基于HEVC幀內(nèi)預(yù)測(cè)算法的優(yōu)化
發(fā)布時(shí)間:2018-06-27 05:48
本文選題:HEVC + 幀內(nèi)預(yù)測(cè); 參考:《南京理工大學(xué)》2014年碩士論文
【摘要】:高效率視頻編碼標(biāo)準(zhǔn)(HEVC,High Efficiency Video Coding)于2010年由JCT-VC制定,并于2013年正式發(fā)布。相比較上一代視頻壓縮標(biāo)準(zhǔn)H.264/AVC,在相同圖像質(zhì)量下HEVC能節(jié)省50%的碼率,但是計(jì)算復(fù)雜度卻大幅提高了。因此如何降低HEVC視頻編碼算法的計(jì)算復(fù)雜度,提高編碼的時(shí)效性成為了當(dāng)前研究的熱點(diǎn)。鑒于此,本文重點(diǎn)研究了幀內(nèi)編碼算法及其優(yōu)化方法,主要工作及成果如下: 1)針對(duì)最大編碼單元(LCU, Largest Coding Unit)中,編碼塊劃分次數(shù)過(guò)多導(dǎo)致的高計(jì)算復(fù)雜度問(wèn)題,本文提出了一種提前終止編碼塊劃分的優(yōu)化算法。該算法首先利用圖像的紋理特性,分析了不同深度下相鄰編碼塊劃分的相關(guān)性;然后提出了提前終止編碼塊劃分的方案:即利用左側(cè)、上方、左上方已編碼塊的劃分信息,來(lái)決定右下方編碼塊是否需要?jiǎng)澐帧?shí)驗(yàn)表明:本文提出的算法與原始算法相比較,碼率增加了約1.02%,峰值信噪比下降了約0.045dB,編碼時(shí)間縮短了近17.79%。 2)本文在研究了幀內(nèi)預(yù)測(cè)中模式選擇算法的基礎(chǔ)上,提出了一種快速預(yù)測(cè)模式選擇的優(yōu)化算法。該算法將粗略模式選擇(RMD, Rough Mode Decision)過(guò)程,分成初篩選和再篩選兩步,以此減少了RMD模式的個(gè)數(shù);然后利用最有可能模式(MPM, Most Probable Mode)和第一個(gè)候選模式的相關(guān)性,提出了優(yōu)先選取最佳預(yù)測(cè)模式的方案;最后對(duì)候選模式進(jìn)行分組,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)。實(shí)驗(yàn)表明:本文提出的算法與原始算法相比較,碼率增加了約0.04%,峰值信噪比下降了約0.034dB,編碼時(shí)間縮短了近25.1%。 最后本文將以上兩種算法合并成了一個(gè)新的優(yōu)化算法。新算法相比較HEVC原始算法,碼率增加了約1.08%,峰值信噪比下降了約0.075dB,編碼時(shí)間減少了近37.16%。
[Abstract]:The HEV C High efficiency Video coding standard was developed by JCT-VC in 2010 and released in 2013. Compared with the previous video compression standard H.264 / AVC, HEVC can save 50% bit rate under the same image quality, but the computational complexity is greatly increased. Therefore, how to reduce the computational complexity of HEVC video coding algorithm and improve the timeliness of coding has become a hot topic. In view of this, this paper focuses on the intra coding algorithm and its optimization method. The main work and results are as follows: 1) in order to solve the problem of high computational complexity caused by the excessive number of coding blocks in LCU (Largest coding Unit), In this paper, an optimization algorithm for preemptive termination of block partition is proposed. The algorithm firstly analyzes the correlation between adjacent coding blocks at different depths by using the texture characteristics of the image, and then puts forward a scheme to terminate the partition of coding blocks in advance, that is, using the partition information of the coded blocks on the left, the top and the upper left. To determine whether the lower right coding block needs to be partitioned. Experimental results show that compared with the original algorithm, the proposed algorithm increases the bit rate by about 1.02db, decreases the PSNR by 0.045dB, and shortens the coding time by nearly 17.79dB. 2) based on the study of the mode selection algorithm in intra prediction, An optimization algorithm for fast prediction mode selection is proposed. The algorithm reduces the number of RMD modes by dividing the rough Mode decision process into two steps: initial filtering and re-filtering, and then takes advantage of the correlation between MPM (most enable Mode) and the first candidate mode. The optimal prediction mode is selected first and the candidate modes are grouped to reduce the number of modes of participating rate-distortion cost calculation adaptively. Experimental results show that compared with the original algorithm, the proposed algorithm increases the bit rate by about 0.04, decreases the PSNR by about 0.034dB, and shortens the coding time by about 25.1dB. Finally, the above two algorithms are combined into a new optimization algorithm. Compared with the original HEVC algorithm, the new algorithm increases the bit rate by about 1.08, decreases the peak signal-to-noise ratio (PSNR) by 0.075 dB, and reduces the coding time by about 37.16dB.
【學(xué)位授予單位】:南京理工大學(xué)
【學(xué)位級(jí)別】:碩士
【學(xué)位授予年份】:2014
【分類(lèi)號(hào)】:TN919.81
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