For the improvement of coding efficiency, the H.264 standard uses new coding tools. Among the tools, motion estimation using smaller block sizes leads to higher correlation between the motion vectors of neighboring blocks. This characteristic of H.264 is useful for motion vector recovery to conceal a lost macroblock. In this paper, we propose the motion vector recovery method based on optical flow in H.264. We first determine optical flow region to alleviate the complexity, and choose initial value of flow velocity using neighboring motion vectors of a lost macroblock. And then the proposed method recovers the motion vectors of 4×4 blocks included in a lost macroblock using the weighted average of obtained flow velocities. Simulation results show that our proposed method gives higher objective and subjective visual qualities than conventional approaches.
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