MPEG—4视频验证模型

ＭＰＥＧ－４是一个正在制定的编码标准,除了具有ＭＰＥＧ－１和ＭＰＥＧ－２标准的基于“帧”的功能以外,ＭＰＥＧ－４视频编码算法还支持多媒体环境中对视频景物内的“物体”进行存取与操纵。概述了ＭＰＥＧ－４视频编码标准将支持的新功能,并描述了第４版ＭＰＥＧ－４视频验证模型的结构。     

MPEG-4视频验证模型中基于内容的编解码算法

ＭＰＥＧ－４是一个正在制定的编码标准,除了具有 ＭＰＥＧ－１和 ＭＰＥＧ－２标准的基于“帧”的功能以外,ＭＰＥＧ－４视频编码算法还支持多媒体环境中对视频景物内的“物体”进行存取与操纵。文中描述了第四版ＭＰＥＧ－４视频验证模型的结构及其提供的主要编码工具和算法。     

MPEG—4视频验证模型中基于内容的编码码算法

ＭＰＥＧ－４是一个正在制定的编码标准,除了具有ＭＰＥＧ－１和ＭＰＥＧ－２标准的基于“帧”的功能以外,ＭＰＥＧ－４视频编码算法还支持多媒体环境中对视频景物内的“物体”进行存取与操纵。文中描述了第四版ＭＰＥＧ－４视频验证模型的结构及其提供的主要编码工具和算法。     

MPEG-4视频编码算法结构分析

ＭＰＥＧ－４与ＭＰＥＧ－１和ＭＰＥＧ－２视频处理方式的最大区别是在ＭＰＥＧ－４中引入了视频对象ＶＯ的概念,对ＭＰＥＧ－４基于内容的视频编码方式进行了描述,并重点分析了ＭＰＥＧ－４视频编码算法的结构特点。     

多媒体通信中MPEG—4视频编码算法的结构

为了共同发展多媒体视频编码技术，活动图象专家组建立了ＭＰＥＧ－４视频检验模型。它为ＭＰＥＧ－４标准的发展描述了核心视频编码算法平台。ＭＰＥＧ－４的最后标准可能采用这些算法和工具，下文不ＭＰＥＧ在多媒体通信中的发展作一简要介绍，并阐述ＭＰＥＧ－４视频检验模型中视频编码算法的结构。     

MPEG—4中的Profiles及适用场合

ＭＰＥＧ－４提供了极其丰富的工具集用于对音／视频对象编码。在实现ＭＰＥＧ－４标准时,可以根据应用领域的不同有选择地使用合适的视频、音频、图形和场景描述工具子集,这样可提高编解码器的工作效率。那些面向不同应用的工具子集就称为Ｐｒｏｆｉｌｅｓ（档次）,它们限定了一个解码器必须实现的工具集。描述了ＭＰＥＧ－４标准中的Ｐｒｏｆｉｌｅｓ及适用场合。     

业界动态

ＭＰＥＧ－４版本２确定１９９９年１２月举行的第５０届ＭＰＥＧ会议上,ＭＰＥＧ－４版本２被作为ＦＤＩＳ（ＦｉｎａｌＤｒａｆｔＩｎｔｅｒｎａｔｉｏｎａｌＳｔａｎｄａｒｄ）标准正式得到承认。版本２在１９９９年９月认可的国际标准（ＩＳ：ＩｎｔｅｒｎａｔｉｏｎａｌＳｔａｎｄａｒｄ）版本１的基础上,增加了新型编码工具及其组合的标准协议;在图像处理方面增加了３维网眼编码、轮廓动画、超低编码率编码等技术;在音响处理方面则追加了可对应高错码率以及高延迟的工具。另外,ＭＰＥＧ－４版本２还追加了使用Ｊ。ａ的ＭＰＥＧ－…     

MPEG—4标准剖析

分析了ＭＰＥＧ－４的７个功能、ＭＰＥＧ－４视频编码规划、音频编码规划及ＭＰＥＧ－４应用举例等。     

MPEG-4一种适用于交互式业务的多媒体压缩标准

已制定了ＭＰＥＧ－１与ＭＰＥＧ－２的音视频压缩标准的活动图像专家组,目前正推出针对交互式多媒体应用的ＭＰＥＧ－４标准,作为一种高效的压缩标准,ＭＰＥＧ－４将提供基于内容的功能,即,独立地访问并操纵图像中的对象的可能性。并且,ＭＰＥＧ－４将有效的视频存储以用于在有限的音视频通道内以５ｋｂｉｔ／ｓ－４Ｍｂｉｔ／ｓ的码率传输信号,还概述了ＭＰＥＧ－４的技术发展现状,并侧重于讨论在交互式应用中占重要地们的     

音频—视频压缩技术

数字音频和视频的多种形式的信息通过各种媒体自由地传给我们，这是由于ＭＰＥＧ技术标准对音频－视频信息的压缩和在对目前的模拟媒体的数字化处理技术方面的改进产生的效果。文中给出了基本原理和ＭＰＥＧ委员会在ＭＰＥＧ－１和ＭＰＥＧ－２的标准发展中的活动，并且还包括为发展提供新功能的音频－视频信息编码模型的新标准的情况。     

Near-Stoichiometric Ti : LiNbO$_{3}$ Strip Waveguides Fabricated by Standard Ti Diffusion and Post-VTE

We report near-stoichiometric (NS) Ti : LiNbO$_{3}$ waveguides fabricated by indiffusion of 4-, 5-, 6-, 7- $mu{hbox {m}}$-wide 120-nm-thick Ti-strips at 1060 $^{circ}hbox{C}$ for 10 h into a congruent $hbox{LiNbO}_{3}$ (i.e., standard Ti diffusion procedure) and post-vapour-transport-equilibration (VTE) treatment at 1100 $^{circ}hbox{C}$ for 5 h. These waveguides are NS and single-mode at 1.5 $mu{hbox {m}}$, and have a loss of 1.0/0.8 dB/cm for the TM/TE mode. In the width/depth direction of the waveguide, the mode field follows a Gauss/Hermite–Gauss profile, and the Ti profile follows a sum of two error functions/a Gauss function. The post-VTE resulted in increase of diffusion width/depth by 2.0/1.0 $mu{hbox {m}}$. A two-dimensional refractive index profile in the guiding layer is suggested.      

