A Study on Fast Intra-Prediction Mode Decision Method based on Block Correlation for H.264/AVC

在論文中，針對H.264/AVC中圖框內空間性預測編碼，新提出一個快速模式決策演算法。為了加速找出給目標區塊適當的預測模式，我們利用目標區塊與其相臨的幾個區塊之相依性，來減少編碼過程中的計算複雜度；相臨的區塊包含幾個在空間上相依靠的區塊，和在時間上前一個圖框中相同位置的區塊。在演算法中，也利用了一種更新策略，在只增加一些計算的複雜度下增強視訊的品質。比較已存在JM的SATD模式決策演算法，這裡提議的演算法，在可接受的速度失真損失表現下，可以平均減少圖框內4x4編碼的運算複雜度到40%。In this thesis, we propose a new fast mode decision method for intra-only H.264/AVC video coding. To speed up determining the optimal prediction mode for an intra-coded target block, we exploit the correlation between the target block and a set of adjacent blocks to reduce the computational complexity of the encoding process. The set of adjacent blocks consists of several spatial neighboring blocks in the same frame and one block in a previous frame positioned at the same spatial location as the target block. The method also utilizes a refreshing strategy not relying on correlation to enhance the video quality with little increase in computational complexity. Compared to the SATD-based (sum of absolute transformed differences) full mode decision algorithm used in the encoding model of H.264 (JM9.3), the proposed algorithm can reduce the computational complexity of intra coding by 40% on average with acceptable loss of rate-distortion performance.口試委員會審定書 i 誌謝 ii 中文摘要 iii Abstract iv Chapter 1 Introduction 2 Chapter 2 H.264/AVC Overview 5 2.1. I-slice 8 2.1.1. Intra Spatial Prediction………………………………………………8 2.1.2. Transform and Quantization………………………………………10 2.1.3. Scanning……………………………………………………………12 2.1.4. Entropy coding……………………………………………………..13 2.1.5.1. UVLC coding……………………………………………….14 2.1.4.2. CAVLC coding……………………………………………..16 2.1.4.3. CABAC……………………………………………………..17 2.2. P-slices 18 2.5. Deblocking Filter 22 2.6. Error Resilience Tools 22 2.7. The Baseline, Main, and Extended Profiles in the First Version 23 2.8 The New High Profiles Defined in the FRExt Amendment 25 2.9. Levels 26 Chapter 3 Issues Related to H.264/AVC Intra Coding 29 3.1 The Performance of H.264/AVC Intra Prediction Coding 29 3.2 Intra-only Profiles for Professional Applications 30 3.3 Problems Related to Multiple Mode Decision 31 3.4 Computation Cost of Intra Prediction Modes 35 Chapter 4 Proposed Scheme 39 4.1 Basic idea I: Correlation of Modes 39 4.2 Basic idea II: Periodical Full Mode Selection 43 4.3 Summary of the Proposed Intra4x4 Mode Decision Process 45 Chapter 5 Experiment results 47 5.1 Experiment Conditions 47 5.2 Simulation Results 47 Chapter 6 Conclusions and Future Work 62 6.1 Conclusions 62 6.2 Future Work 63 Reference 6