Low-pass filter based VLSI oriented variable block size motion estimation algorithm for H.264

In this paper, a fast motion estimation algorithm, which is friendly to VLSI hardware implementation is proposed. This algorithm has such features: First, through "Haar" low-pass filter based subsampling, the computation complexity at each search position is reduced to about 25% of the original algorithm; Second, one modified motion vector prediction is provided to eliminate the data dependence among sub-partitions in the same macro block(MB). Based on this approach, parallel processing for variable block size motion estimation(VBSME) with integer pixel accuracy can be realized; Third, one "adaptive sub-search window" scheme is proposed to further reduce computation cost and it also can facilitate reference frame data reusing to reduce memory transfer from the external RAM to the onchip SRAM. The proposed VBSME algorithm is very suitable for parallel VLSI implementation.