Block matching motion estimation(BMME) plays a very important role in video coding.The performance of BMME greatly affects the quality of the encoded bit stream.Full Search(FS) is the optimal algorithm for BMME.But its tremendous computation payload is unaffordable for practical applications

especially for real-time applications.To overcome this problem

a lot of fast algorithms were developed.This paper presents an adaptive fast motion-estimation algorithm based on H.264.Taking advantage of motion-vectors of the nearby macro-blocks to find the original searching central position and determine the size of the searching zone.Compared with the former algorithms with fixed searching zone

this algorithm is more flexible and can combine with any other fast motion estimation algorithm.Experimeotal results show that the algorithm can reduce computation amount variously by different motion-sequence under the premise don't reduce the PNSR.