臺灣博碩士論文加值系統

當視訊資料在網路上進行傳輸時，可能會有封包遺失的情形。一旦發生封包遺失，便會造成視訊畫面嚴重失真，特別是高壓縮標準的視訊畫面，其失真程度會更為嚴重；這種失真情形不僅僅是單一畫面的毀損，還可能會連帶波及到後續的畫面。因此，為了改善這種情形，錯誤隱藏技術會用在解碼端來恢復這些遺失的視訊資料。
本論文在H.264/AVC架構下，提出了一套使用邊界失真估測之混合型錯誤隱藏技術。這套技術能藉由適當地轉換時間域和空間域的錯誤隱藏技術來有效恢復損壞的資料，其中的時間域與空間域錯誤隱藏技術皆採用邊界失真估測當作適應性權重切換演算法的評估標準。根據最小的邊界失真程度，對不同的錯誤隱藏技術進行結合，本文的適應性權重切換演算法便能最佳化恢復的效果。因此，基於上述原因，本文的混合型錯誤隱藏技術其效能也勝過其他現存的錯誤隱藏技術，尤其是封包遺失發生在場景變化的畫面或是高動量的區域時，本混合型錯誤隱藏技術其效果的提升將更為顯著。實驗顯示，本論文的混合型錯誤隱藏技術能有效的提升恢復損壞資料的效果。

Packet loss is prone to occurrence in the transmission channel due to error-prone network environments. It usually causes serious distortion, especially in highly compressed video coding standard. The distortion not only damages to single frame but also propagates to successive frames. To improve the distortion, error concealment techniques are adopted to restore lost video data in the decoder.
In this thesis, a hybrid error concealment technique for H.264/AVC based on boundary distortion estimation has been proposed. It could efficiently restore the corrupted data by appropriately switching temporal error concealment approach to spatial error concealment approach. Both of the proposed temporal and spatial error concealment approaches adopt the boundary distortion estimation procedure to be the evaluation criterion. The recovery result with minimal boundary distortion will be selected to restore the corrupted data by the proposed adaptive weight-based switching algorithm. Therefore, the proposed hybrid error concealment technique effectively improves the recovery performance and outperforms other methods, especially packet loss in scene-change frames or high motion regions. Experimental results show the proposed hybrid error concealment technique could effectively enhance the recovery performance.

Chapter 1 Introduction 1
1.1 Motivation 1
1.2 Contributions 3
1.3 Thesis Organization 4

Chapter 2 Background and Related Works 5
2.1 Background 5
2.1.1 The Slice Structuring in H.264 Encoder 5
2.1.2 The Error Concealment in H.264 Decoder 6
2.1.3 The GOP Structure 7
2.1.4 Error Propagation 8
2.2 Related Works 9
2.2.1 Qian et al. method 10
2.2.2 Cui et al. Method 11
2.2.3 Zhan and Zhu Method 13
2.2.4 Wang et al. Method 14

Chapter 3 The Proposed Hybrid Error Concealment in H.264/AVC 17
3.1 The Proposed Temporal Error Concealment 18
3.1.1 Searching for the Most Similar MB by Mean Absolute Difference (MAD) 20
3.1.2 Calculation of the Boundary Residual 21
3.1.3 Adopting the Proposed Bi-linearity Interpolation Filter and Enhancement 22
3.1.4 Calculation of the Proposed Temporal Evaluation Criterion 23
3.1.5 Calculation of the Standard Deviation 24
3.1.6 Applying the Proposed Adaptive Weight-based Switching Algorithm 25
3.1.7 Applying the Proposed Texture-based Selective Calibration Technique 26
3.2 The Measure of Temporal and Spatial Activity 27
3.3 The Proposed Spatial Error Concealment 29
3.3.1 Edge Detection Filter 31
3.3.2 Determining the Dominant Edge Points 32
3.3.3 Applying the Selective Directional Interpolation 33
3.3.4 Applying the Multi-directional Interpolation 35
3.3.5 Applying the Bilinear Interpolation 36
3.3.6 Integration of Various Interpolation Modes 38
3.3.7 Calculation of the Proposed Spatial Evaluation Criterion 38
3.3.8 Applying the Proposed Adaptive Weight-based Switching Directional Interpolation 40

Chapter 4 Experimental Results 41
4.1 Experimental Environment 41
4.2 Comparison of PSNR with Other Methods 43
4.3 Comparison of Subjective Quality 49
4.4 The Percentage of Temporal-based and Spatial-based Error Concealment 56

Chapter 5 Conclusions 59

References 61

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