Low power distance measurement unit for real-time hardware motion estimators

Real-time video encoding often demands hardware motion estimators, even when fast search algorithms are adopted. With the widespread usage of portable handheld devices that support digital video coding, low power consideration becomes a central limiting constraint. Consequently, adaptive search algorithms and special hardware architectures have been recently proposed to perform motion estimation in portable and autonomous devices. This paper proposes a new efficient carry-free arithmetic unit to compute the minimum distance in block matching motion estimation. The operation of the proposed unit is independent of the adopted search algorithm and of the used prediction error metric, simultaneously speeding up motion estimation and significantly reducing the power consumption. Moreover, its low latency is particularly advantageous when partial distance techniques are applied to further reduce the power consumption. Experimental results show that the proposed unit allows to reduce the computation time in about 40% and it consumes 50% less power than commonly adopted architectures.