if record file error,prompt and exit

@@ -1139,6 +1139,11 @@ int load_record_info(char * record_info)
 		}
 	}
 
+	if (media_files.size() == 0){
+		printf("no teacher or student files found in:%s", record_info);
+		return -2;
+	}
+
 	unifiy_start_time();
 
 	add_media_infos();