一种基于同心圆切割的XML编码方案

在可扩展标记语言(XML)文档的查询过程中,为快速判断任意两节点关系,提出一种基于同心圆切割的编码方案.将一棵n层的XML树看作由n个不同半径的同心圆组成,圆心代表根节点,根据兄弟节点等分切割给定区域的思想,将圆半径、角度与标识相结合进行编码.实验结果表明,与DietZ和StratE编码方法相比,该方案可加快节点间关系判断及任一节点在文档中具体定位的速度,时空效率较高.     

基于对象的视频编码技术

首先介绍了视频对象的分割技术,然后着重对视频对象编码的相关问题进行了分析和阐述,包括典型的形状编码方法,对纹理编码、形状和纹理数据的运动估计以及任意形状视频对象的可扩展编码等问题进行了分析;最后介绍了视频对象编码中的比特分配问题.     

基于向量的动态XML编码方法研究

基于向量的动态可扩展标记语言(XML)编码方法计算简单,但不能对已删编码进行重用,严重影响XML更新效率。为此,利用Stern-Brocot树对中间向量计算进行改进,提出一种求解最短位长中间向量的多项式时间算法,对批量分配进行优化,从而提高向量编码的更新性能。实验结果证明改进的编码方法能较好地重用已删编码,适用于XML的频繁更新。     

XML数据扩展前序编码的更新方法

大部分XML查询技术都是基于某种对XML树的编码方法.对XML树的编码,是指按照某种规则对XML树的每一个结点分配唯一的编码,目的是通过任意两个结点的编码,能够直接判断两个结点之间是否具有祖先后代关系.最常用的编码方法是区域编码方法(region based numbering scheme).然而,XML数据也会面临插入删除等更新问题.数据一旦更新,区域编码也要作相应的调整,才能保证基于这个编码的各种索引和查询算法的正确性.在编码的更新方面,目前研究得还不多.主要研究区域编码的更新问题,采用预留编码空间的方法,针对不同特征的XML数据和应用环境提出了一整套预留算法和编码更新算法,并做了大量的实验,检验这些算法的有效性.     

视频细粒度可分级编码的研究

本文对提高传输视频流质量有很大贡献的视频细粒度可分级编码方法进行了研究分析。首先介绍了MPEG-4 FGS的基本思想和可扩展特性;接着介绍了H.264 FGS的基本原理,最后介绍了具体的应用。     

XML数据更新编码机制——ITBI

编码技术是可扩展标记语言(XML)查询处理的基础,传统编码技术利用自然数进行编码,很难支持XML动态更新。提出了更新支持的编码方法——ITBI,该方法将整数映射到完全二叉树,利用二叉树的中序遍历定义整数新的序关系,通过新的序关系重排自然数序列将静态编码转化为动态编码。同时,基于ITBI前驱、后继、距离等定义,设计了最短位长动态编码分配算法,有效控制更新过程中编码位长的增加。最后通过实验验证了编码的有效性。     

形状编码技术研究进展

主要对各种形状编码技术的原理、特点、压缩效率、可分级传输及软硬件实现复杂度等方面进行总结归纳,为研究更好的形状编码方法提供了一些思路.     

XML 动态区间编码方法

提出了适用于XML文档更新环境下的区间编码方法——DCLS(dynamic containment labeling scheme).DCLS将基于整数的编码泛化到基于向量的编码,扩展了传统静态区间编码方法,有效避免了XML文档更新时的重新编码.不论文档更新与否,DCLS都显示了良好的性能:DCLS利用基于整数的静态区间编码方法进行初始编码,在文档不更新的环境下,具有较高的存储效率和查询性能;同时,DCLS将整数视为特殊向量,不仅能够支持文档更新,而且更新效率高;特别是倾斜插入时,DCLS可以避免编码位长的快速增加.实验结果表明,与已有的动态区间编码方法相比,DCLS具有更好的性能.     

