臺灣博碩士論文加值系統

新一代高效率視訊編碼 (HEVC) 具有35種畫面內預測模式和不同大小的編碼單元，提高了編碼效率。與H.264/AVC相比，在相同的重建視訊的畫面品質下，節省50%的位元率，但也提高了編碼的複雜度，導致編碼時間增加。
本論文提出一種基於梯度的快速編碼單元 (CU) 分割及畫面內預測快速模式決策的演算法。在編碼單元分割的部分，根據相鄰編碼單元之間的空間相關係跳過大型編碼單元的運算，再透過紋理複雜度決定編碼單元起始分割的深度；在畫面內預測，透過紋理找出接近的角度模式，減少進入RDO的候選模式數量，結合兩種方法，達到節省編碼時間的目的。
實驗結果顯示，我們提出的方法與 HEVC 參考軟體 HM16.20 的方法相比，編碼時間平均節省55.79%，且平均位元率增加4.40%，以及平均0.22dB的重建視訊畫面品質損失。

The High Efficiency Video Coding (HEVC) has 35 intra-frame prediction modes and utilizes the variable-sized coding-units (CUs) to improve the coding efficiency. Compared with H.264/AVC, HEVC reduces the bit rate by about 50% at almost the same quality of reconstructed video, but it also increases the computational complexity of encoding, resulting in increased encoding time.
This paper proposes an algorithm combining a gradient-based fast coding unit partition and a fast prediction mode decision for intra coding to achieve the encoding time saved. According to the spatial correlation between the adjacent coding units, the operations of the larger coding units is skipped, and then the initial depth of the coding tree units is determined by using the texture complexity within the coding unit. In the intra-frame prediction, the angular prediction modes are found through approaching to the texture direction within the prediction unit (PU), and it reduces the number of candidate modes of the rate-distortion optimization (RDO) procedure. The two methods are combined to effect the coding time saved more.
The experimental results show that, compared with the algorithm of the HEVC reference software HM16.20, our proposed method can save the encoding time on average by 55.79% with the Bjontegaard delta bit-rate (BD-BR) of 4.40% increasing on average and the Bjontegaard delta peak-signal-to-noise ratio (BD-PSNR) of 0.22dB quality loss of reconstructed video on average.

摘要............i
ABSTRACT............ii
誌謝............iv
目錄............v
英文簡寫說明............vi
中英文對照表............ix
圖目錄............xiii
表目錄............xv
第一章 緒論............1
1.1 研究背景............1
1.2 研究動機與目的............2
1.3 論文架構............4
第二章 HEVC視訊編碼標準介紹............5
2.1 HEVC視訊編碼概述............5
2.2 HEVC視訊編碼架構............10
2.3 四元樹分割法 (Quad-tree Structure)............16
2.3.1 編碼單元 (Coding Unit, CU)............17
2.3.2 預測單元 (Prediction Unit, PU)............19
2.3.3 轉換單元 (Transform Unit, TU)............21
2.4 階層編碼結構............22
2.5 畫面內預測編碼............25
第三章 我們提出的方法............29
3.1 HEVC遭遇的問題............29
3.2 畫面內預測之快速編碼單元分割及快速模式決策相關文獻探討............29
3.3 Wang等[3]的畫面內預測之快速編碼單元分割的方法............31
3.4 Yang等[4]的畫面內預測之快速模式決策............38
3.5 我們所提出的方法............41
第四章 實驗模擬與效能比較............46
4.1 緒論............46
4.2 實驗環境............46
4.3 測試視訊序列............46
4.4 實驗結果............58
4.5 效能比較............75
第五章 結論............90
參考文獻............91

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[14]HM, HEVC Test Model, Available:
https://hevc.hhi.fraunhofer.de/svn/svn_HEVCSoftware/tags/
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