Enhanced motion compensation algorithm based on second-order prediction

Several techniques based on the multiple reference frame scheme have been proposed to improve the motion prediction gain. Though these techniques yield higher prediction gain than the single reference frame scheme, they require tremendous computational complexity during the motion search procedure. Besides, blocking artifacts may be visible along the block boundaries, since each macroblock is predicted independently of its neighbors. To overcome these drawbacks, this paper proposes a novel motion compensation algorithm, based on the double reference frame (DRF), the double motion vector (DMV), and the searching position shifting (SPS) schemes. First, to reduce the motion vector bitrate and the computational complexity of motion search procedure, we constrain the number of reference frames to 2, and use only two motion vectors per block. Second, to alleviate the blocking artifacts and to get the better pel prediction, the searching position shifting scheme is introduced. Experimental results demonstrate that the proposed algorithm yields a 3-4 dB higher prediction gain than the single reference frame scheme. The subjective quality is also improved by alleviating the blocking artifacts.