1. A method for encoding video, comprising: determining early termination based on the value of a sum of absolute difference (SAD 0 ); performing motion prediction using a motion vector from a previous frame as a prediction point; using the prediction point as the center to obtain the integral motion vector by conducting a 3×3 cross searching until a minimum sum of absolute difference (minSAD) is located at the center of the cross; and predicting a location of a half-pixel point based upon a point corresponding to the integral motion vector, values of the minimum sum of absolute difference of other four cross points.