H.264 video standard, in spite of its high quality, is too time-consuming for widespread acceptance in video applications, mainly due to its computationally complex motion estimation (ME). To reduce this complexity, we propose motion continuity hypothesis, which means that all motion vectors (MVs) of a block are usually located in a small area. This area is formalized as modified valid region (MVR), an improved version of valid region which is proposed by the present authors in a previous paper. Then, this paper develops a new fastME algorithm for H.264, called MVR-based fast ME (MVRF), which searches only a much smaller area in reference frames(RFs) for motion estimation than full search
264 does, so it reduces up to 43% search pixels. MVRF is so deliberately chosen that on average, up to 98% MVs determined by MVRF coincide with those by full search H.264, therefore keeping the recovery quality and bit-rate almost the same as those of full search H.264.