Motion estimation (ME) is a computation and data intensive processing in video coding system. In MPEG-2 to H.264 transcoding, ME of H.264 encoder end is simplified by reusing MPEG-2 motion vector (MV) to curtail search window. However reusing MPEG-2 MV brings difficulty in applying search window reuse method, which plays a critical role in bandwidth reduction. Based on method proposed in [1], a hardware architecture is proposed for integer motion estimation (IME) of MPEG-2 to H.264 transcoding. Experiment results shows the proposed architecture’s bandwidth is 70.6% of H.264 regular IME (Level C+ scheme, 2 MB stitched), while the on-chip memory is 11.7% of that.