1. A motion estimation method of a video encoder, the method comprising: a first step of performing, by a motion estimator of the video encoder, a full search within a ±4 pixel search region in a first video frame for a 4×4 pixel block of a second video frame, wherein original video resolutions of the first video frame and the second video frame are reduced by sub-sampling to a ¼ resolution of the original video frames, to detect two motion vector candidates; a second step of calculating, by the motion estimator of the video encoder, a sum (A) of absolute differences between a mean intensity of a 16×16 pixel macroblock of the current video frame and an intensity of each pixel of the macroblock, at the original video resolution; and if the sum A value calculated in the second step is smaller than a predetermined threshold value, then at least one of; a third step of performing, by the motion estimator of the video encoder, a partial search within a ±1 pixel search region for a 8×8 pixel macroblock, wherein the video data is reduced to ½ the resolution of the original video frames, to detect a motion vector candidate; and a fourth step of performing, by the motion estimator of the video encoder, a partial search within a ±1 search region for a 16×16 pixel macroblock in the original video resolution, to detect a final motion vector.