Objective and Subjective Measures of MPEG Video Quality

In 1996, the American National Standards Institute (ANSI) adopted ANSI T1.801.03, which presents a number of new objective video quality metrics for quantifying the effects of digital compression and transmission impairments. The measurements in ANSI T1.801.03 were selected based on an extensive multilaboratory quality assessment study that included video systems from bit rates of 64 kbit/sec to 45 Mbit/sec and video test scenes that spanned a wide range of spatial and temporal coding difficulties. The set of objective video quality measurements effectively accounted for subjective judgments by human viewers. While 25 video systems were tested, this multilaboratory study did not include MPEG video systems, and did not cover any bit rates between 1.6 and 10 Mbit/sec. This paper presents the results from two MPEG studies designed to fill in the bit-rate gap in the previous multilaboratory study. In these studies, we concentrated on bit rates from 1.5 8.3 Mbit/sec and examined the performance of MPEG 1 and MPEG 2 codecs (coder-decoders) specifically. The effectiveness of the ANSI standard objective video quality metrics was examined for these bit rates and coding technologies. Our analysis revealed that the objective video quality metrics primarily measure four principal components of video quality: added edges, lost edges, added motion, and lost motion; we found that parameters selected from these principal components can be used as effective predictors of subjective quality ratings for entertainment video systems.