本文選題：HEVC　切入點(diǎn)：幀內(nèi)預(yù)測(cè)　出處：《西安電子科技大學(xué)》2014年碩士論文

【摘要】：HEVC(High Efficiency Video Coding)是繼H.264/AVC之后的新一代視頻編碼標(biāo)準(zhǔn),由協(xié)作視頻編碼組JCT-VC聯(lián)合制定。HEVC保留了基于塊運(yùn)動(dòng)補(bǔ)償?shù)膫鹘y(tǒng)混合視頻編碼框架,同時(shí)在幀內(nèi)預(yù)測(cè)、幀間預(yù)測(cè)、正交變換與量化、熵編碼等關(guān)鍵模塊部分都采用了相應(yīng)的新技術(shù),使得HEVC在基本保證H.264/AVC所有的功能與應(yīng)用的情況下,其編碼效率有了顯著提升,相較于H.264/AVC提高了一倍。HEVC優(yōu)異的編碼性能是以較大的編碼復(fù)雜度為代價(jià)實(shí)現(xiàn)的,比如四叉樹(shù)遞歸塊劃分結(jié)構(gòu)、率失真優(yōu)化決策、35種幀內(nèi)預(yù)測(cè)方向等關(guān)鍵技術(shù)的復(fù)雜度都非常高。本文對(duì)HEVC幀內(nèi)編碼進(jìn)行了深入研究,降低幀內(nèi)編碼復(fù)雜度,提高整體編碼效率。針對(duì)幀內(nèi)預(yù)測(cè)過(guò)程中的模式選擇及影響模式選擇性能的相關(guān)部分,從幀內(nèi)分塊的四叉樹(shù)遍歷結(jié)構(gòu)和幀內(nèi)預(yù)測(cè)模式的選擇過(guò)程兩方面進(jìn)行了深入分析,并對(duì)幀內(nèi)預(yù)測(cè)各部分的計(jì)算量進(jìn)行了統(tǒng)計(jì)。對(duì)于LCU其幀內(nèi)編碼存在的可能劃分方式有1024種,幀內(nèi)預(yù)測(cè)多達(dá)35個(gè),對(duì)35種模式都要進(jìn)行率失真優(yōu)化決策,由此導(dǎo)致幀內(nèi)預(yù)測(cè)運(yùn)算量非常龐大。本文針對(duì)HEVC幀內(nèi)預(yù)測(cè)瓶頸問(wèn)題,提出了一種基于三步快速選擇的HEVC幀內(nèi)預(yù)測(cè)優(yōu)化算法。幀內(nèi)預(yù)測(cè)最佳模式選擇需兩個(gè)基本步驟:粗略模式選擇(RMD過(guò)程)和模式細(xì)選(RDO過(guò)程)。針對(duì)兩個(gè)過(guò)程分別進(jìn)行詳細(xì)分析,提出了相應(yīng)的優(yōu)化算法主要策略如下:(1)基于三步選擇的粗選優(yōu)化算法。本算法在模式粗略選擇(RMD,Rough Mode Decision)過(guò)程中優(yōu)先搜索預(yù)設(shè)大方向、再在選定大方向范圍內(nèi)精確搜索兩步,使得原需遍歷多達(dá)35種幀內(nèi)預(yù)測(cè)模式,減少到最多遍歷15種模式即能得出最佳預(yù)測(cè)模式,以此減少了一半的需計(jì)算SATD代價(jià)的模式個(gè)數(shù);(2)基于視頻特性的細(xì)選優(yōu)化算法。本算法利用最有可能模式(MPM,Most Probable Mode)和第一個(gè)候選模式的相關(guān)性,提出了最佳預(yù)測(cè)模式選擇的最后一步,根據(jù)PU尺寸的大小自適應(yīng)地減少了參與率失真代價(jià)計(jì)算的模式個(gè)數(shù),有效減少細(xì)選計(jì)算量。為驗(yàn)證上述三步快速選擇算法的效率,本文選擇HEVC標(biāo)準(zhǔn)測(cè)試序列對(duì)其進(jìn)行了系統(tǒng)的測(cè)試。本文提出的優(yōu)化算法與標(biāo)準(zhǔn)算法相比較,實(shí)驗(yàn)結(jié)果顯示:在不同序列、不同QP參數(shù)的配置情況下,本算法保證視頻質(zhì)量基本不變,碼率稍有增加,平均在0.2%左右;亮度峰值信噪比PSNR的降低量均在0.05d B左右,保證在0.1dB之內(nèi);而編碼時(shí)間平均減少了約40%,很大程度上加快了編碼速度。實(shí)驗(yàn)結(jié)果可以充分表明,本文實(shí)現(xiàn)的算法能夠有效的提高編碼效率、縮短幀內(nèi)編碼時(shí)間,對(duì)HEVC的實(shí)際應(yīng)用具有積極的意義。
[Abstract]:HEVC(High Efficiency Video coding is a new generation video coding standard after H.264/AVC. It is developed by cooperative video coding group (JCT-VC). It preserves the traditional hybrid video coding framework based on block motion compensation, and at the same time, it is used in intra-frame prediction, inter-frame prediction, quadrature transform and quantization. Some key modules, such as entropy coding, have adopted the corresponding new technology, which makes the coding efficiency of HEVC improve significantly when all functions and applications of H.264/AVC are basically guaranteed. Compared with H.264/AVC, the excellent coding performance of HEVC is achieved at the cost of large coding complexity, such as quadtree recursive block partition structure. The complexity of the key techniques such as rate-distortion optimization decision and 35 kinds of intra prediction directions are very high. In this paper, the intra coding of HEVC is studied in depth to reduce the intra coding complexity. In order to improve the overall