A low bit-rate video codec based on Control Grid Interpolation motion compensation using edge feature

Block-based motion estimation and compensation are the most popular techniques for video coding. However, as the shape and the structure of an object in a picture are arbitrary, the performance of such conventional block-based methods may not be satisfactory. Moreover, the human visual system is sensitive to the break of curvature produced by the straight-line matching patterns, which are adopted by adaptive Control Grid Interpolation (CGI) motion estimation and H.26L. This results in annoying artifact in an overlapped region in real sequences. In this paper, a very low bit-rate video codec employing CGI motion estimation with the edge-oriented interpolation patterns is proposed. The aim is to improve the coding performance, which gives better subjective and objective quality than that of the conventional coding methods at the same bit-rate. The approach is to selectively break the smoothness constraint of CGI for patches that contain motion boundaries by switching to the edge-oriented interpolation pattern. Experimental results show improvements in both PSNR and perceptual quality over the adaptive CGI motion compensation and a block-based video coding standard H.26L.