H.264的圖框內型態決策快速演算法

Abstract

我們針對H.264的圖框內決策提出一個快速的新方法來降低編碼器的複雜度。在這個提出的方法中，我們採用了以方向為基礎的特徵偵測來排除可能性較低的4x4預測候選型態。這個方法也藉由一個門檻策略來避免執行不必要的16x16預測型態決策程序。另外，我們也提出了一個較不複雜、可用來評估剩餘代價高低的判斷準則來進一步降低編碼器的複雜度。實驗結果顯示新提出的方法的複雜度比起以SATD為基礎的方法平均減少了百分之五十而壓縮的位元比率和保真度只受到些許的下降。這個方法的另一個變形甚至可以將複雜度降低至百分之四十左右而其位元比率和保真度在可接受的範圍之內。

In this work, we propose a new fast intra mode decision method of H.264/AVC to reduce the encoder complexity. The proposed method incorporates direction-based feature detection to filter out unlikely candidate modes for 4x4 prediction MB type. The method also avoids evoking the unnecessary mode decision process for 16x16 prediction by a threshold strategy. A new low complexity criterion is also incorporated in the method to reduce the encoder complexity further. Experimental results show the complexity is reduced to 50% on average as compared to the widely used SATD-based decision method with only little rate-distortion degradation. Another variation of this method can even reduce the complexity to about 40% with acceptable rate-distortion degradation.