MPEG-4标准中的视频编码

MPEG－4是一个全新的多媒体标准,采用了基于对象和模型的编码方法,本文简要总结了MPEG－4视频编码的各种特点,并对其中的纹理编码、形状编码、静止纹理编码、脸部对象编码、网格对象编码、Sprite对象编码以及可分级编码作了简要的介绍。     

流媒体中的MPEG-4编码技术

介绍了流媒体应用的视频编码技术的发展和标准，通过对MPEG-4编码模型的描述，论述了视频对象、视频对象面、视频对象层的概念，以及精细可扩展性、渐进精细可扩展性、精细的空域可扩展性视频编码算法。     

高效率编码的动向

以音响信号为中心，对高效率编码进行概略性考察。首先讲解了高效率编码的理论基础，然后介绍了种种高效率编码方式，特别是这几年提出的一些以高、中音质音响信号为对象，利用了听觉特性的新的高效率编码方式。     

MPEG-4标准的介绍及其应用

MPEG-4是一个全新的多媒体标准，采用了基于对象和模型的编码方法。本文就它的主要功能和特点以及编码原理和应用作详细介绍。     

MPEG—4中的视频编码技术

MPEG-4图像压缩编码方法是基于对象和内容的现代编码方法，顺应了现代图像压缩编码的潮流，广泛用在多媒体通信及第三代移动通信系统中。本主要介绍了MPEG-4视频对象的压缩编码方法及其差错控制方法。     

MPEG-4中视频对象平面的形状编码

首先介绍了MPEG-4中视频对象平面(VOP)形状编码的流程，然后分别介绍了VOP形状编码的各个步骤，最后提出了一种基于H．263的MPEG-4视频编码器简单框架(Simple子Pmfile)的实现方法。     

基于对象视频编码模型及其功能简介

在引入ＭＰＥＧ－４规视标准的基础上,对基于对视频编码模型及功能进行了描述,介绍了基于对象编码的概念及某些算法结构。     

H．264在视频会议系统中的应用

文章在研究视频编码算法的基础上，介绍了视频编码发展的历程，比较了当今主流视频编码的特点，分析各自的优缺点。由于H．264具有编码效率高以及视频质量优越的特性，所以文章将这一当前最热门的视频编码标准作为重点研究分析的对象。     

无线网络中的物理层网络编码技术

文章介绍了无线网络中的物理层网络编码技术。首先介绍了一种在物理层实现的结合网络编码和纠错编码的方法。然后介绍了一种模拟网络编码方法,该方法可以充分利用无线介质的广播特性,挖掘无线广播信道和无线多址接入信道的容量,从而提高数据吞吐量。最后介绍了物理层网络编码的研究热点。     

一种基于DCT域的分布式视频编码

在简单介绍空域Wyner-Ziv分布式视频编码的基础上,给出了一种编码复杂度较低的基于交换域分布式视频编码方法.仿真结果表明此算法的编码性能优于空域Wyner-Ziv编码算法.     

面向对象视频编码模型

目前 ,面向对象的视频编码已成为研究热点。MPEG - 4,MPEG - 7等标准的提出促进了面向对象编码技术的发展 ,同时也使得基于内容的视频检索的应用成为可能。对面向对象的视频编码技术进行深入探讨。在面向对象的视频编码标准中 ,视频序列中的图像被表示为视频对象的集合 ,这样不仅可以提高编码效率 ,同时可以支持面向对象编码和实现基于内容的应用 ,还能帮助提取语义视频对象     

Object-based coding of stereoscopic and 3D image sequences

The author begins by discussing what object based coding is and goes on to consider the structure of object based stereoscopic coders. Different techniques for object-based stereoscopic image sequence coding are reviewed. These techniques basically differ in the way they define models and estimate model parameters. We review the various models used for representing motion and structure. Then we review segmentation techniques, and discuss coding of object parameters and image synthesis     

L2范数正则化鲁棒编码视觉跟踪

针对基于稀疏表示的视觉跟踪计算效率低和易于产生模型漂移的不足,该文提出一种基于L2范数正则化鲁棒编码的视觉跟踪方法。该方法利用L2范数正则化鲁棒编码求解候选目标的编码系数,以粒子滤波为框架,利用候选目标的加权重建误差建立似然模型跟踪目标。为了适应目标的变化并克服模型漂移问题,利用L2范数正则化鲁棒编码估计当前目标的加权矩阵用于遮挡检测,根据遮挡检测结果实现模型更新。对提出的跟踪方法进行实验的结果表明:与现有跟踪方法相比,该方法具有较优的跟踪性能。     