空域精细可扩展编码预处理器的设计和实现

为了更好地运用空域精细可扩展编码算法,提出了一种编码预处理器的设计方案。该方案占用较少的外部存储空间缓存帧数据,充分利用数据操作之间的并行性和流水性,生成视频数据的多描述码流。仿真结果表明,该方案能满足空域精细可扩展编码算法的功能和实时性要求。     

采用高维路由节点构建直连式可扩展路由器

可扩展路由器是当前核心路由器研究的热点,直连式可扩展路由器是可扩展路由器研究的一种重要分支.但是,目前直连式可扩展路由器的研究局限于采用低维路由节点的方式进行扩展,这种方式构建的路由器其可扩展互连结构的网络直径增长较快而等分带宽增长较慢.针对该问题,提出采用高维路由节点构建直连式可扩展路由器的思想,认为构建直连式可扩展路由时,路由节点的维要根据路由节点的交换容量和分组延时决定.在分组延时小于某个界的情况下,路由节点的交换容量越大它的维也应该越高这样才能使路由器的可扩展互连结构有最大的等分带宽和最小的网络直径,使路由器在满足分组延时要求的情况下具有最大的交换容量.从理论上分析了该思想的可行性,仿真结果进一步验证了理论分析的正确性.     

基于感兴趣区域的小波变换可分级视频编码研究

随着Internet和无线通信的飞速发展,人们在网络上实时获取视频数据已经成为可能。由于传输网络和接收终端的多样性,所以需要视频流能适应多种不同传输、解码和显示的要求,由此产生了可分级视频编码。文中在可分级视频编码的基础上对其进行改进,把感兴趣区域的检测和小波变换应用到可分级编码中,该方法中对视频流进行感兴趣区域检测,利用小波变换对增强层中的感兴趣区域进行编码,由于小波变换具有良好的空间方向选择性,与人眼的视觉特性十分吻合,从而得到很好的效果。     

一种基于内容的图像空间可分级编码方案

图像可分级编码和基于内容的编码机制作为新一代图像编码的两个重要目标，越来越受到人们的重视。本文以小波作为工具提出一种基于内容的图像空间可分级编码方案，该方案首先对图像的ROI(Regions of Interest)进行了一种基于ROI“包围盒”和ROI边界对称延拓的小波分解，然后对各子带进行阶梯形量化，并按子带的重要性顺序对各子带的系数进行重排，最后对重排系教进行熵编码，从而形成适应于ROI空间可分级解码需求的码流，试验结果验证了方案的有效性。     

On the impact of the GOP size in a temporal H.264/AVC-to-SVC transcoder in baseline and main profile

Scalable video coding is a recent extension of the advanced video coding H.264/AVC standard developed jointly by ISO/IEC and ITU-T, which allows adapting the bitstream easily by dropping parts of it named layers. This adaptation makes it possible for a single bitstream to meet the requirements for reliable delivery of video to diverse clients over heterogeneous networks using temporal, spatial or quality scalability, combined or separately. Since the scalable video coding design requires scalability to be provided at the encoder side, existing content cannot benefit from it. Efficient techniques for converting contents without scalability to a scalable format are desirable. In this paper, an approach for temporal scalability transcoding from H.264/AVC to scalable video coding in baseline and main profile is presented and the impact of the GOP size is analyzed. Independently of the GOP size chosen, time savings of around 63 % for baseline profile and 60 % for main profile are achieved while maintaining the coding efficiency.     

An End-to-End Embedded Approach for Multicast/Broadcast of Scalable Video over Multiuser CDMA Wireless Networks

We investigate an embedded multicast/broadcast approach for transport of digital video over spread-spectrum code-division multiple access (CDMA) cellular networks. Previous work has shown that the incorporation of a scalable source coding scheme with multiresolution modulation provides a promising design paradigm for the practical realization of the information-theoretic performance predictions originally developed by Cover, which demonstrated that optimal multicast/broadcast performance could be achieved by an embedded transmission scheme. Hence, the major technical challenge associated with the design of an end-to-end embedded multicast/broadcast system is how to match an embedded modulation constellation with a scalable source coding scheme. In this work, taking into consideration both the interference-limited and bandwidth-limited characteristics of a CDMA system, we provide a cross-layer approach incorporating adaptive power allocation and channel coding strategies and effectively match a discrete cosine transform based scalable motion-compensated video encoder to an embedded multiresolution modulation scheme to simultaneously deliver a basic quality-of-service (QoS) to less capable receivers while maximizing both the QoS for more capable receivers and the system capacity. We demonstrate the efficacy of this approach using the ITU-T H.263+ video scalable hybrid coder, although the approach is generally extensible to other scalable coding schemes as well     

Scalable video traffic offloading for streaming services in 5G HetNets

Multimedia Tools and Applications - In this paper, by combining scalable video coding (SVC) and traffic offloading, we propose a scalable video traffic offloading (SVO) approach to provide video...     

