parse_image_size(&frame_width, &frame_height, arg); if (frame_width <= 0 || frame_height <= 0) {
if (parse_image_size(&frame_width, &frame_height, arg) < 0) {
static void opt_frame_size(const char *arg){    parse_image_size(&frame_width, &frame_height, arg);    if (frame_width <= 0 || frame_height <= 0) {        fprintf(stderr, "Incorrect frame size\n");        exit(1);    }    if ((frame_width % 2) != 0 || (frame_height % 2) != 0) {        fprintf(stderr, "Frame size must be a multiple of 2\n");        exit(1);    }}