Basic characteristics of variable rate interframe video coding

Recently, interest has been increasing greatly in the various services and possibilities offered by the new communication media. At the same time, the demand for higher‐speed communication also has increased. Therefore, flexible systems based on ATM (asynchronous transfer mode) have received particular attention because they can meet these demands by transmitting various types of information in a unified form. In this case, the transmission method can utilize effectively the variable rate characteristics of the information sources. Thus, the understanding of basic characteristics of the coded information sources becomes important. This paper investigates the basic characteristics of the variable rate video coding from this viewpoint. The interframe coding method is considered and the burst characteristics of the information as well as the improvement due to variable rate coding are analyzed, using simulation methods. The results relating to video conference scenes show that the peak rate is about three times as much as the average rate and the quality improvement expressed in minimum SNR is about 5 to 10 dB.