基于“bag of words”的视频匹配方法

提出了一种利用“bag of words”模型对视频内容进行建模和匹配的方法。通过量化视频帧的局部特征构建视觉关键词（visual words）辞典，将视频的子镜头表示成若干视觉关键词的集合。在此基础上构建基于子镜头的视觉关键词词组的倒排索引，用于视频片段的匹配和检索。这种方法保留了局部特征的显著性及其相对位置关系，而且有效地压缩了视频的表达，加速的视频的匹配和检索过程。实验结果表明，和已有方法相比，基于“bag of words”的视频匹配方法在大视频样本库上获得了更高的检索精度和检索速度。     

Application Specific Processor Design for H.264 Decoder with a Configurable Embedded Processor

An application specific processor for an H.264 decoder with a configurable embedded processor is designed in this research. The motion compensation, inverse integer transform, inverse quantization, and entropy decoding algorithm of H.264 decoder software are optimized. We improved the performance of the processor with instruction‐level hardware optimization, which is tailored to configurable embedded processor architecture. The optimized instructions for video processing can be used in other video compression standards such as MPEG 1, 2, and 4. A significant performance improvement is achieved with high flexibility. Experimental results show that we could achieve 300% performance for the H.264 baseline profile level 2 decoder.     

A Modified Access Policy for ETHERNETTMVersion 1.0 Data Link Layer

A modification to the access policy for ETHERNET^TMVersion 1.0 is proposed. By placing additional restrictions (compared with ETHERNET) on each station that is attempting to transmit, this access policy makes it more likely a successful message transmission will occur, and in less time, than the published Version 1.0. Theoretical analysis substantiates these claims.     

Rate control based on linear regression for H.264/MPEG-4 AVC

An efficient rate control algorithm is required to transmit coded video sequences without abrupt changes in quality due to the limited channel bandwidth. Thus, in this paper, an efficient rate control method is proposed for the H.264/MPEG (Moving Picture Experts Group)-4 Advanced Video Coding (AVC) baseline profile that meets the above constraint by using a ρ-domain source model. Firstly, a simple target bits determination method that considers the ideal buffer level is proposed, and secondly, a method of adequately determining the Quantization Parameter (QP) is presented using two kinds of linear regression. The experimental results show that the proposed rate control algorithm using the above two methods performs better than other rate control algorithms for H.264/MPEG-4 AVC in terms of the rate estimation error and the standard deviation of the Peak Signal-to- Noise Ratio (PSNR), which provides a measure of the constancy of the video quality throughout the whole video sequence.     

The rate variability-distortion (VD) curve of encoded video and its impact on statistical multiplexing

Encoded video is expected to contribute a significant portion of the load on future communication systems and networks, which often employ statistical multiplexing. In such systems, the number of video streams that can be supported depends both on the mean bit rate as well as bit rate variability of the video streams. At the same time, the utility (revenue) earned from video streaming depends both on the number of supported video streams as well as their quality level. In this paper we examine the interplay between video quality, traffic variability, and utility for open-loop encoded video. We introduce the rate variability-distortion (VD) curve which relates the bit rate variability to the quality level of an encoded video. We find that the VD curve generally exhibits a characteristic "hump" behavior of first increasing, peaking, and subsequently decreasing variability for increasing quality. We examine the impact of video content characteristics, encoding parameters, and traffic smoothing on the VD behavior. We describe a methodology for assessing (i) the set of the video streams that can be supported with a statistical quality of service requirement, and (ii) the utility earned from video streaming over a link. This methodology is based on the rate-distortion and rate variability-distortion characteristics of the videos. We find that the statistical multiplexing gain and the utility as a function of the video quality level typically exhibit a "hump" similar to the VD curve.     

一种MPEG2视频解码器的系统设计

对于设计像 MPEG2视频解码器的复杂系统 ,关键的难点是其系统结构的设计。文中设计了一种适合 VL SI实现的 MPEG2解码器的系统结构。它支持 MPEG2 (MP@ML)码流 ,并且兼容 MPEG1码流。为了设计和优化这个结构 ,采用硬件描述语言 VHDL 设计了系统级的 MPEG2视频解码器。此解码器在 Viewlogic系统中进行了模拟 ,并且对一些码流进行了测试验证。     

运营商以第二屏服务和CDN 增强IPTV业务吸引力

当前,面对未来多屏融合的趋势,全球很多电信运营商都在积极推动"第二屏服务"或者通过改善自己的CDN网络,应对有线电视和互联网电视的挑战。所谓"第二屏服务",可以简单理解为电信运营商将手机或平板电脑演变为电视机的第二屏,增强IPTV等电视业务的吸引力,包括利用手机客户端应用,提供节目搜索、节目竞