HEVC畫面內預測之快速模式決策及基於均勻性之編碼單元分割提早終止演算法

魏清煌 ； 李榮家

《TANET2019 臺灣網際網路研討會》 2019年 (2019/12) Pp. 51-56

https://doi.org/10.6924/TANET.201909.0009

摘要

目前最新的視訊壓縮標準為高效率視訊編碼（HEVC），它是以H.264/AVC為主要架構，但與H.264/AVC不同的是，HEVC在相似的重建視訊品質下，壓縮效率可以提升一倍，也就是節省50%的位元率，但卻需要付出更多的編碼時間。本論文提出一種快速編碼單元分割演算法及畫面內預測模式快速決策的方法，利用判斷編碼單元中是否有均勻區塊的特性，來提前終止均勻的編碼單元分割，及減少與篩選畫面內預測的候選模式，來節省更多編碼時間。實驗結果顯示，與HEVC參考軟體HM16.20相比，我們所提出的方法，平均可以節省47.799%的編碼時間，且僅有平均2.186％的編碼位元率增加，以及平均0.116dB的重建視訊畫面品質損失。

關鍵字

HEVC ； 畫面內預測 ； 編碼單元分割 ； 提早終止 ； 模式決策

並列摘要

As the latest video compress ion standard, the high efficiency video coding (HEVC) has the coding and decoding architecture similar to H.264/AVC. Compared with H.264/AVC, HEVC can improve the compression efficiency in saving 50% bit rate with the similar quality of reconstructed video but pay the penalty of higher computational complexity and more encoding time. This paper proposes a fast mode decision and early termination of coding-unit partitioning algorithm for the intra - frame prediction in HEVC. It is to determine whether the coding unit is a uniform block based on the sum of maximal absolute difference in the coding unit compared with a pre -defined threshold to terminate the uniform coding unit partition in advance. To reduce the encoding time more, a two-phase rough intra-prediction mode decision (RMD) algorithm is utilized to select three intra -predict ion modes into the candidate list. Finally, there are 3 to 6 candidate modes will be conducted by the high-precision rate -distortion optimization (RDO) calculation and the mode with the least rate -distortion cost as the optimal intra -predict ion mode will be selected. The experimental results show that compared with the HEVC reference software HM16.20, the proposed method can save an aver age of 47.799% of encoding time with only 2.186% Bjontegaard delta bit - rate (BD-BR) increasing and 0.116dB Bjontegaard delta peak- signal -to-noise ratio (BD-PSNR) degradation of reconstructed video.

並列關鍵字

HEVC ； Intra prediction ； Coding-unit partition ； Early termination ； Mode decision