A method for estimating a motion vector for transcoding digital video, the method characterized in comprising: selecting a direction of an adjustment vector for estimation of a motion vector within a search region being centered around a reference motion vector calculated from an input bit stream (S11, S12, S13, S14, S15, S20, S21), the adjustment vector being a motion vector included in the search region; and selecting the adjustment vector having a minimum SAD among a plurality of SADs included within the search region corresponding to the direction of the adjustment vector (S16, S17, S18, S19, S22); and estimating the motion vector by summing the selected adjustment vector and the reference motion vector; wherein selecting the direction of the adjustment vector further comprises: calculating a SAD with respect to a plurality of adjustment vectors being centered at least one pixel around the reference motion vector; selecting a first adjustment vector having a minimum value among a plurality of SADs and a second adjustment vector having a next lowest minimum value among the plurality of SADs; calculating a third adjustment vector by adding the first adjustment vector and the second adjustment vector; selecting an axis of the first adjustment vector as the direction of the adjustment vector if the third adjustment vector has a zero value in at least an x-vector or a y-vector coordinate (S14, S15); and selecting a direction of a quadrant of the third adjustment vector as the direction of the adjustment vector if the third adjustment vector has a non-zero value in both the x-vector coordinate and the y-vector coordinate (S14, S20, S21). selecting a direction of an adjustment vector for estimation of a motion vector within a search region being centered around a reference motion vector calculated from an input bit stream (S11, S12, S13, S14, S15, S20, S21), the adjustment vector being a motion vector included in the search region; and selecting the adjustment vector having a minimum SAD among a plurality of SADs included within the search region corresponding to the direction of the adjustment vector (S16, S17, S18, S19, S22); and estimating the motion vector by summing the selected adjustment vector and the reference motion vector; wherein selecting the direction of the adjustment vector further comprises: calculating a SAD with respect to a plurality of adjustment vectors being centered at least one pixel around the reference motion vector; selecting a first adjustment vector having a minimum value among a plurality of SADs and a second adjustment vector having a next lowest minimum value among the plurality of SADs; calculating a third adjustment vector by adding the first adjustment vector and the second adjustment vector; selecting an axis of the first adjustment vector as the direction of the adjustment vector if the third adjustment vector has a zero value in at least an x-vector or a y-vector coordinate (S14, S15); and selecting a direction of a quadrant of the third adjustment vector as the direction of the adjustment vector if the third adjustment vector has a non-zero value in both the x-vector coordinate and the y-vector coordinate (S14, S20, S21). calculating a SAD with respect to a plurality of adjustment vectors being centered at least one pixel around the reference motion vector; selecting a first adjustment vector having a minimum value among a plurality of SADs and a second adjustment vector having a next lowest minimum value among the plurality of SADs; calculating a third adjustment vector by adding the first adjustment vector and the second adjustment vector; selecting an axis of the first adjustment vector as the direction of the adjustment vector if the third adjustment vector has a zero value in at least an x-vector or a y-vector coordinate (S14, S15); and selecting a direction of a quadrant of the third adjustment vector as the direction of the adjustment vector if the third adjustment vector has a non-zero value in both the x-vector coordinate and the y-vector coordinate (S14, S20, S21).