在H.264中，由於在執行移動向量(motion vector)的移動估測(motion estimation)時，需要花費大量的計算時間。因此，H.264中執行移動估測的時候，為了讓畫面可以有更細緻的表現，往往運用了多重參考畫面(multiple reference frame)的技術。然而，由於參考的畫面變多了，所以在計算移動向量時的計算量也會呈倍數的成長。因此，在本篇論文中，我們提出了一個選擇器的演算法來先選取較有可能的最佳參考畫面，再從其中去做移動向量的估測，以達到減少移動估測所需要計算的時間。其後，再透過使用周期的方式，來減少所有區塊模式在做畫面間預測時所需的計算量。本論文提出的演算法在JM14.2上實現並測試H.264編碼的效能測試。根據數組的測試影像，由實驗結果得知與Kuo與Lu所提出的方法比較之下，我們提出的演算法與能在保有不錯的失真率(PSNR)及位元率(bitrate)下，大幅的降低編碼的時間。

In H.264, It requires significant encoding complexity to find motion vector in motion estimation. In motion estimation, H.264 provides some technologies for
increasing precision, i.e. the multiple reference frames technology, variable block size technology and quarter-pixel motion estimation. Unlike other video coding, H.264 can reference more than one reference frame, so it has to pay more computation in motion estimation. In this paper, we proposed an algorithm to select possible frames by the
motion cycle of the object in foreground, and then we will search further in these possible frames. Experimental results show our proposed method is more effective in
encoding time than, and is similar in PSNR and bit rate to the method proposed by
Kuo and Lu.

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