基于多视点视频编码的差错控制算法

 多视点视频编码(Multiview Video Coding,MVC)利用运动估计和视差估计取得了较好的编码性能,但在易错的网络环境下传输MVC视频码流,将导致差错在视点内与视点间进行扩散.针对多视点视频的编码特性,提出了一种端到端的失真度估计模型,并将此模型与率失真优化相结合得到一种基于联合信源信道的编码模式选择算法.实验结果表明该方法能够在易错网络环境下有效的提高多视点视频的传输效率.     

基于转移概率的多视点视频快速模式选择算法

针对多视点视频编码(MVC)中部分大宏块模式(SKI P/DIRECT模式,帧间16×16模式)相对于其它模式的计算复杂 度低,并且在编码所确定的最优模式中占有相当高比重的特点,本文提出一种基于转移概率 的多视点视频 快速模式选择算法。首先根据多视点视频当前编码宏块对应时间和视点间宏块及周围宏块的 位置几何关系, 建立宏块模式参考模型;其次比较参考模型中模式的时间相似度和视点间相似度;最后计算 模式之间的转 移概率,确定提前结束大宏块模式选择过程的阈值。实验结果表明,本文所提出的快速算法 平均节约MVC时间80.93%,编码质量平均下降0.04dB,码率平均增加0.27%。     

多视点与深度视频编码技术研究综述

多视点与深度视频(MVD)可以有效表示自由视点视频,减少了需传输视点的个数,该表达形式正受到越来越多的关注,如何对MVD进行高效编码尤为重要.介绍了自由视点视频的发展现状及国内外研究概况,详细讨论了深度图像的高效编码技术及多视点与深度联合编码技术,并对多视点与深度视频编码技术进行了总结及展望.     

多视点视频编码技术的专利分析

多视点视频编码技术MVC是3D视频技术中的重要技术,而3D视频技术是电视产业的未来。本文针对MVC技术在国内专利库进行了全面检索,并从统计结果初步分析了产业发展趋势、公司战略部署、国内外专利质量和专利保护意识的对比,为业内人士提供了相关信息的普及,在此基础上,进一步对国内产研结合的可行性进行了分析,通过产研联合申请的成功案例介绍,为国内的公司和高校的共同研发提供借鉴。     

基于感知的多视点视频编码宏块模式选择快速算法

多视点视频编码(MVC)采取可变块模式选择技术和 多参考帧技术显著提高了编码的压缩效率,但同时带来了巨大的 编码计算复杂度。为了降低MVC的计算复杂度,提出基于感知的快速MVC宏块模式选择 算法。基于人眼视觉感知的特点,利用视觉恰可察觉失真(JND)的概念建立MVC宏块的最优模 式和JND的联系,并利用该联系确定早期结束最优宏块模式选择过程的阈值,根据当前编码 宏块的JND与阈值的 关系自适应地减少每个编码宏块的模式搜索次数,进而减少MVC的方向搜索和参考帧搜索的 次数,以降 低编码的复杂度,提高MVC速度。实验结果显示,对于不同运动特性、内容、纹理信息、相 机间距和图像 尺寸的测试序列,提出的快速算法在率失真性能几乎不变的情况下平均节约76.00% 编码时间。     

一种改进的多视点视频编码预测结构

多视点视频编码(Muti-view Video Coding,MVC)标准采用预测关系固定的编码结构,不能根据视频序列调整预测关系,导致无法获得更好的编码效率.本文针对这一缺陷提出一种确定预测结构的方法,首先对图像进行下采样获得粗粒度图像,然后利用粗粒度图像间的灰度方差获得灰度相近的视点,最后对所选取的灰度相近的视点运用全局视差确定I-视点.经实验验证,本文的方法可以提高编码效率并减少编码中的缓存容量.     

一种新的视点间预测结构

多视点视频编码除应具有较高的编码效率外,还应该包括后向兼容性、时间随机访问和视点可分级性等,这些都主要取决于所采用的预测结构。目前所提供的多视点视频编码(Joint Multi-view Video Coding, JMVC)采用固定的视点间预测结构,难以适应复杂情况的多视点视频编码。该文综合考虑编码效率和用户随机访问等因素,根据多视点视频相关性分析自适应调整视点间预测结构,以获得较好的编码综合性能。试验结果表明,与JMVC相比,该文的方法在提高编码效率的同时,有较好的随机访问性能。     

