视频编码的几种MPEG标准比较

对国际标准化组织ＩＳＯ制定的ＭＰＥＧ－１、ＭＰＥＧ－２、ＭＰＥＧ－４三种标准在视频编码方面作了综合比较,并着重介绍了ＭＰＥＧ－４视频编码中基于内容的功能。     

MPEG—4编码的现状和研究

随着计算机和通信技术的发展,多媒体编码进入了一个新的时代,即将公布的ＭＰＥＧ－４国际标准表明基于对象的编码,基于匠编码等第二代技术趋于成熟,文中首先从ＭＰＥＧ－４所支持的各种视频对象及其特点,场景的描述和不同应用的框架／级别等３个方面讨论了新的编码标准的主要内容和现状。新的标准用于实际应用还需要提供大量的标准之外的配套工具和研究。     

Win95下MPGE软解压的优化策略

本文简要描述了ＭＰＥＧ－１视频编码，解压模型，分析了ＭＰＥＧ－１比特流特点，讨论了基于ＰＣ的ＭＰＥＧ解压的主要问题，用Ｃ语言实现了一种从硬盘播放ＭＰＥＧ文件的软件压程序并重点讨论了ＭＰＥＧ－     

MPEG—4校验模型的研究与实现

本文主要是对ＭＰＥＧ－４校验模型（ＶＭ）关键技术进行研究,并实现了校验模型的编解码算法,主要包括形状、运动、纹理的压缩编码,在程序实现中形状编码采用基于内容的自述编码;运动编码在传统方法基础上做了改进;如半象素搜索、无限的运动失量、高级预测方式等;纹理编码主要还是用传统发ＤＣＴ、量化、变长编码码等,改进只是对帧内方式中ＤＣ、ＡＣ系数预测方法,现已实现了多个视频对象同时编码,解码时实现了ＭＰＥＧ－４     

快速形状自适应区域分割方法

为了实现基于内容的编码,在ＭＰＥＧ－４中引入了视频对象层的概念。ＳＡ－ＤＣＴ技术可以用于对ＶＯＰ中边缘块的编码,形状自适应区域分割方法可以提高ＳＡ－ＤＣＴ的编码效率,减少需要编码的块数,但相对较复杂。     

MPEG—4与基于对象的编码浅述

文章介绍了ＭＰＥＧ－４视频标准，详细地描述了其于对象编码的概念，并简明扼要地讨论了某些重要的实用算法与结构。     

MPEG—4标准及相关进展

ＭＰＥＧ－４标准面向众多而非特定的应用。本文介绍ＭＰＥＧ－４系统框架,接收端模型,系统层模型,视频对象平面向众多而非特定的基于模型编码和基于语义编码。     

新一代视音频标准MPEG—4与多媒体通信

多媒体通信的发展迫切需要一个有效的,功能强大的能支持所有产业的视音频编码标准,而现行的视音频标准ＭＰＥＧ－４。本文一开始对多媒体通信及其对视音频编码的要求进行了简要的介绍,然后对ＭＰＥＧ－４的主要特性及其在多媒体通信上的应用范围及前景作了详细的讨论。     

MPEG-2视频编码的色饱和度调整算法

给出了一种用于ＭＰＥＧ－２视频编码的色饱和度调整算法，该算法采用了神经网络分类器将ＭＰＥＧ－２当前帧每个像素的色差信号分成色饱和度很高，色饱和度高，色饱和度低和色饱和度很低等４个区，然后分别加权得到色差信号的总修正因子用以调整图象的色饱和度，仿真结果表明，视频解码图象的主客观质量都有明显改善，可以有效调整图象序列中欠饱和和过饱和的图象。     

可变比特率视频编码及其业务量特征分析

本文就可变比特率视频编码的概念及其在ＡＴＭ网络中传输的优势作了详细阐述对ＶＢＲ视频业务特征进行了分析,特别就目前广泛应用的ＭＰＥＧ视频业务做了大量的统计分析,为该业务建模奠定了基础。     

Coder selection for lossy compression of still images

A criterion for selecting a lossy coder for still images is proposed. The “optimum” coder using the proposed criterion is selected to minimize the maximum Chernoff information between the distribution for the original and any distribution from the optimal achievable region. The resulting coder has the property that the best achievable probability of error over the problems of hypothesis testing between these distributions, is greater than the best Bayesian error probability for any other choice of coder. The coder selection procedure may be applied without a knowledge of what distortion measure is more suitable for images or a knowledge of the properties of the human visual perception. Several examples of coder selection are included to illustrate the procedure.     

Bayesian AD coder: Mesh-aware valence coding for multiresolution meshes

The Alliez Desbrun (AD) coder has accomplished the best compression ratios for multiresolution 2-manifold meshes in the last decade. This paper presents a Bayesian AD coder which has better compression ratios in connectivity coding than the original coder, based on a mesh-aware valence coding scheme for multiresolution meshes. In contrast to the original AD coder, which directly encodes a valence for each decimated vertex, our coder indirectly encodes the valence according to its rank in a sorted list with respect to the mesh-aware scores of the possible valences. Experimental results show that the Bayesian AD coder shows an improvement of 8.5-36.2% in connectivity coding compared to the original AD coder despite of the fact that a simple coarse-to-fine step of the mesh-aware valence coding is plugged into the original algorithm.     

