臺灣博碩士論文加值系統

　　H.264為目前新一代的視訊編碼標準。為了能比先前的標準，如MPEG-1、MPEG-2、MPEG-4、H.261與H.263等，有更佳的影像品質，H.264在編解碼時增加了許多複雜的技術，如：整數離散餘弦轉換、畫面內預測、四分之一像素精度的動作評估、多張參考圖片與多種區塊大小的畫面間預測技術等。雖然能因此達到較好的品質，但同時也使複雜度大幅的提升，進而影響執行效率。而畫面內與畫面間模式決策需要大量地測試各種組態之適應值，是複雜度最高的部分。在H.264中，畫面內模式決策(Intra mode decision)使用了碼率失真計算(Rate-Distortion Optimization, RDO)來找出最佳預測模式，而其運算量是相當高的；對一個宏區塊(Macroblock)來說，找到最佳預測模式就需要做592或736次的碼率失真計算。而為了減少運算量，我們提出了一個簡易的邊界偵測方式來找出一些較合適的預測模式，再利用所提出的適應性模式個數選擇機制來判斷現在的區塊中應選擇幾種預測模式以進行碼率失真計算較佳。經由實驗證明所提出之演算法能在品質與執行效能上取得相當良好的平衡。

　　H.264 is the newest video coding standard. In order to achieve much higher coding efficiency than that of previously published standards, such as MPEG-1/2/4, H.261 and H.263, H.264 codec applies more complicated approaches in the coding procedure, such as integer Discrete Cosine Transformation, intra prediction, quarter-sample-accurate motion estimation, multiple reference frame and variable block-size, in inter prediction mode. Whiling having a better performance, the H.264 comes with the cost of highly increased complexity. Among all the processes, the intra and inter mode decision are the most complex parts in H.264 due to large amount of rate distortion cost have to be calculated for different prediction modes. In H.264, the optimal intra mode is decided based on a highly complex rate-distortion optimization process. For a macroblock, usually a number of 592 or 736 rate-distortion costs have to be calculated before the best prediction mode can be decided. To reduce the complexity, we propose in this paper a simple yet effective edge detection method so that the most probable prediction mode can be found. Moreover, we propose an adaptive algorithm so that a suitable number of prediction modes can be decided for the calculation of rate-distortion optimization inside the macroblock. Experimental results show that a very good trade off between the PSNR, bit-rate and run time performance can be achieved in the proposed approach.

目錄
摘　要 i
ABSTRACT ii
誌 謝 iii
目錄 iv
表目錄 vi
圖目錄 ix
第一章 緒論 1
1.1 研究背景 1
1.2 研究動機 2
1.3 文獻回顧 3
1.4 論文架構 4
第二章 H.264與編解碼軟體介紹 5
2.1 H.264介紹 5
2.1.1 動作評估 7
2.1.2 畫面內模式選擇與預測 9
2.1.3 整數轉換與量化 12
2.1.4 去方塊濾波器 16
2.1.5 熵編碼 20
2.2 編碼軟體介紹 21
第三章 畫面內快速模式決策演算法 23
3.1 相關論文之演算法概述 23
3.1.1. 以Sobel為基底(sobel-based,SB)的快速模式決策 23
3.1.2. Intensity Gradient Technique模式決策(IGT) 27
3.2 邊界偵測演算法 33
3.2.1. 演算法原理 33
3.2.2. Luma4×4與Luma8×8處理流程 35
3.2.3. 適應性模式個數選擇 44
3.2.4. Luma16×16與Chroma8×8處理流程 54
第四章 實驗結果與比較 57
4.1 實驗環境與評估方式 57
4.1.1環境與參數設定 57
4.1.2效能評估方式 58
4.2 實驗結果與比較 62
4.2.1模式選擇數量的影響 62
4.2.2 實驗結果與比較(JM6.1e) 75
4.2.3 實驗結果與比較(JM11.0) 85
4.2.4 實驗結果與比較(JM18.3) 95
參考文獻 104

參考文獻
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