Fast variable block motion estimation based on adaptive search for H.264/AVC system

H.264/AVC with variable block size coding can offer a better motion-compensation than the previous coding standards. However, its complexity is extremely high since there are 41 motion vectors to be computed for one macro-block. We propose a fast algorithm based on the adaptive searching approach from the top block to the bottom one. With the center-point moving technique, the searching range can be reduced while keeping the same coding quality. For smoothing area, the large block mode can be quickly found to save the computational cost. This algorithm also can track the edge blocks and process them with small block mode to achieve better image quality. Simulations show that our proposed algorithm can save 90%~97% motion searching time under H.264 program JM8.6 while PSNR only decreases about 0.05 dB.