Overview of the p×64 kbit/s video coding standard

Reviewer: Dionysius P. Huijsmans

The Consultative Committee for International Telephone and Telegraph (CCITT) standard for visual telephony, including videoteleconferencing, using the ISDN network covers a range ( p = 1,2,…, 3 0) of bitspeeds; the higher p is, the better the quality and the more complex frames can get. The standard uses another standard videophone format from CCITT—common intermediate format (CIF) and quarter CIF (QCIF), with uncompressed bitrates of 36.45 and 9.115 Mbit/s respectively. Compression rates can be as high as 50:1. Liou describes the hierarchical structure of CIF and QCIF. The encoder part of this standard uses CCITT's H-261 compression algorithm. It combines lossy discrete cosine transform, lossless entropy, and differential pulse code modulation interframe and intraframe coding. The decoder part is described in less detail. Finally, a number of frames transmitted at different bitrates are shown for comparison. This overview is a bit short, but it achieves all that the author wanted. It is only meant to inform a general audience about the existence of the standard, and is not suited to give a good insight into its precise structure. Interested readers will have to consult the documentation on the various standards themselves. The references provide an adequate entry to this documentation.