For the motion estimation in the high efficiency video coding

a fast fractional-pixel prediction algorithm is proposed

which fits sum of absolute difference（SAD） based on the quadratic function to determine the optimal half-pixel point

the sub-optimal half-pixel point is determined by SAD of the integer-pixel points adjacent to the candidate sub-optimal half-pixel point

and finally the area of 3 × 3 formed by the optimal half-pixel point and the sub-optimal half-pixel point is searched for optimal quarter-pixel point. The SAD of the half-pixel point is not calculated again when determining the sub-optimal half-pixel point. Experimental results show that the algorithm can effectively reduce the time of sub-pixel prediction and computational complexity when the image quality is almost unchanged.