A generalized fast motion estimation algorithm using external and internal stop search techniques for H.264 video coding standard

In this paper, a set of computationally efficient accurate skipping techniques are proposed for motion estimation. First, a Partial Internal Stop Search (ISS) technique which utilizes an accurate adaptive threshold model is exploited to skip the internal SAD (Sum of Absolute Difference) operations between the current and reference blocks. Second, an External Stop Search (ESS) technique greatly reduces the unnecessary operations by skipping all the irrelevant blocks in the search area. The proposed techniques can be incorporated in any block matching motion estimation algorithm. Computational complexity reduction is reflected on the amount of saving in motion estimation encoding time. Simulation results using H.264 reference software (JM 12.4) show up to 71.26% saving in motion estimation time using the proposed techniques compared to the fast full search algorithm adopted in JM 12.4 with a negligible degradation in the PSNR by approximately 0.03 dB and a small increase in the required bits per frame by only 2%.