Abstract: A data demultiplexer in a media demultiplexer dissolves a bit stream into video packets and audio packets. A CRC calculating unit subjects data from a CRC character isolating unit to the same calculation as performed at the encoding end and outputs a result of calculation to an error information adding unit. The error information adding unit compares the result of calculation with a CRC character attached to the video packet so as to determine whether they match. The error information adding unit adds error information based on a result of determination to the video packet. The resultant revised video packet is output to a video decoder via a buffer.