一种极低码率视频压缩编码算法的VLSI结构

本文提出了一种基于分类矢量量化的极低码率视频编码算法及其ＶＬＳＩ结构,它结合了四叉树分割,分类矢量量化算法,变块大小运动估计等多种算法,在获得较高压缩率同时,又克服了低码率图像编码算法中常见的边缘细节模糊的缺陷,同时,本算法在保留了矢量量化解码顺简单的优点的同时,并给出了一种易于ＶＬＳＩ实现的编码器结构,其中运动估计电路可和矢量量化器共用处理器阵列,从而减少了编码器的电路规模。’     

多媒体通信的视频压缩技术

多媒体通信是一项综合的技术,涉及多媒体、计算机及通信等领域,它集计算机的交互性、网络的分布性和多媒体信息的综合性于一体,突破了计算机、通信、电视和出版等传统产业间的界线,使这些对人类社会产生重大影响但相对独立发展的技术融为一体。它向人类提供了全新的信息服务,如:多媒体电子邮件、实时视频会议、计算机支持的协同工作以及远距离学习和远距离医疗等。它的应用将对人类的生活和生产方式产生深远的影响。并进一步加速信息高速公路的建设。     

"视频压缩编码及多媒体通信"的教改探讨

"视频压缩编码及多媒体通信"是通信工程、电子工程等重要的专业课程.本文针对该课程在教学内容选取、实验环节等方面存在的问题,提出通过匿名问卷调查,更新教学内容,增加课堂演示实验和课程实验环节、SIT计划和科研成果进教材、毕业设计、课堂和实验项目等手段进行教学改革尝试,在学生的学习兴趣和创新能力培养等方面取得了较好的效果.     

极低码率电视电话中的视频压缩技术

本文综述用于新一代可视通信系统中的极低码率视频编码技术及其发展动态.     

视频压缩编码的国际标准

为了使视频通信能更有效地利用信道带宽和存储空间，必须对视频数据进行压缩编码，在介绍了视频压缩编码的基本方法以后，着重叙述应用范围从静止图像到ＨＤＴＶ的国际视频编码标准或方案，其中包括ＪＢＩＧ，ＪＰＥＧ，Ｈ．２６１，ＭＰＥＧ和ＨＤＴＶ等，最后，对视频压缩领域的应用现状和前景作了一些分析。     

MPEG视频编码中的码率控制原理及算法

对视频码流的特点、码率控制的目的、码率控制的关键因素、CBR虚拟缓冲器限制等问题进行了详细分析，同时介绍了MPEG-4校验模型所推荐的码率控制算法。     

可伸缩性视频编码的码率分配算法

本文研究了渐进的精细的可伸缩性(Progressive Fine Granular Scalable,PFGS)视频编码的增强层码流的码率分配问题,它是由PFGS各帧的增强层码流长度不同引起的.我们首先建立了PFGS增强层的多帧联合的率失真(rate-distortion,R-D)函数,并通过MPEG-4标准测试序列检验了它的正确性.然后利用联合率失真函数给出了局部最优的码率分配算法,并进行了简化使得它的复杂性极低,非常适合流化视频(streaming video)服务器使用.实验结果显示本文提出的算法不仅使得各帧图像的解码质量比较平衡,而且将PFGS的编码效率提高了将近0.5dB.     

基于H.264编码算法的高速CCD视频压缩系统设计

为了满足航空大面阵CCD相机视频数据高速、实时传输和存储的要求,本文设计了一种基于H.264视频编码算法的压缩系统。整个压缩系统分为CCD前端、视频压缩、视频显示、视频压缩码流存储以及压缩分析单元,视频压缩单元采用高性能视频专用DSP处理器TMS320DM642,软件平台采用在CCS3.1上使用C语言实现H.264压缩算法。为了使压缩算法高效快速的运行,本文使用了DSP/BIOS资源来管理软硬件工作。 为了高速交互数据,采用了EDMA高速搬运数据策略,进而保证了数据实时传输的需要。实验结果表明,本文提出的压缩系统可以稳定正常的工作,具有良好压缩性能,在压缩比40:1~10:1范围内,平均信噪比高于35dB,满足了航空CCD相机应用的需求。     

