When decoding, don't require packets in the input to be aligned to the packet size

README

@@ -13,7 +13,7 @@ $ ssdv -e -c TEST01 -i ID input.jpeg output.bin
 
 This encodes the 'input.jpeg' image file into SSDV packets stored in the 'output.bin' file. TEST01 (the callsign, an alphanumeric string up to 6 characters) and ID (a number from 0-255) are encoded into the header of each packet. The ID should be changed for each new image transmitted to allow the decoder to identify when a new image begins.
 
-The output file contains a series of SSDV packets, each packet always being 256 bytes in length. Additional data may be transmitted between each packet, the decoder will ignore this.
+The output file contains a series of fixed-length SSDV packets (default 256 bytes). Additional data may be transmitted between each packet, the decoder will ignore this.
 
 DECODING
 

main.c

@@ -63,6 +63,7 @@ int main(int argc, char *argv[])
 	int8_t quality = 4;
 	int pkt_length = SSDV_PKT_SIZE;
 	ssdv_t ssdv;
+	int skipped;
 	
 	uint8_t pkt[SSDV_PKT_SIZE], b[128], *jpeg;
 	size_t jpeg_length;
@@ -141,18 +142,38 @@ int main(int argc, char *argv[])
 		ssdv_dec_set_buffer(&ssdv, jpeg, jpeg_length);
 		
 		i = 0;
-		while(fread(pkt, 1, pkt_length, fin) > 0)
+		while(fread(pkt, pkt_length, 1, fin) > 0)
 		{
 			/* Drop % of packets */
 			if(droptest && (rand() / (RAND_MAX / 100) < droptest)) continue;
 			
 			/* Test the packet is valid */
-			if(ssdv_dec_is_packet(pkt, pkt_length, &errors) != 0) continue;
+			skipped = 0;
+			while((c = ssdv_dec_is_packet(pkt, pkt_length, &errors)) != 0)
+			{
+				/* Read 1 byte at a time until a new packet is found */
+				memmove(&pkt[0], &pkt[1], pkt_length - 1);
+				
+				if(fread(&pkt[pkt_length - 1], 1, 1, fin) <= 0)
+				{
+					break;
+				}
+				
+				skipped++;
+			}
+			
+			/* No valid packet was found before EOF */
+			if(c != 0) break;
 			
 			if(verbose)
 			{
 				ssdv_packet_info_t p;
 				
+				if(skipped > 0)
+				{
+					fprintf(stderr, "Skipped %d bytes.\n", skipped);
+				}
+				
 				ssdv_dec_header(&p, pkt);
 				fprintf(stderr, "Decoded image packet. Callsign: %s, Image ID: %d, Resolution: %dx%d, Packet ID: %d (%d errors corrected)\n"
 				                ">> Type: %d, Quality: %d, EOI: %d, MCU Mode: %d, MCU Offset: %d, MCU ID: %d/%d\n",