关键词: 跳帧视频转码, 运动矢量合成, 运动矢量精细化

Abstract: In frame skipping transcoding，original motion vectors are used to recompose new ones for outgoing stream.However，these recomposed motion vectors may suffer larger error.In this paper we propose an adaptive motion vector refinement algorithm that classifies motion vectors in two groups.Small range refinement is applied for the group with small error.For the other group，the best motion vector is selected from original，predicted and recomposed motion vectors according to SAD（Sum of Absolute Difference）.Then larger range refinement is applied.Experimental results show that the proposed algorithm can effectively improve PSNR and reduce bit rate of the outgoing stream.

Key words: frame skipping transcoding, motion vector composition, motion vector refinement