An efficient computation-constrained block-based motion estimation algorithm for low bit rate video coding

We present an efficient computation constrained block-based motion vector estimation algorithm for low bit rate video coding that offers good tradeoffs between motion estimation distortion and number of computations. A reliable predictor determines the search origin. An efficient search pattern exploits structural constraints within the motion field. A flexible cost measure used to terminate the search allows simultaneous control of the motion estimation distortion and the computational cost. Experimental results demonstrate the viability of the proposed algorithm in low bit rate video coding applications, achieving essentially the same levels of rate-distortion performance and subjective quality as that of the full search algorithm when used by the UBC H.263+ video coding reference software. However the proposed motion estimation algorithm provides substantially higher encoding speed as well as graceful computational degradation capabilities.