coding efficiency, the mode selection in the intra prediction process and the related parts that affect the performance of the mode selection are analyzed in detail from two aspects: the quadtree traversal structure of the intra block and the selection process of the intra prediction mode. For LCU, there are 1024 possible partition modes, 35 intra prediction modes, and rate-distortion optimization decision for all 35 modes. As a result, the intra prediction computation is very large. This paper aims at the bottleneck problem of intra prediction in HEVC. This paper presents an algorithm for intra-frame prediction optimization of HEVC based on three-step fast selection. It requires two basic steps: rough mode selection (rough mode selection) and mode selection process (RDO). The two processes are analyzed in detail. The main strategy of the corresponding optimization algorithm is as follows: 1) rough selection algorithm based on three-step selection. In the process of rough pattern selection, the algorithm gives priority to searching for the default direction, and then accurately searches two steps within the selected broad direction. This makes it possible to traverse as many as 35 intra prediction modes, so that the best prediction mode can be obtained by reducing the traversal to up to 15 modes. In this way, the number of modes needed to calculate the cost of SATD is reduced by half.) the algorithm is based on video features. This algorithm utilizes the correlation between the most probable mode and the first candidate mode. The last step of optimal prediction mode selection is proposed. According to the size of pu, the number of modes calculated by participating rate-distortion cost can be reduced adaptively, and the computation of fine selection can be effectively reduced. In order to verify the efficiency of the three-step fast selection algorithm mentioned above, In this paper, the HEVC standard test sequence is selected to test it systematically. Compared with the standard algorithm, the experimental results show that: under different sequences and different QP parameters configuration, The algorithm ensures that the video quality is basically unchanged, the bit rate is slightly increased, the average is about 0.2%, and the decrease of PSNR is about 0.05 dB, which is within the 0.1dB. However, the average coding time is reduced by about 40 percent, which greatly accelerates the coding speed. The experimental results show that the proposed algorithm can effectively improve the coding efficiency and shorten the coding time within frames. It is of positive significance to the practical application of HEVC.
【學(xué)位授予單位】：西安電子科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TN919.81

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 趙文強(qiáng);沈禮權(quán);張兆楊;;HEVC幀內(nèi)預(yù)測(cè)算法的優(yōu)化[J];電視技術(shù);2012年08期

相關(guān)碩士學(xué)位論文 前1條

1 李樂(lè);針對(duì)HEVC視頻編碼標(biāo)準(zhǔn)的幀間快速算法研究[D];華中科技大學(xué);2013年

，

本文編號(hào)：1668223