Analysis of coding efficiency of motion-compensated interpolation at the decoder in distributed video coding

This paper analyzes the coding efficiency of distributed video coding (DVC) schemes that perform motion-compensated interpolation at the decoder. The decoder has access only to the key frames when generating the side information for intermediate frames. This fact introduces a displacement estimation error that depends on several factors: 1) the overall motion complexity; 2) the temporal coherence of the motion field; 3) the temporal distance between successive key frames. Adopting a state-space model and a Kalman filtering framework, we obtain an estimate of the displacement error variance. This is used to determine the rate-distortion function of the overall coding scheme, that takes into account both intra-coded key frames and DVC-coded frames. The proposed model shows that motion-compensated interpolation is unable to achieve the coding efficiency of conventional motion-compensated predictive coding.