Method and apparatus for encoding video signal with improved compression efficiency using model switching of sub pixel's motion estimation

The encoding method for increasing compression efficiency by sub-pixel motion estimation when the model switching in accordance with an embodiment of the present invention comprises the steps of calculating a motion vector of a pixel existing on a block, the first model, and using the value of the motion vector the selection step, step, and a small model the prediction error for comparing the prediction error and the prediction error of the second model is produced in which the first model generator for generating a second model, and the sub-pixels according to the selected model, and for performing a motion prediction. Sub-pixels, an integer pixel, the switching model, the motion estimate (motion estimation)