Two-Dimensional Channel Coding Scheme for MCTF-Based Scalable Video Coding

The motion-compensated temporal filtering (MCTF)-based scalable video coding (SVC) provides a full scalability including spatial, temporal and signal-to-noise ratio (SNR) scalability with fine granularity, each of which may result in different visual effect. This paper addresses a novel approach of two-dimensional unequal error protection (2D UEP) for the scalable video with a combined temporal and quality (SNR) scalability over packet-erasure channel. The bit-stream is divided into scalable subbitstreams based on the structure of MCTF. Each subbitstream is further divided into several quality layers. Unequal quantities of bits are allocated to protect different layers to obtain acceptable quality video with smooth degradation under different transmission error conditions. Experimental results are presented to show the advantage of the proposed 2D UEP scheme over the traditional one-dimensional unequal error protection (1D UEP) scheme. Comparing the proposed method with the 1D UEP scheme on SNR layers, our method gives up to 0.81-dB improvement for some video sequences     

空间可扩展视频编码中增强层上的帧内预测算法研究

针对空间可扩展视频编码,提出了一种新的增强层上的帧内预测算法。该算法充分考虑了相邻层间所固有的空域相关性,在无法正确获取本层邻块预测值的情况下,利用基本层上插值放大后的解码,通过重构宏块来对增强层上的编码宏块进行帧内预测。此外,还在预测过程中,通过引入与图像纹理特征相关联的自适应加权因子对(Wv,Wh)来进一步提高新算法的编码性能。实验结果表明,与H.264标准中的帧内预测算法相比,新算法在保持原有码率和不增加额外的计算复杂度的前提下,可一定程度地提高亮度分量的PSNR值,因此可以作为空间可扩展视频编码中增强层上的帧内编码方案。     

An algorithm for interest management in High Level Architecture

One of the most important design concerns when implementing large-scale high-level architecture (HLA) simulations is how to perform effective interest management. HLA interest management separates routing from data delivery so as to filter out unnecessary data communication between federated computers. One of the more scalable mechanisms for such interest management, data distributed management (DDM), distributes and filters data based on regional clustering. Essential to DDM, therefore, are the algorithms for dividing routing space and for matching regions. In this article, we describe how the spatial hierarchy of routing space is defined, and introduce a technique based on n-dimensional binary trees to solve the problem of region matching. We then introduce two algorithms: one to compute the coding of hierarchically structured regions, and the other to match regions based on this coding. Finally, we outline our general strategy for data filtering in HLA, and analyze the advantageous and limitations of the algorithm through experiments.     

Interactive region of interest scalability for wavelet based scalable video coder

The current wavelet-based scalable video coder supports quality, spatial and temporal scalabilities required for recent multimedia applications. One of the key scalability required by the Joint Video Team (JVT) is Interactive Region of Interest (IROI) scalability. This paper proposes a technique to interactively extract ROI from scalable sub bit-streams. At the encoder, after sub-band decomposition the 3D wavelet tree is divided into N sub tree, each of these has spatial relevance in the original video, which can be decoded interactively. A generalized model for optimal value of N is proposed, that satisfies minimum requirement of the JVT about IROI support at reduced cost of the encoder. The ROI request from decoder along with resolution and bandwidth are mapped to that in the sub-band domain and respective sub-bit-streams are identified. The extractor assigns more bandwidth to ROI and remaining to non-ROI regions. Hence the decoder reconstructs the video with highest quality at the ROI. The proposed IROI functionality enhances the scalability of video coding by additional dimension.