Data compression for HDTV transmission and distribution

Studies on video compression for TV and HDTV applications have been carried out at the Research Centre of Radiotelevisione Italiana (RAI) since 1986. With the work accomplished in the framework of the European project EU 256, a contribution has been provided in the standardization activities of CMTT and ETSI for a codec to transmit conventional definition TV at 34 and 45 Mbit/s. The adopted video compression system is based on the use of DCT (Discrete Cosine Transform), motion compensation and entropy encoding. The same basic algorithms have been implemented in the EU 256 HDTV codec: the authors summarize the experiments carried out on the occasion of several international events. They also report some considerations on the following issues: picture quality at high compression ratio; choice of the distribution format; compatibility and multiple resolution levels; and the role of motion evaluation and compensation techniques to improve quality