Performance of codecs for bit-rate reduction applied on conventional TV and HDTV signals

There is an urgent need of systems to allow the transmission of conventional TV and HDTV signals through the presently available digital networks. This is a demanding task since the transmission of a 4:2:2 signal is very cumbersome in terms of required data capacity, i.e. more than 165 Mbps for the active picture period. The difficulties increase in the case of HDTV signals, being the data rate of the order of 950 Mbps. For this reason studies have been undertaken to devise compression techniques which can provide a suitable quality with a bit-rate of 30-45 Mbps for conventional TV and about 140 Mbps for HDTV. The authors outline the main features of the adopted compression algorithms and describes the structure of the implemented codecs. Emphasis is given to the features of the system having a direct impact on the performance of the codecs in terms of picture quality, easy implementation, flexibility and error resilience. The results of preliminary tests on the actual hardware are given. Finally, a survey on the future applications of such coding system is presented