一种新型VOD系统视频服务器的设计

本文提出了一种带有新颖的视频流分配方案的可伸缩ＶＯＤ系统视频服务器的设计方案,从系统的体系结构方面充分探讨了如何使用单个主机处理越来越多的同时发生的视频点播要求,以及如何利用视频节目的分配文件的存贮特性减少磁盘寻道行为。本文将详细讨论直流视频流泵、磁盘子系统的文件释放策略以及系统的可伸缩性。     

VOD视频服务器中的视频流调度策略

介绍了视频服务器中的几种视频流调度策略,并在此基础上给出了一种新的调度策略。     

基于集群的VOD系统视频服务器的负载均衡算法改进

文章针对VOD视频服务中不同的点播方式和视频文件存储调度的特点等问题,改进了三种负载均衡算法-加权最少连接算法、视频服务节点负载排名算法以及视濒文件播放信息算法。     

视频服务器设计关键技术分析

文章分析了VOD系统视频服务器的组成部分。在总结已有研究成果的基础上,重点从应用层的角度刻画了设计的要点;并根据技术发展的趋势,提出了将来需要关注的方面。     

视频点播(VOD)及其在Internet上的实现

在宽带网的建设和流媒体技术进步的背景下,视频点播得以迅速发展.VOD系统的核心是视频服务器,通过B/S结构,用户可以在客户端的浏览器窗口与视频服务器进行交互,在嵌入式播放器中观赏和控制视频.     

可扩展的VOD服务器系统

提出了分布式可扩展的VOD系统结构，扩展性的研究能够提供更多的并发流服务。从系统结构及工作流程、基于CORBA的通讯、负载均衡及存储技术等方面论述了系统的扩展性。测试结果表明，该系统可以适应不同规模的VOD应用。     

VOD视频服务器测试与配置优化研究

视频服务器是VOD系统的核心.本文采用软硬件协同测试的观点对视频服务器的主要性能环节进行了测试分析,总结出了一些经验规律,给出了把通用PC服务器优化配置为视频服务器的方法和实例.     

基于Web的VOD服务器的设计与实现

VOD(Video On Demand)即视频点播,是随着计算机技术和网络通信技术的发展,综合了计算机、通信技术、电视技术而迅速新兴的一门综合性技术。介绍了流媒体技术的基本概念,基本主流技术,VOD系统的基本结构及工作原理以及实现的过程,设计出一种基于Web的VOD服务器,实现视频点播。     

VOD服务器设计的支撑技术

本文从连续媒体数据分布、磁盘调度和回取控制、缓存控制、允许控制与内资源分配、带平滑、可扩展性和交互等多方面对视频服务器性能影响很大的支撑技术进行了讨论。     

Storage and retrieval methods to support fully interactive playout in a disk-array-based video server

One of the most important challenges in a videoon-demand (VOD) system is to support interactive browsing functions such as fast forward and fast backward. Typically, these functions impose additional resource requirements on the VOD system in terms of storage space, retrieval throughput, network bandwidth, etc. Moreover, prevalent video compression techniques such as MPEG impose additional constraints on the process since they introduce interframe dependencies. In this paper, we devise methods to support variable rate browsing for MPEG-like video streams and minimize the additional resources required. Specifically, we consider the storage and retrieval for video data in a diskarray-based video server and address the issue of distributing the retrieval requests across the disks evenly. The overall approach proposed in this paper for interactive browsing is composed of (1) a storage method, (2) sampling and placement methods, and (3) a playout method, in which the sampling and placement methods are two alternatives for video-segment selection. The segment-sampling scheme supports browsing at any desired speed while balancing the load on the disk array, as well as minimizing the variation on the number of video segments skipped between samplings. In contrast, the segment-placement scheme supports completely uniform segment sampling across the disk array for some specific speed-up rates. Several theoretical properties for the problem studied are derived. Finally, we describe experimental results on the visual effect of the proposed frame-skipping approach.     

嵌入式数字视频监控系统通用存储与检索方案

为了解决现有的嵌入式数字视频监控系统的多路视频存储与检索的结构差异,从而严重制约视频监控系统的可复用性与引起系统I/O瓶颈问题,提出一种嵌入式数字视频监控系统通用存储与检索方案.采用组件化思想构建视频存储与视频检索模块,通过设计存储调度算法减少了I/O瓶颈问题,使用检索控制策略降低了检索拥塞.与以前的系统相比在支持多路视频存储与检索方面表现出改进的性能,同时具有更好的可重用性.     

