Approximate criteria for the MPEG-2 motion estimation

This paper proposes three kinds of approximate criteria for the MPEG-2 motion estimation. They are based on the behavior of motion-compensated prediction, which uses a kind of averaging. A simplified motion estimation method is derived as a result of applying the criteria to the MPEG-2 test model motion estimator. The test model motion estimator consists of three steps: (1) finding full-pel motion vectors; (2) refining the vectors to half-pel accuracy; and (3) evaluating either the interpolative or the dual-prime prediction mode, which is a combination of the vectors. Since the second and the third steps require a huge number of data transfers, the circuit size of the steps becomes comparable to that of the first step. The simplified method solves this problem while keeping practically equivalent performance. In the second and the third steps, the simplified method reduces the number of necessary computations to less than 1%, and that of data transfers to less than 8% of the test model motion estimator. Even though the simplified method only modifies the second and third steps, the number of total data transfers, including those for the first step, is also reduced to 27% in main profile or 20% in simple profile