A variable bit rate video codec for ATM networks and its robustness against cell losses

A video codec for ATM (Asynchronous data Transfer Mode), which is the transfer scheme in the era of B-ISDN (broadband aspects of ISDN) is constructed and the performance is evaluated. The experimental equipment can realize the variable-rate coded video transmission corresponding to CCIR 601 recommendation, through the experimental switching network. The periodic cyclic refresh, packeting of the coded information, and the interframe prediction DCT layered coding are employed, realizing a robustness against the cell loss which is the cause of a drastic image quality deterioration in ATM. As a result of the subjective evaluation experiment, the image quality of MOS 3.5 or above is obtained for the cell loss ratio of 10−6 using only the cyclic refresh and the packeting of the coded information, and 10−2 to 10−4 of low-priority order information using the interframe prediction DCT layered coding.