臺灣博碩士論文加值系統

由於視訊壓縮不斷的推成出新，從早期的H.261、MPEG-1…等到目前最新的視訊標準H.264。在品質與壓縮效能上的要求越來越高，相對的，在計算上的複雜度也因此而越來越複雜。本研究分析了一些目前H.264/AVC在學術領域裡所提出的一些減少複雜度的方式。例如有以Sobel、 Gradient來加速intra mode的決定，也有以分析畫面與畫面之間的temporal correlation，找尋出平滑的區域(Homogeneous region)加速 inter mode的找尋。
其次在Intra/Inter的Mode decision問題上，將以目前的研究中較有效而精確的方法為基礎，此法利用Macroblock之mean removed mean absolute difference (mrMAD)來決定是Intra-mode還是Inter-mode。研究中發現有一些全區域動作(Gloabal motion)或者是快速畫面切換之視訊畫面中，此法會產生一些連續畫面的判定錯誤。因此我們將利用其他參數的特性，比如說動向量的大小，空間域之變異數或時空域之相關性來決定是否會有可能發生連續性判定錯誤的情況。並利用Bayes testing for multiple hypotheses來決定Inter-mode，Intra-mode，或uncertain mode。第二階段再利用更精確的機制來決定uncertain mode之執行，最後假如在無法判斷的部份，就使用完全蒐尋法來做最後的結尾。以此法相信可以在不必增加大量的計算之條件下，改善mode decision方法之精確度。

With the rapid growing of the application in the internet and multimedia environments, the new H.264/AVC video compression standard provides standardized techniques allowing a very compact video data compression. However, due to the complexity of the macroblock prediction, the H.264/AVC video compression standard accounts for a very difficult task for reducing the computational complexity of the mode decision. In this research, we study the current researches for this problem. For an example, some paper utilized the intensity of the Sobel gradient in the spatial domain to determine the intra-mode. In additions, some used the inter-frame correlation to speed up the inter-mode decision.
Next, we will focus on the intra/inter mode decision problem. Based on the current research, an efficient and accuracy algorithm to determine the intra/inter mode was used the mean remove mean absolute difference (mrMAD) as a major parameter to determine the macroblock being the intra-mode or inter-mode. However, from the experiments, we find that this method will lead the wrong decision for the successive frames with the global motion and the fast motion. Thus, we will incorporate more parameters, such as the intensity of the motion vector, variance of the macroblock, or the inter-correlation in the spatial-temporal domain, to refine the mode decision process. In this study, we propose a statistical model based on the Bayes testing for multiple hypotheses to improve the accuracy of the mode decision. In the first stage, we will classify the macroblocks into three catalogs: inter-mode, intra-mode, and uncertain mode. Then, the uncertain mode will be further determined the second stage of the decision process, which may be implemented by full search or included more parameters for the judgment. By this way, we can improve the accuracy of the mode decision method without increasing too much computer complexity.

目錄
誌謝......................................................i
中文摘要.................................................ii
Abstract.................................................iv
目錄.....................................................vi
圖目錄...................................................ix
表目錄..................................................xii
第一章 緒論...............................................1
1.1 研究背景與動機....................................1
1.2 研究目的..........................................3
第二章 視訊壓縮...........................................5
2.1 動態補償之預測編碼................................5
2.1.1 動作向量(motion vector).......................5
2.1.2 動態估測(motion estimation)...................6
2.1.3 動態補償編碼(motion compensation coding)......8
2.2 MPEG-1與MPEG-2....................................9
第三章 H.264/AVC.........................................14
3.1 Introduction.....................................14
3.2 Slice............................................16
3.3 Intra Prediction.................................20
3.4 Inter Prediction............. ...................26
3.4.1 多分割方塊、多參考畫面的預測.................26
3.4.2 Quarter-sample resolution (1/4-pixel)........28
3.5 Rate distortion optimization(RDO)................32
3.6轉換、量化與熵編碼................................33
3.7 相關研究.........................................34
3.7.1 Intra/Inter Mode Decision...................34
3.7.2 Inter Mode Decision.........................35
3.7.3 Intra Mode Decision........................37 第四章 mrMAD-Energy.....................................39
4.1 現有方法.........................................39
4.2 改善機制.........................................47
4.2.1 參數的決定...................................47
4.2.2剩餘巨方塊的進一步判斷........................51
第五章 階層式的編碼模式決定與模擬結果....................56
5.1 階層式的編碼模式決定.............................56
5.2 模擬結果與比較...................................61
第六章 結論..............................................66
參考文獻................................ ................68

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