本文選題：率失真優(yōu)化 + 模式判決��； 參考：《西安電子科技大學(xué)》2014年博士論文

【摘要】：多媒體業(yè)務(wù)的快速發(fā)展和用戶對(duì)視頻質(zhì)量需求的不斷提升，促使了視頻編碼技術(shù)不斷地改進(jìn)和更新。目前視頻編碼標(biāo)準(zhǔn)H.264/AVC憑借其高的編碼性能已廣泛滲透到各種媒體產(chǎn)品中。然而由于具有更好的用戶體驗(yàn)，超高清視頻業(yè)務(wù)逐步走入人們視野，但其龐大的數(shù)據(jù)量使得存儲(chǔ)和傳輸面臨嚴(yán)峻的考驗(yàn)。為此視頻編碼聯(lián)合小組JCTVC制定了下一代視頻編碼標(biāo)準(zhǔn)H.265/HEVC，以進(jìn)一步提高視頻壓縮效率。 在視頻編碼中，率失真優(yōu)化技術(shù)扮演著關(guān)鍵的角色。它指導(dǎo)著編碼器中模式判決和碼率控制這兩個(gè)重要模塊的運(yùn)行，以保證編碼模式的選擇、碼率的分配和量化參數(shù)的確定更加地合理高效。因此本文重點(diǎn)研究了基于率失真優(yōu)化的H.264/AVC、H.265/HEVC模式判決模塊，以及H.265/HEVC碼率控制模塊。此外本文還研究了有關(guān)質(zhì)量測(cè)度的模型。主要研究成果包括： 1.針對(duì)H.264/AVC中模式判決的高復(fù)雜度問(wèn)題，提出一種快速碼率估計(jì)算法。本文首先分析了上下文自適應(yīng)二元算法編碼（CABAC）的基本原理，以及殘差塊所涉及的各個(gè)語(yǔ)法元素特性�；谶@種分析，提出一種有效的殘差碼率估計(jì)算法，用于代替模式判決中的實(shí)際CABAC編碼。一方面，本文所提算法可以準(zhǔn)確地估計(jì)殘差塊的編碼碼率。另一方面，其設(shè)計(jì)適于硬件的并行運(yùn)算，可以進(jìn)一步節(jié)省編碼時(shí)間。實(shí)驗(yàn)結(jié)果表明，H.264/AVC模式判決中的CABAC編碼復(fù)雜度可降低約57%，而視頻質(zhì)量幾乎不受影響。 2.針對(duì)H.265/HEVC的編碼復(fù)雜度問(wèn)題，提出一種新的快速模式判決算法�？紤]到視頻幀的紋理特性和其編碼中所采用的量化參數(shù)影響最優(yōu)編碼單元（CU）模式的選擇，提出在CU模式判決過(guò)程中，使用最大編碼單元初始分割深度預(yù)測(cè)算法跳過(guò)部分大塊CU的模式判決；使用提前終止CU模式算法避免小塊CU的模式判決。實(shí)驗(yàn)結(jié)果表明，相比于原始的H.265/HEVC編碼算法，本文所提算法可平均降低51%的編碼復(fù)雜度，，而編碼碼率平均只上升了0.69%。 3.針對(duì)H.265/HEVC編碼器，提出一種考慮視頻內(nèi)容特性的幀層碼率分配算法。一般的，視頻內(nèi)容特性不同，其編碼輸出的比特?cái)?shù)就有所差異。為了保證目標(biāo)碼率與編碼碼率的一致性，在進(jìn)行幀層目標(biāo)碼率分配時(shí)，應(yīng)考慮幀內(nèi)容的復(fù)雜度。本文首先從理論推導(dǎo)的角度得出幀內(nèi)容特性與碼率之間的關(guān)系。然后提取出反映幀內(nèi)容特性的參數(shù)，建立一種更有效的幀層碼率分配算法。實(shí)驗(yàn)結(jié)果表明，本文所提算法可以使幀層目標(biāo)碼率與編碼碼率保持更好的一致性，且重構(gòu)視頻質(zhì)量平均提高了0.128dB。 4.針對(duì)H.265/HEVC的幀間殘差，提出了一種考慮變換系數(shù)依賴性的碼率模型。碼率模型的建立受信源特性和具體編碼算法的影響。本文首先分析了幀間塊內(nèi)變換系數(shù)的分布情況，提出使用基于TU層的混合拉普拉斯概率模型來(lái)描述信源特性。其次考慮到變換系數(shù)之間存在依賴性，且這種依賴性被用于CABAC中，因此提出使用互信息量來(lái)衡量CABAC編碼后不確定性的減小量，最終利用條件熵來(lái)預(yù)測(cè)幀間殘差系數(shù)的編碼碼率。實(shí)驗(yàn)結(jié)果表明，本文所提的碼率模型具有高的準(zhǔn)確性。此外本文所提模型可以擴(kuò)張到其他使用CABAC編碼的視頻編碼器中，用于碼率模型的設(shè)計(jì)。 5.針對(duì)客觀質(zhì)量，提出了一種考慮丟包內(nèi)容特性的無(wú)參考質(zhì)量測(cè)度模型。丟包是引起網(wǎng)絡(luò)語(yǔ)音質(zhì)量下降的主要因素，其影響程度不僅與丟失包的個(gè)數(shù)有關(guān)，而且與丟失包的內(nèi)容特性有關(guān)。首先利用話音激活檢測(cè)技術(shù)和未丟幀的電平來(lái)判斷丟失包的內(nèi)容特性，然后統(tǒng)計(jì)語(yǔ)音包的丟失率，進(jìn)而提出一種無(wú)參考的網(wǎng)絡(luò)語(yǔ)音質(zhì)量評(píng)價(jià)模型來(lái)預(yù)測(cè)網(wǎng)絡(luò)失真語(yǔ)音質(zhì)量。實(shí)驗(yàn)結(jié)果表明，相比于國(guó)際標(biāo)準(zhǔn)G.1070中的語(yǔ)音質(zhì)量評(píng)價(jià)模型，本評(píng)價(jià)模型與主觀質(zhì)量評(píng)價(jià)的相關(guān)性平均提高了8.4%。
[Abstract]:With the rapid development of multimedia services and the increasing demand of users for video quality , video coding technology has been improved and updated continuously . At present , H.264 / AVC has been widely infiltrated into various media products by virtue of its high coding performance . However , because of the better user experience , the ultra - high definition video business has gradually entered people ' s field of view , but its large amount of data makes storage and transmission face severe test . For this , JCTVC of video coding has developed the next generation video coding standard H.265 / HEVC to further improve the video compression efficiency .

