In order to avoid content deteriorations caused by embedment of a digital
watermark into a moving picture, a process to search a picture for a
motion and a process to filter a picture for medical care must be carried
out, raising a processing cost. It is thus difficult to implement
equipment for processing such pictures at a low cost. In a compound
apparatus for encoding compressed code of a moving picture by employing a
unit for embedding a digital watermark into a picture, a
digital-watermark embedment quantity is determined by using a motion
vector and a quantization parameter in a process to embed a digital
watermark into the picture. It is thus no longer necessary to carry out
the process to search a picture for a motion and the process to filter a
picture for medical care for embedment of a digital watermark so that the
cost of the entire apparatus can be reduced substantially.