Rate-distortion optimized motion estimation for error resilient video coding
Rate-distortion optimized motion compensation was originally proposed to improve the source coding efficiency of low bit-rate video coding. This paper investigates the potential benefits of extensions to explicitly handle transmission over lossy networks. The important impact of appropriate motion compensation on error resilience is identified and exploited to enhance performance. The expected end-to-end distortion, rather than the source coding distortion, is employed in the rate-distortion optimization criterion. The accuracy of the distortion estimate is crucial when optimizing over the motion vectors (as compared to the less sensitive inter/intra mode decision), and is ensured here by adopting the recursive optimal per-pixel estimate (ROPE) method. The main objective is to assess the gains achievable by such source-channel motion compensation, and this is given priority over complexity considerations. Significant performance gains in simulation demonstrate the potential of rate-distortion optimized motion compensation to improve the error resilience of video coding.