高效能視訊編碼之標準制訂與運算平行化(I)

Abstract

本報告提出一項單一區塊之多重動作向量預估模式，其同時應用模塊樣板匹配 (Template Matching)與區塊動作補償 (Block Motion Compensation)兩種估測技術，輔以交疊區塊動作補償(Overlapped Block Motion Compensation)技術有效地結合兩種估測技術。透過模塊樣板匹配之動作向量可在解碼端動態產生且不須耗費頻寬傳遞之特性，本技術只需傳遞單一動作向量，搭配模塊樣板匹配之動作向量，即達到近乎與傳統?動作向量估測相似的估測效能。透過兩種不同信號模型的驗證，模塊樣板匹配之動作向量趨近於模塊樣板重心點之運動向量。基於此，區塊動作向量搜尋的結果必需能補償模塊樣板匹配估測效能不足之處；在我們的理論上，區塊動作向量搜尋可視為在區塊(子)像素間挑出一者，以其動作向量為最佳選擇套用至整個區塊上。此外，本文以實驗討論壓縮效率與編解碼效率間的權衡，包含多模塊樣板類型之測試、多動作向量預估模式、與簡化模塊樣板匹配之設計。於HM-3.0軟體平台大量測試的結果證實了本文方法之效率與可行性。

This report introduces a multi-hypothesis temporal prediction technique that combines two motion vectors (MVs) derived respectively from template and block matching for overlapped block motion compensation (OBMC). It achieves similar prediction performance to bi-prediction while only one MV has to be sent. Based on two signal models, the template MV is shown to approximate the pixel true motion around the template centroid. We then find another MV to best complement the template MV from both deterministic and statistical viewpoints, the latter leading to the search of its optimal sampling location in the motion field. The result is a search criterion with OBMC window functions forming a geometry-like motion partitioning. To compromise between performance and complexity, generalizations to adaptive template design, multi-hypothesis prediction and motion merging are made. Extensive experiments conducted with the HM-3.0 software confirm the effectiveness of the proposed schemes.