Robust and E cient Video CommunicationBased on Combined Source - and Channel

A video communication system based on combined source-and channel coding is proposed. The proposed system uses a subband video coder structure in combination with power-constrained channel-optimized vector quantiza-tion (PCCOVQ) to achieve eecient and robust transmission of the video signal over a channel with multidimensional PAM signaling. The side information is protected by using a suuciently large minimum distance of the PAM signal constellation. This ensures error free transmission for the channel-optimized case, and graceful degradation for channel mismatch situations. For the main information, however, PCCOVQ with direct mapping from the source parameter space to the channel (modulation) space is used. A video communication system based on the H.263 video coder is used as a reference. The proposed system compares favorably to the reference system, and ooers graceful degradation for channel mismatch situations.