A Vertically Symmetrical Linear Model-Based Fractional-Pixel Motion Estimation Algorithm for H.264/AVC Encoder

Integer-pixel motion estimation (IME) runtime in the H.264 encoder takes up over 50% of the total runtime. In which, many IME algorithms have been developed up to now. On the other hand, fractional-pixel motion estimation (FME) part also occupies about 40% of the total motion estimation runtime. After performing the FME process, 1-3 (dB) PSNR improvement can be achieved. The FME part, therefore, has been becoming an important research topic for video coding applications. Conventional FME algorithms such as the full fractional-pixel search require some search points as well as high memory usage due to the interpolation process. In this paper, a vertically symmetrical linear model-based FME algorithm including a grouping strategy is proposed to reduce the computational complexity and improve the performances without regard to the interpolation process. The simulation results show the proposed algorithm can produce slightly better performances compared with the existing prediction method.