移動預估在視訊壓縮編碼上一直扮演著重要的角色，其最主要的目的，是利用畫面間的相關性，來移除多餘的資料量，以達到壓縮目的。因此移動預估演算法的好壞，對整個視訊壓縮品質有極大的影響。 過去的移動向量預估僅僅考慮前一個延遲時間的畫面，而多幅移動向量預估則允許使用不同數目的參考畫面。多幅移動向量預估系統同時在編碼端及解碼端儲存之前數張的影像，能夠更有效率的對影像進行編碼。在新一代的視訊標準H.264中，允許五張的參考影像，有效的降低位元率，並提高編碼效能。然而，電腦運算量卻也同時劇烈的上升。單幅移動向量預估領域已經累積了為數可觀的研究與討論，我們從過去的論文可以知道好的初始值將可以改善快速演算法的收斂速度，獲得更好的運算效能。我們所提出的方法乃是針對多幅移動向量預估的特性，發展出更精確的向量預測，以提供更佳的初始值。此外，針對四分之一像素的模型分析，我們也加以發展適當的快速搜尋演算法。 Motion estimation plays an extremely important role in the video coding. The objective of the motion estimation is to remove the temporal redundancy between video frames so that the motion compensated frames can be coded efficiently. Multi-frame motion-compensated prediction extends the spatial displacement vector utilized in blocking-based hybrid video coding by a variable frame reference permitting the use of more frames than the previously decoded one for motion-compensated prediction. The multi-frame buffer stores frames at encoder and decoder that efficient for motion-compensated prediction. The use of multiple frames for motion compensation in most cases provides significantly improved coding gain. The multiple reference picture selection in H.264 allows the encoder store up to five previous frames for motion estimation. However, the complexity will increase five times dramatically. Numerous fast search algorithms in single-frame motion estimation are proposed in the past. As we know, a good initial point can speed up the velocity of fast search algorithm. Our proposed algorithm is focus on multi-frame condition, and provides more precisely prediction as initial point.
