A Statistical Analysis of MPEG-2 Picture Quality for Television Broadcasting

The relationship between bit rate and picture quality is a major issue of interest for digital broadcasting services. To evaluate coding performance of the MPEG-2 video standard, subjective assessment tests were conducted for both Main Profile and Simple Profile, as well as NTSC. Since picture quality in digital coding depends largely on such picture characteristics as spatial detail and motion, estimation of the picture quality of TV program material requires statistical analysis. This paper defines criticality, a quantitative measure of difficulty for digital coding, to analyze the picture quality of TV programs statistically. Equipment has been developed to measure criticality and to study a large number of TV program materials over a period of one week. Based on the statistical evaluation of picture degradation in real TV programs, the authors have concluded that approximately 9 Mbits/sec is an appropriate bit rate for digital broadcasting to maintain picture quality comparable to that of studio NTSC and to provide excellent quality in more than 99.9% of the broadcasting hours.