This paper focuses on the H.264 / AVC , H.265 / HEVC mode decision module and H.265 / HEVC code rate control module based on rate distortion optimization .

1 . Aiming at the high complexity of mode decision in H.264 / AVC , a fast rate estimation algorithm is proposed . This paper first analyzes the basic principle of context adaptive binary algorithm coding ( CABAC ) , and the syntax element characteristics involved in the residual block . Based on this analysis , a valid residual error rate estimation algorithm is proposed to replace the actual CABAC coding in the mode decision . On the other hand , the proposed algorithm can accurately estimate the coding rate of the residual block .

2 . Aiming at the coding complexity problem of H.265 / HEVC , a new fast mode decision algorithm is proposed . Considering the texture characteristics of the video frame and the quantization parameter adopted in the coding , the selection of the optimal coding unit ( CU ) mode is proposed . In the process of the CU mode decision , the mode decision of the partial large CU is skipped using the initial segmentation depth prediction algorithm of the maximum coding unit ;
The results show that compared with the original H . 265 / HEVC coding algorithm , the proposed algorithm can reduce the coding complexity by 51 % , while the average code rate only increases by 0.69 % .

3 . Aiming at the H.265 / HEVC encoder , a frame layer code rate allocation algorithm considering the characteristics of video content is proposed . In order to ensure the consistency of the target code rate and the coding rate , the complexity of the frame contents should be taken into account in order to ensure the consistency between the target code rate and the code rate .

4 . Aiming at the inter - frame residual of H . 265 / HEVC , a code rate model considering the dependence of transform coefficients is proposed .

5 . Aiming at the objective quality , a non - reference quality measure model considering the characteristics of packet loss is proposed . The packet loss is the main factor which causes the decrease of the network voice quality . The influence degree is related not only to the number of lost packets , but also to the content characteristics of the lost packets . First , the loss rate of the lost packet is determined by using the voice activation detection technique and the level of the unlost frame . The experimental results show that the correlation between the evaluation model and the subjective quality evaluation is improved by 8.4 % compared with the speech quality evaluation model in the international standard G.1070 .

【學(xué)位授予單位】：西安電子科技大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TN919.81

【共引文獻(xiàn)】

相關(guān)博士學(xué)位論文 前1條

1 鄭莉華;H.264/AVC視頻編碼的碼率控制及并行處理研究[D];電子科技大學(xué);2013年

本文編號(hào)：1780703