高效率的多视点视频编码预测结构*

预测结构是多视点视频编码(Multi-View Video Coding,MVC)研究的主要内容之一。MVC目前采用HHI(Heinrich-Hertz-Institute)提出的分层次B帧预测结构(HBP),比联播预测结构获得了更好的压缩效率。分析了多种预测结构,并针对平行摄像机采集的多视点视频序列,提出了一种新的预测结构AS_EIPP,该结构充分利用相邻视点间的相关性和多参考帧模式,进一步提高了压缩效率。在多视点视频软件测试平台JMVC8.3上进行验证,实验结果表明:新的预测结构在保证重建视频质量基本不变的前提下,压缩效率比HBP预测结构提高了1%～4%。     

多视视频编码标准MVC

近年,三维电视、自由视点电视等应用得到了相关工业界与产业界的极大关注与推动。国际标准化组织ITU-T与ISO,IEC联合制定了多视视频编码标准（MVC,Multi—view Video Coding standard）,为三维电视、自由视点电视等应用提供了高效的信源编码方案。MVC标准以H．264／AVC标准补篇（Amendment）的形式出现,它继承并发展了H．264／AVC标准的高效编码技术,并后向兼容H．264／AVC标准。这确保了MVC标准技术的先进性与应用实施的可行性。本文对MVC标准的目标应用、技术需求、技术情况、性能、应用前景等方面进行介绍和分析。     

沉浸式视频编码技术综述

随着虚拟现实、增强现实等沉浸式媒体技术的发展,沉浸式视频的表示、存储、传输和显示等各个环节都受到了科研及产业界的广泛关注。沉浸式视频更复杂的视频特性和庞大的数据量,对传统视频编码技术提出了挑战,新的编码技术应运而生。该文从视频自由度(DoF)出发,分别从3DoF和6DoF两个方面介绍沉浸式视频编码技术的最新成果。3DoF视频相关编码技术包括投影模型、运动估计模型和3DoF视频编码标准。6DoF视频相关编码技术包括视频表示形式、虚拟视点合成技术、6DoF视频编码技术及运动图像专家组沉浸式视频(MPEG, MIV)编码标准。最后,对沉浸式视频及其编码技术的发展进行总结和展望。     

Comparative Interactivity Analysis in Multiview Video Coding Schemes

In a multiview video system, interactivity is important for users and should be considered in the design of multiview video coding (MVC). In this paper, we present an interactivity evaluation model for MVC schemes by using both weighted random graph and Markov approaches. The main factors that affect both the interactivity and rate‐distortion (RD) performances of MVC schemes are analyzed and discussed in detail. By taking these factors into consideration, a new MVC scheme is proposed for high interactivity and RD gains. Experimental results show that the proposed scheme has a significant interactivity gain with little coding loss, compared to the state‐of‐the‐art benchmark. As an extension to RD performance analysis, the interactivity evaluation model can be used as a design tool of alternative schemes for a future interactive multiview video system.     

Adaptive Multiview Video Coding Scheme Based on Spatiotemporal Correlation Analyses

In this paper, we propose an adaptive multiview video coding scheme based on spatiotemporal correlation analyses using hierarchical B picture (AMVC‐HBP) for the integrative encoding performances, including high compression efficiency, low complexity, fast random access, and view scalability, by integrating multiple prediction structures. We also propose an in‐coding mode‐switching algorithm that enables AMVC‐HBP to adaptively select a better prediction structure in the encoding process without any additional complexity. Experimental results show that AMVC‐HBP outperforms the previous multiview video coding scheme based on H.264/MPEG‐4 AVC using the hierarchical B picture (MVC‐HBP) on low complexity for 21.5%, on fast random access for about 20%, and on view scalability for 11% to 15% on average. In addition, distinct coding gain can be achieved by AMVC‐HBP for dense and fast‐moving sequences compared with MVC‐HBP.     

Iterative search strategy with selective bi-directional prediction for low complexity multiview video coding

The multiview video coding (MVC) extension of H.264/AVC is the emerging standard for compression of impressive 3D and free-viewpoint video. The coding structure in MVC adopts motion and disparity estimation to exploit temporal and inter-view dependencies in MVC. It results in a considerable increase in encoding complexity. Most of the computational burden comes from uni-directional and bi-directional prediction. In this paper, an iterative search strategy is designed to speed up the uni-directional prediction in MVC. It can work with an adaptive search range adjustment through a confidence measure of a loop constraint to obtain both motion and disparity vectors jointly. Furthermore, a selective bi-directional prediction algorithm is proposed to enhance the coding performance by analyzing the statistical characteristics of bi-directional prediction in MVC. Experimental results demonstrate that, by using the proposed fast search, the temporal and inter-view redundancies of multiview video can be eliminated sufficiently with low complexity.     

