always triple check your patchen

v4l2/grabvidseq.c

@@ -129,6 +129,7 @@ while ((opt = getopt(argc, argv, "d:ghn:o:O:p:s:uv")) != -1) {
 						optarg);
 					exit(1);
 					}
+				period *= 1e6;
 				break;
 		case 's':	parse_WxH(optarg, &width, &height);
 				break;