低码率视频压缩技术的块效应消除方法

低友率视频压缩技术是多媒体通信的关键技术。基于块编码的低码率视频压缩技术中,块效应现象成为比较突出的问题。本文讨论了低码率视频压缩中消除块效应的方法,提出了基于约束复原原理的一种具体块效应消除方法,并根据计算机软件实现的分析,得出了结论采用约束复原的块应消除方法可以同时提高客观ＰＳＮＲ值和改善块应现象。     

基于ROI区域的极低比特率编码算法

在极低比特率视频编码算法中,对感兴趣区域(ROI)优先进行编码能够获得更好的重建图像质量.在本文中,我们讨论了一种基于彩色直方图的人脸跟踪技术,它能够在头肩像图像序列中简单有效的准确定位ROI区域(人脸区域),并且,本文还提出了一种被称为小波块集合划分(SPWB)的小波编码算法用来对视频序列进行帧内编码,编码试验的结果表明,在同样的压缩比下,SPWB编码器能够获得比H.26L帧内编码器更好的重建图像质量.     

ITU standardisation of very low bitrate video coding algorithms

The ITU near term standard for very low bitrate video coding, H.263 (ITU-T SG 15/1 Rapporteurs Group for Very Low Bitrate Visual Telephony, 1995), is described. Both QCIF and a sub-QCIF format (128 × 96) are mandatory picture formats for the decoder; the CIF picture format is optional. The H.263 algorithm consists of a mandatory core algorithm and four negotiable options. With H.263 a significantly better picture quality than with H.261 can be achieved, depending on the content of the video scene and the coding parameters. Also, the cost of the H.263 video codec can be kept low if only the minimum required is implemented. The negotiable options of H.263 increase the complexity of the video codec, but also significantly improve the picture quality. H.263 is part of a set of recommendations for a very low bitrate audio visual terminal that was frozen in January 1995 and is based on existing technology. A long term activity is planned by ITU for the development of a new video coding algorithm (H.263/L) with a considerable better picture quality than H.263. This standard will be developed in joint co-operation with MPEG4.     

Morphological shape representation for very low bit-rate video coding

Region-based coding schemes are among the most promising compression techniques for very low bit-rate applications. They consist of image segmentation, contour and texture coding. This paper deals with the use of the geodesic skeleton as a morphological tool for contour coding of segmented image sequences. In the geodesic case, already coded and known regions are taken into account for the coding of contours of unknown regions. A new technique is presented for the entropy coding of the coordinates of the skeleton points exploiting their special spatial distribution. Furthermore, a fast algorithm for the reconstruction of the skeleton points is given based on hierarchical queues. In the case of numerous isolated contour arcs (for example error coding in a motion prediction loop), the geodesic skeleton proofs higher efficiency than traditional methods. Results at very low bit-rates are presented and compared to standard methods confirming the validity of the chosen approach.     

区域追踪匹配甚低码率视频编码算法的研究

本文提出一种基于Gabor变换区域追踪匹配RMP（region matching pursuit)的甚低码率视频编码算法,用于克服块编码带来的块效应及其明显失真;根据图像区域特征重要性优先级选择编码保证编码质量（PSNR）;通过算法自学习实现Gabor追踪匹配集优化提高编码效率。实验测试结果表明,在甚低码率（24kbit/s和10kbit/s）下区域追踪匹配算法与H．263编码算法相比,能够有效保证视频编码质量（PSNR）,降低块效应,有较高的编码效率。同时算法具有码率及PSNR扩展功能。     

