發(fā)布時(shí)間：2018-08-28 17:41

【摘要】：新一代視頻編碼標(biāo)準(zhǔn)HEVC作為H.264/AVC的繼承者,在視頻壓縮效率方面取得了巨大的提升,相比于H.264/AVC,HEVC在相似的視頻感知質(zhì)量下比特率減少了大約50%,因此正在逐漸成為業(yè)界視頻壓縮的主流標(biāo)準(zhǔn)。同時(shí)隨著移動(dòng)互聯(lián)網(wǎng)革命的爆發(fā),人們?cè)絹?lái)越頻繁地使用移動(dòng)端設(shè)備來(lái)觀看視頻,而在移動(dòng)網(wǎng)絡(luò)中視頻的瀏覽受到網(wǎng)絡(luò)阻塞的影響十分明顯,暫時(shí)的網(wǎng)絡(luò)阻塞會(huì)大大降低用戶的觀看體驗(yàn)。因此在視頻服務(wù)器端,往往會(huì)保存視頻的高比特率版本,并根據(jù)當(dāng)前網(wǎng)絡(luò)情況實(shí)時(shí)轉(zhuǎn)碼為不同碼率的視頻流提供給用戶。這種情況就對(duì)高清HEVC視頻的轉(zhuǎn)碼速度提出了新的要求。視頻轉(zhuǎn)碼實(shí)際上是一個(gè)先解碼再編碼的過(guò)程,其中編碼部分耗時(shí)占比達(dá)到90%。而HEVC標(biāo)準(zhǔn)因?yàn)槠涮厥庑?編碼時(shí)需要確定最優(yōu)CU劃分模式,這個(gè)過(guò)程需要遍歷每一層CU劃分,同時(shí)還需要進(jìn)行復(fù)雜的率失真優(yōu)化(RDO)計(jì)算,因此這是一個(gè)十分耗時(shí)的過(guò)程。針對(duì)這個(gè)問(wèn)題,本文提出了兩種快速確定編碼單元CU劃分模式的算法來(lái)降低HEVC標(biāo)準(zhǔn)視頻的轉(zhuǎn)碼計(jì)算復(fù)雜度,從而在基本不影響視頻質(zhì)量的前提下,大大縮短視頻轉(zhuǎn)碼時(shí)間。第一種方法利用了輸入的高比特率視頻流與輸出的低比特率視頻流在深度值上的關(guān)聯(lián)性,簡(jiǎn)單快速地確定出深度值范圍,從而減少CU劃分模式的遍歷范圍。通過(guò)實(shí)驗(yàn)證明,相比于傳統(tǒng)的全解全編轉(zhuǎn)碼模式,此方法僅僅增加了 0.84%的比特率,而轉(zhuǎn)碼時(shí)間縮短了 54%。第二種方法結(jié)合機(jī)器學(xué)習(xí)理論提出了在線訓(xùn)練在線分類(lèi)的轉(zhuǎn)碼框架,利用原始碼流CU劃分信息以及時(shí)域前一幀的CU劃分信息,通過(guò)樸素貝葉斯分類(lèi)器預(yù)測(cè)出編碼端的CU劃分標(biāo)志,從而確定了 CU劃分模式。實(shí)驗(yàn)表明,通過(guò)這種方法視頻實(shí)驗(yàn)幀僅僅增加了 2.74%的比特率,而轉(zhuǎn)碼時(shí)間縮短了 72%左右。
[Abstract]:As the successor of H.264/AVC, HEVC, a new video coding standard, has made great progress in video compression efficiency. Compared with H.264 / AVC HEVC, the bit rate is reduced by about 50% under the similar video perception quality, so it is becoming the mainstream standard of video compression in the industry. At the same time, with the outbreak of the revolution of the mobile Internet, people use mobile devices more and more frequently to watch video. However, in the mobile network, the browsing of video is obviously affected by the blocking of the network. Temporary network congestion can greatly reduce the user's viewing experience. Therefore, in the video server, the high bit-rate version of the video is often saved, and real-time transcoding is provided to the user for different bit-rate video streams according to the current network conditions. This situation puts forward new requirements for high-definition HEVC video transcoding speed. Video transcoding is actually a process of decoding and coding, in which the coding part takes up 90% of the time. Because of its particularity, HEVC standard needs to determine the optimal CU partitioning mode, which needs to traverse every layer of CU partition and perform complex rate-distortion optimization (RDO) computation, so it is a very time-consuming process. To solve this problem, this paper proposes two fast algorithms to determine the CU partition mode of the coding unit to reduce the computational complexity of the transcoding of the HEVC standard video, thus greatly reducing the transcoding time without affecting the video quality. The first method makes use of the correlation between the input high bit rate video stream and the output low bit rate video stream on the depth value, and determines the range of the depth value simply and quickly, thus reducing the traversal range of the CU partition mode. It is proved by experiments that compared with the traditional fully decomposed full-coding mode, the proposed method can only increase the bit rate by 0.84% and shorten the transcoding time by 54%. The second method combines machine learning theory and puts forward the transcoding framework of online training online classification, which uses the CU partition information of the original code stream and the CU partition information of the previous frame in the time domain. By using naive Bayesian classifier to predict the CU partition flag in the coding end, the CU partition mode is determined. The experimental results show that the proposed method can only increase the bit rate by 2.74% and shorten the transcoding time by about 72%.
【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】：2017
【分類(lèi)號(hào)】：TN919.81

【參考文獻(xiàn)】

相關(guān)期刊論文 前8條

1 李雪晴;何小海;吳小強(qiáng);林宏偉;;結(jié)合模式對(duì)應(yīng)與機(jī)器學(xué)習(xí)的HEVC降分辨率轉(zhuǎn)碼[J];電視技術(shù);2016年01期

2 程悅;賈克斌;呂卓逸;;一種基于快速模式選擇的H.264跳幀轉(zhuǎn)碼算法的研究[J];計(jì)算機(jī)應(yīng)用與軟件;2015年03期

3 胡乾乾;沈禮權(quán);趙振軍;;基于場(chǎng)景切換的HEVC碼率控制算法[J];電視技術(shù);2015年05期

4 劉昱;胡曉爽;段繼忠;;新一代視頻編碼技術(shù)HEVC算法分析及比較[J];電視技術(shù);2012年20期

5 楊高波;夏中超;張兆揚(yáng);王會(huì)千;;一種基于線性回歸模型的運(yùn)動(dòng)矢量重估算法[J];湖南大學(xué)學(xué)報(bào)(自然科學(xué)版);2010年07期

6 郭亞寧;馮莎莎;;機(jī)器學(xué)習(xí)理論研究[J];中國(guó)科技信息;2010年14期

7 張亞娜;張琦;;碼率控制中的率失真優(yōu)化[J];中國(guó)傳媒大學(xué)學(xué)報(bào)(自然科學(xué)版);2006年01期

8 程愷英,王宏遠(yuǎn),樊淳標(biāo);數(shù)字視頻轉(zhuǎn)碼技術(shù)綜述[J];電視技術(shù);2005年04期

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