Motion estimation (ME) plays an important role in video coding system

since it could significantly affect the output quality of an encoded sequence. This paper proposes a fast adaptive ME algorithm based on the judgment of the predictive motion vector (PMV). This proposed algorithm takes advantage of the correlation of neighboring blocks to adaptively decide the threshold for judging the stationary regions. And this algorithm sorts the PMV into several regions by its direction and uses different search patterns

respectively. Compared with the former algorithm

this algorithm considers the characteristic of different sequences and thus

it is more flexible than before. Experimental result shows that this algorithm reduces computation complexity variously for different sequence under the premise that the PSNR does not lose.