A codec for HDTV

A high-quality digital video codec has been developed for the Zenith/AT&T HDTV system. It adaptively selects between two transmission modes with differing rates and robustness. The codec works on an image progressively scanned with 1575 scan lines every 1/30th of a second and achieves a compression ratio of approximately 50 to 1. The high compression ratio facilitates robust transmission of the compressed HDTV signal within an NTSC taboo channel. Transparent image quality is achieved using motion compensated transform coding coupled with a perceptual criterion to determine the quantization accuracy required for each transform coefficient. The codec has been designed to minimize complexity and memory in the receiver. >