In the paper

a new motion-object-based shape coding called CSSAS (curvature scale space adaptive arithmetic shape coding) is proposed.There are two coding modes

the intra and inter modes.In the intra mode

the modified CSS theory is used to extract feature points of the shape curve of arbitrary shape video object(VO) at different scales.All of the feature points are encoded by adaptive arithmetic encoding.In the inter mode

a CSSI-based (Curvature scales space image-based) motion compensation/estimation algorithm of arbitrary shape VO is proposed.The matched segments of shape are coded by using arc length index algorithm and the mismatched segments are coded by using intra CSSAS algorithm.Simulation results show that the proposed method is much better than CAE of MPEG-4 VM in coding efficiency (in inter mode

Dn≥threshold) and subjective quality for both intra and inter modes.