一种基于多视点视频的低复杂度自适应环路滤波算法

自适应环路滤波(ALF)是面向高清的多视点视频编码(MVC)中的一项新的滤波技术,虽然能提高视频压缩的主观质量和客观质量,但是其复杂度过高阻碍了其实时应用。本文提出了一种低复杂度的ALF算法,充分利用了视点间相关性和层间相关性以减少亮度和色度分量的分割次数,并且能自适应跳过大部分帧的块控制(DBC)处理过程。实验结果表明,所提出的算法能在保证视频主观质量和客观质量基本不变的情况下减少61%左右的ALF处理时间。因此,所提出的方法在编码效率和复杂度上做到了很好的折中处理,并且能很好地改善ALF的性能。     

甚低速视频编码中PB帧技术的研究

本文首先对甚低速视频编码H.263的PB帧技术和H.263+所采用IPB帧技术进行性能分析,在此基础上,提出一种简单有效的B帧选取方法(称之为B帧熵最大选取法),其基本思路是根据信息论熵值理论定义B帧的熵,并根据熵值来选择信息量最大、对暴露区补偿最有意义的B帧,实验结果表明该方法在保留了H.263+的IPB帧的优点的同时,可获得更优的补偿效果。     

A layered coding system for very low bit rate video coding

Known coding techniques for transmitting moving images at very low bit rates are explained by the source models on which these coding techniques are based. It is shown that with motion-compensated hybrid coding, object-based analysis-synthesis coding, knowledge-based coding and semantic coding, there is a consistent development of source models. In consequence these coding techniques can be combined in a layered coding system. From experimental results obtained for object-based analysis-synthesis, coding estimates for the coding efficiency of such a layered coding system are derived using head and shoulder video telephone test sequences. It is shown that an additional compression factor of about 3 can be expected with such a complex layered coding system, when compared to block-based hybrid coding.     

BLOCK ADAPTIVE RECURSIVE ALGORITHM FOR VIDEO CONFERENCE CODING

This paper presents a new motion estimation algorithm for video conference signal coding. This type of algorithm is called block adaptive recursive algorithm (BARA). Simulation results show that this new algorithm has better performance than conventional ones.     

Improved side information generation algorithm for Wyner-Ziv video coding简

Side information has a significant influence on the rate-distortion（RD） performance of distributed video coding（DVC）. In the conventional motion compensated frame interpolation scheme, all blocks adopt the same side-information generation method regardless of the motion intensity inequality at different regions. In this paper, an improved method is proposed. The image blocks are classified into two modes, fast motion and slow motion, by simply computing the discrete cosine transformation（DCT） coefficients at the encoder. On the decoder, it chooses the direct interpolation and refined motion compensated interpolation correspondingly to generate side information. Experimental results show that the proposed method, without increasing the encoder complexity, can increase the average peak signal-to-noise ratio（PSNR） by up to 1~ 2 dB compared with the existing algorithm. Meanwhile, the proposed algorithm significantly improves the subjective quality of the side information.     

Motion vector replensihment for low bit-rate video coding

A low bit-rate video codec based on motion vector replenishment is described. Motion vectors are used to update pictures at full frame rate. In addition, part of each frame is conditionally updated with a strip of interframe video data. The video data fill the remaining channel capacity not used for motion vectors. Thus under most conditions, each frame is fully updated by motion vectors and partially with interframe video data. This method has a comparable compression efficiency with that of the frame dropping method, but does not introduce any picture ‘jerkiness’. Finally the application of the proposed method to packet video networks is examined.     

一种适用于AVS-M的自适应快速运动估计算法

为了减小移动视频编码标准(AVS-M)中运动估计模块的复杂度,提出了一种快速、有效的块匹配运动估计算法.该算法充分利用了视频图像中运动矢量场的中心偏置特性和时空相关性,根据运动类型自适应的选择搜索起点和搜索策略,结合改进的搜索模板和高效搜索中止准则,有效地降低了运动估计的运算量.实验结果表明,该算法在保证搜索精度的同时,大大减少了搜索点数.