An efficient motion estimation technique based on a rate-distortion criterion

We present an efficient motion estimation algorithm where motion vectors are selected based on a rate-distortion criterion. The algorithm minimizes the rate subject to a constraint on overall distortion by optimizing jointly the motion vector coder and the residual coder. As the joint optimization is generally very demanding, we propose methods where the rate-distortion performance of the residual coder is approximated by parametric functions. This results in a substantial reduction in computational complexity while sacrificing only a small loss in performance. Experimental results indicate that the proposed algorithm can improve the performance of H.261- and H.263-based video coders significantly while still generating H.261/H.263 decodable bit streams, respectively.