Multiview coding and error correction coding for 3D video over noisy channels

We consider the joint source–channel coding problem of stereo video transmitted over AWGN and flat Rayleigh fading channels. Multiview coding (MVC) is used to encode the source, as well as a type of spatial scalable MVC. Our goal is to minimize the total number of bits, which is the sum of the number of source bits and the number of forward error correction bits, under the constraints that the quality of the left and right views must each be greater than predetermined PSNR thresholds at the receiver. We first consider symmetric coding, for which the quality thresholds are equal. Following binocular suppression theory, we also consider asymmetric coding, for which the quality thresholds are unequal. The optimization problem is solved using both equal error protection (EEP) and a proposed unequal error protection (UEP) scheme. An estimate of the expected end-to-end distortion of the two views is formulated for a packetized MVC bitstream over a noisy channel. The UEP algorithm uses these estimates for packet rate allocation. Results for various scenarios, including non-scalable/scalable MVC, symmetric/asymmetric coding, and UEP/EEP, are provided for both AWGN and flat Rayleigh fading channels. The UEP bit savings compared to EEP are given, and the performances of different scenarios are compared for a set of stereo video sequences.     

Overview of the MVC + D 3D video coding standard

3D video services are emerging in various application domains including cinema, TV broadcasting, Blu-ray discs, streaming and smartphones. A majority of the 3D video content in market is still based on stereo video, which is typically coded with the multiview video coding (MVC) extension of the Advanced Video Coding (H.264/AVC) standard or as frame-compatible stereoscopic video. However, the 3D video technologies face challenges as well as opportunities to support more demanding application scenarios, such as immersive 3D telepresence with numerous views and 3D perception adaptation for heterogeneous 3D devices and/or user preferences. The Multiview Video plus Depth (MVD) format enables depth-image-based rendering (DIBR) of additional viewpoints in the decoding side and hence helps in such advanced application scenarios. This paper reviews the MVC + D standard, which specifies an MVC-compatible MVD coding format.     

面向HBP编码格式的立体视频B帧整帧丢失分层错误隐藏算法

针对分层B帧(HBP)编码格式的立体视频B帧整帧丢失的问题,该文分析了双视点视频中存在的视点间运动矢量相关性,提出一种分层错误隐藏算法。该算法与当前主流的方法有两大不同:一是该算法采用分级隐藏,根据B帧的重要性等级不同采用不同的错误隐藏方法;二是该算法考虑了相邻视点序列之间的宏块运动矢量相关性。实验表明,该算法的性能优于当前常用的H.264多视点视频整帧丢失错误隐藏方法。     

Efficient early direct mode decision for multi-view video coding

Multi-view video coding (MVC) uses various prediction modes and exhaustive mode decision to achieve high coding efficiency. However, the introduced heavy computational complexity becomes the bottleneck of the practical application of MVC. For this, an efficient early Direct mode decision for MVC is proposed in this paper. Based on the observation that the Direct mode is highly possible to be the optimal mode, the proposed method first computes the rate distortion (RD) cost of the Direct mode and compares this RD cost value with an adaptive threshold for providing an early termination chance as follows. If this RD cost value is smaller than the adaptive threshold, the Direct mode will be selected as the optimal mode and the checking process of the remaining modes will be skipped; otherwise, all the modes will be checked to select the one with the minimum RD cost as the optimal mode. Note that the above-mentioned adaptive threshold is determined as the median prediction value of a set of thresholds, which are derived by using the spatial, temporal and inter-view correlations between the current macroblock (MB) and its neighboring MBs, respectively. Experimental results have demonstrated that the proposed method is able to significantly reduce the computational complexity of MVC with negligible loss of coding efficiency, compared with the exhaustive mode decision in MVC.     

Multiview depth coding based on combined color/depth segmentation

In this paper, a new coding method for multiview depth video is presented. Considering the smooth structure and sharp edges of depth maps, a segmentation based approach is proposed. This allows further preserving the depth contours thus introducing fewer artifacts in the depth perception of the video. To reduce the cost associated with partition coding, an approximation of the depth partition is built using the decoded color view segmentation. This approximation is refined by sending some complementary information about the relevant differences between color and depth partitions. For coding the depth content of each region, a decomposition into orthogonal basis is used in this paper although similar decompositions may be also employed. Experimental results show that the proposed segmentation based depth coding method outperforms H.264/AVC and H.264/MVC by more than 2 dB at similar bitrates.