通用的高性能算术编码器

文中基于成熟的ＱＭ算术编码器,提出了对称二叉树的编码方式ＳＴＱＭ和最优二叉树的编码方式ＯＴＱＭ。ＳＴＱＭ与ＯＴＱＭ均是大符号集熵编码器。它们不仅保持了ＱＭ编码器的超过９６％的编码效率,也保持了它高速运算的特性。基中ＯＴＱＭ可以动态的调整码树结构,使得编码速度达到理论最优值。ＳＴＱＭ由于可并行性和逻辑线路设计简单等特点,使之适合于做动态旬图像的基于专用硬件设计的熵编码模块。     

Gaussian Mixture Kalman Predictive Coding of Line Spectral Frequencies

Gaussian mixture model (GMM)-based predictive coding of line spectral frequencies (LSFs) has gained wide acceptance. In such coders, each mixture of a GMM can be interpreted as defining a linear predictive transform coder. In this paper, we use Kalman filtering principles to model each of these linear predictive transform coders to present GMM Kalman predictive coding. In particular, we show how suitable modeling of quantization noise leads to an adaptive a posteriori GMM that defines a signal-adaptive predictive coder that provides improved coding of LSFs in comparison with the baseline recursive GMM predictive coder. Moreover, we show how running the GMM Kalman predictive coders to convergence can be used to design a stationary GMM Kalman predictive coding system which again provides improved coding of LSFs but now with only a modest increase in run-time complexity over the baseline. In packet loss conditions, this stationary GMM Kalman predictive coder provides much better performance than the recursive GMM predictive coder, and in fact has comparable mean performance to a memoryless GMM coder. Finally, we illustrate how one can utilize Kalman filtering principles to design a postfilter which enhances decoded vectors from a recursive GMM predictive coder without any modifications to the encoding process.     

G.729语音编码器在DSP上的实时实现

为满足音视频的同时需求,提出了基于TMS320C64X系列DSP的G.729语音编码器软、硬件设计方案,并着重阐述了在实时实现过程中进行优化的关键技术。经测试表明,优化后的单路语音编码占用了5%左右的CPU资源,比优化前降低了80%,保留了更多的资源用于视频编码,为在同一块DSP芯片上实现音频、视频编码提供可能。     

A Motion Compensated Lifting Wavelet Codec for 3D Video Coding

A motion compensated lifting (MCLIFT) framework for the 3D wavelet video coding is proposed in this paper. By using bi-directional motion compensation in each lifting step of the temporal direction, the video frames are effectively de-correlated. With the proper entropy coding and bit-stream packaging schemes, the MCLIFT wavelet video coder is scalable at frame rate and quality level. Experimental results show that the MCLIFT video coder outperforms the 3D wavelet video coder without motion by an average of 0.9-1.3dB, and outperforms MPEG-4 coder by an average of 0.2-0.6dB.     

编码器在水利工程弧形闸门中的应用

编码器的安装联接方式主要是根据闸门的不同形式和现场环境来决定的。一般来说,弧形闸主要有直联结和轴联结两种方式。采用不同的联结方式,开度测量方法也不同,对编码器的精度要求也有非常大的区别。     

Perceptual coding of narrow-band audio signals at low rates

This paper describes a coding paradigm using coding tools based on the characteristics of the human hearing system so as to accommodate a wide range of narrow-band audio inputs without annoying artifacts at low rates (down to 8 kb/s). The narrow-band perceptual audio coder (NPAC) employs a variety of algorithms to account for the perceptually irrelevant parts of the input signal in addition to statistical redundancies. The new algorithms used in the NPAC coder include a perceptual error measure in training the codebooks and selecting the best codewords which takes into account the audible parts of the quantization noise, a perception-based bit-allocation algorithm and a new predictive scheme to vector quantize the scale factors. The NPAC coder delivers acceptable quality without annoying artifacts for most narrow-band audio signals at around 1 bit/sample. Informal subjective tests have shown that the NPAC coder outperforms a commercial low-rate music coder operating at 8 kb/s.     

基于G.729的网络丢包自适应语音编码器

文章分析了错误隐藏技术在不同的网络丢包情况下的性能以及不同参数的敏感程度,提出了一种非对称网络丢包错误保护技术,并与G．729语音编码器相结合,提出了一种固定码率12．0kbps的网络自适应语音编码器。实验表明其具有良好的效果。     

面向对象分配带宽的极低比特率视频编码器

在低比特率环境下,如何提高图象编码质量是许多人感兴趣的课题,针对此问题,提出了一种面向对象分配带宽（OOBA）的视频编码器,用以提高低比特率环境下编码图象的主观质量,在充分考虑人的主观视觉特性的基础上,该编码器把图象序列分成不同的视频对象,而每个对象以宏块为单位构成,并且对每个对象单独分配大小不同的带宽,以把更多的比特分配人主观感兴趣的对象,来达到在低比特率环境下提高编码图象主观视觉质量的目的。虽然每个对象独立编码,但在比特流的组织上却能与H．263兼容。为了合理地在多个对象间分配带宽,还给出了基于速率－失真（R－D）模型、基于序列分析和比值加权法等3种带宽分配方法。实验结果表明,该编码器与传统的基于帧的编码器相比,在极低的速率下,峰值信噪比虽略有降低,但图象的视觉质量却得到较大的提高。从而表明了该编码器的有效性,也说明在低比特率环境下,仅以客观准则作为评价编码器好坏的标准是不够的。