A low bit-rate video codec based on two-dimensional mesh motion compensation with adaptive interpolation

Visual communication over low bandwidth channels, such as the telephone lin e, requires high compression. Motion estimation and compensation techniques play an important role in achieving high compression by reducing the tempo ral redundancy inherent in video sequences. Current video coding standards employ block-matching algorithm to perform motion estimation that produces visually annoying blocking artifacts at low bit rate. In contrast, 2-D mesh motion compensation produces blocking free prediction by generating a smoo th full motion field from the set of node motion vectors using spatial inte rpolation, However, the assumption of a globally smooth motion field is not valid for most natural occurring scenes, where motion discontinuities exis t due to moving objects. In this paper, we propose a post-processing scheme that refines the set of node motion vectors obtained by the 2-D mesh motio n estimation. The approach is to selectively break the smoothness constrain t of 2-D mesh far patches that contain motion boundaries by changing the in terpolation patterns, Experimental results show improvements in both PSNR a nd perceptual quality over the 2-D mesh motion compensation and a block-bas ed standard video-coding standard H.263.