H.263-video coding recommendation for PSTN videophone and multimedia

Presents an overview of JTU-T Recommendation H.263. In particular, the operation and impact on quality and bit-rate of the four H.263 Annexes (D, E, F and G) which specify optional enhanced modes of operation are discussed, with supporting results. The effectiveness of the various options is seen to depend upon the type of sequence and the frame rate, making it clear that for optimum performance a real codec must include means to make appropriate decisions about which options to invoke for maximum performance under given operating conditions. Finally, comparisons with H.261 indicate a significant performance gain for H.263, of the order of 2 to 3 dB