	{
+		if(errors) *errors = 0;
+	}
+	else if(fec == 1)
+	{
 		/* Run the reed-solomon decoder */
 		i = decode_rs_8(&pkt[1], 0, 0, 0);
 		if(i < 0) return(-1); /* Reed-solomon decoder failed */
 		if(errors) *errors = i;
+	}
 	
 	/* Sanity checks */
 	if(pkt[1] != 0x66) return(-1);
@@ -1320,3 +1329,8 @@ void ssdv_dec_header(ssdv_packet_info_t *info, uint8_t *packet)
 
 /*****************************************************************************/
 
+void ssdv_set_fec(ssdv_t *s, uint8_t fec)
+{
+	s->fec = fec;
+}
+

ssdv.h

@@ -45,6 +45,9 @@ extern "C" {
 
 typedef struct
 {
+	/* Flags */
+	uint8_t fec; /* 0 == None, 1 = RS8 */
+	
 	/* Image information */
 	uint16_t width;
 	uint16_t height;
@@ -141,9 +144,12 @@ extern char ssdv_dec_set_buffer(ssdv_t *s, uint8_t *buffer, size_t length);
 extern char ssdv_dec_feed(ssdv_t *s, uint8_t *packet);
 extern char ssdv_dec_get_jpeg(ssdv_t *s, uint8_t **jpeg, size_t *length);
 
-extern char ssdv_dec_is_packet(uint8_t *packet, int *errors);
+extern char ssdv_dec_is_packet(uint8_t *packet, int *errors, uint8_t fec);
 extern void ssdv_dec_header(ssdv_packet_info_t *info, uint8_t *packet);
 
+/* Common */
+extern void ssdv_set_fec(ssdv_t *s, uint8_t fec);
+
 #ifdef __cplusplus
 }
 #endif