视频编码参数对目标识别性能影响的研究

国内外研究人员对图像目标分类识别和视频编码传输问题都分别进行了大量研究,但是对于视频编码参数对目标识别性能影响的定量关系,还没有公开的文献报导。针对这一问题,该文选择典型的目标识别算法可变部件模型(DPM)和最常用的视频编码方法H.264/AVC作用测试对象,通过设计的编码和检测实验,研究了码率和分辨率参数对视频目标识别性能的影响,并拟合了识别性能随码率和分辨率变化的函数关系。通过选取编码器合适的码率和分辨率工作参数,可以获得信道带宽与视频目标识别性能的折中,为设计不同视频应用的编码优化目标函数提供了依据。     

基于内容的视频编码技术

介绍了基于内容的交互性及视频对象面（ＶＯＰ）的新概念,给出了一种基于内容的视频编码系统框架,并展望了基于内容的视频编码的应用前景。     

Allowing content-based functionalities in segmentation-based coding schemes

This paper deals with the use of the segmentation tools and principles presented in [10] and [13] for allowing content-based functionalities. In this framework, means for supervised selection of objects in the scene are proposed. In addition, a technique for object tracking in the context of segmentation-based video coding is presented. The technique is independent of the type of segmentation approach used in the coding scheme. The algorithm relies on a double partition of the image that yields spatially homogeneous regions. This double partition permits to obtain the position and shape of the previous object in the current image while computing the projected partition. In order to demonstrate the potentialities of this algorithm, it is applied in a specific coding scheme so that content-based functionalities, such as selective coding, are allowed.     

Object-oriented analysis-synthesis coding based on moving two-dimensional objects

An object-oriented analysis-synthesis coder is presented which encodes arbitrarily shaped objects instead of rectangular blocks. The objects are described by three parameter sets defining their motion, shape and colour. Throughout this contribution, the colour parameters denote the luminance and chrominance values of the object surface. The parameter sets of each object are obtained by image analysis based on source models of moving 2D-objects and coded by an object-dependent parameter coding. Using the coded parameter sets an image can be reconstructed by model-based image synthesis. In order to cut down the generated bit-rate of the parameter coding, the colour updating of an object is suppressed if the modelling of the object by the source model is sufficiently exact, i.e., if only a relatively small colour update information would be needed for an errorless image synthesis. Omitting colour update information, small position errors of objects denoted as geometrical distortions are allowed for image synthesis instead of quantization error distortions. Tolerating geometrical distortions, the image area to be updated by colour coding can be decreased to 4% of the image size without introducing annoying distortions. As motion and shape parameters can efficiently be coded, about 1 bit per pel remains for colour updating in a 64 kbit/s coder compared to about 0.1 bit per pel in the standard reference coder (RM8) of the CCITT. Experimental results concerning the efficient coding of motion and shape parameters are given and discussed. The coding of the colour information will be dealt with in further research.     

Low complexity shape-adaptive DCT for coding of arbitrarily shaped image segments

A low complexity shape-adaptive DCT transform algorithm for coding pels in arbitrarily shaped image segments is presented. The proposed algorithm is compared to the well established generalized shape-adaptive transform method introduced by Gilge et al. in terms of transform efficiency and computational complexity. Results obtained under both theoretical and experimental conditions show that the new algorithm achieves a transform efficiency close to that of the Gilge method with considerably reduced computational complexity. The proposed shape-adaptive DCT algorithm was implemented into a standard MPEG-1 coder to provide object or segment based coding of images and video with additional content-based functionality. The extended MPEG-1 object based coding scheme can handle generic input sequences and can readily provide MPEG-1 backward compatibility if no contour data is transmitted for a given video sequence. Results for INTRA coding of images indicate that the algorithm allows efficient coding over a wide range of coding parameters — thus providing means for generic coding of segmented video between very high and very low bit rates. It is further shown that some of the content-based based functionalities currently discussed in MPEG-4 can be provided efficiently using the proposed object based coding scheme.