Video preprocessing in MPEG-2 compression systems

Increased use of compressed video signals in broadcasting has led to the expectation that bit rates will fall and quality will be maintained. Although it is true that compression encoders have decreased in cost and continue to improve in performance, the overall performance of a digital chain that may include more than one compression stage remains limited by practical factors that concern the quality of the video input to the compressor. If this input is impaired for example, by noise, interference, composite decoding, and film scanning artifacts, etc., the subsequent compression process may not perform well. This paper explores some of the factors that affect the performance of practical MPEG-2 compression systems and suggestions for dealing with them.