func NewVideoWriter(filename string,
	fourcc int, fps float32,
	frame_width, frame_height,
	is_color int) *VideoWriter {

	size := C.cvSize(C.int(frame_width), C.int(frame_height))
	filename_c := C.CString(filename)
	defer C.free(unsafe.Pointer(filename_c))

	rv := C.cvCreateVideoWriter(filename_c,
		C.int(fourcc), C.double(fps), size, C.int(is_color),
	)
	return (*VideoWriter)(rv)
}
func NewVideoWriter(filename string,
	fourcc int, fps float32,
	frame_width, frame_height,
	is_color int) *VideoWriter {

	size := C.cvSize(C.int(frame_width), C.int(frame_height))
	filename_c := C.CString(filename)
	defer C.free(unsafe.Pointer(filename_c))

	rv := C.cvCreateVideoWriter(filename_c,
		C.int(fourcc), C.double(fps), size, C.int(is_color),
	)
	return (*VideoWriter)(rv)
}
/* initialize video file writer */