基于内容检索的视频分割技术的研究

视频分割就是从视频序列中分割出在语义上有意义的对象。目前，视频分割已从基于镜头的分割发展到了基于内容的视频对象分割。文章介绍了基于内容的时域及空域视频分割技术，提出了一种基于多帧差异的视频对象分割算法。     

基于VxWorks的嵌入式网络视频服务器设计

网络视频服务器是一种嵌入式数字远程监控系统，它集视频采集、实时压缩和网络传输等功能为一体，本文提出了基于VxWorks平台的网络视频服务器的实现方案，在介绍实时操作系统Vxworks和MPC860T的基础上，结合音视频编解码芯片AT2042，给出了网络视频服务器的软、硬件实现方法。     

视频点播系统中的节目调度

节目调度问题是视频服务器设计和实现中的一个重要问题 ,优化的节目调度和节目管理可以极大的提高视频服务器的性能 .本文对视频服务器的节目调度方案进行了简要归纳 ,然后提出一种节目调度方案的优化使用方法 .理论分析表明 ,这种方法可以有效的节省服务器的资源 ,提高服务器的服务水平 .     

Buffer-Sharing Techniques in Service-Guaranteed Video Servers

Advances in networking and storage technology have made it possible to deliver on-demand services over networks such as the emerging video-on- demand (VOD) applications. Although a variety of studies have been focused on designing video servers suitable for VOD applications, the number of concurrent on-demand services supported by such servers is often limited by the I/O bandwidth of the storage systems. Recently, several researchers have focused on providing guaranteed services instead of on-demand services in a VOD system. A service is said to be guaranteed if every viewer can be served within a specified waiting time after the video has been subscribed. This paper describes a model called a buffer-sharing autonomy, which combines batching and bridging techniques to provide guaranteed services to VOD systems. We also describe how buffer-sharing techniques can be used in this model to provide the same services with fewer buffer resource through the use of playback-rate alteration. Additionally, in order to make buffer sharing efficient, it is important to group appropriate video streams together to share buffer resource. Four grouping policies are proposed for this purpose and the benefits yielded are also analyzed and compared. Finally, the results of our experiments show that the proposed buffer-sharing techniques promise the provision of guaranteed video services at low cost.     

Disk placement for arbitrary-rate playback in an interactive video server

Multimedia data, especially continuous media including video and audio objects, represent a rich and natural stimulus for humans, but require large amount of storage capacity and real-time processing. In this paper, we describe how to organize video data efficiently on multiple disks in order to support arbitrary-rate playback requested by different users independently. Our approach is to segment and decluster video objects and to place the segments in multiple disks using a restricted round-robin scheme, called prime round-robin (PRR). Its placement scheme provides uniform load balance of disks for arbitrary retrieval rate as well as normal playback, since it eliminates hot spots. Moreover, it does not require any additional disk bandwidth to support VCR-like operations such as fast-forward and rewind. We have studied the various effects of placement and retrieval schemes in a storage server by simulation. The results show that PRR offers even disk accesses, and the failure in reading segment by deadline occurs only at the beginning of new operations. In addition, the number of users admitted is not decreased, regardless of arbitrary-rate playback requests.     

流媒体视频存储服务器设计与研究

详细分析了在视频监控系统中流媒体视频存储服务器的作用和功能,针对传统的流媒体定时长存储方式的不足提出了固定空间存储的新策略.该存储策略将总空间初始化为多个固定大小的数据文件,每个数据文件中存储的流媒体时长可能是不相同的.针对新存储策略下出现的1秒尾巴,事件尾巴等新问题,提出了解决方案.固定空间存储策略虽然增加了索引的复杂度,但是有效避免了磁盘碎片的产生,对于改善流媒体视频存储服务器性能具有重要作用.     

VisionGo: Towards video retrieval with joint exploration of human and computer

This paper introduces an effective interactive video retrieval system named VisionGo. It jointly explores human and computer to accomplish video retrieval with high effectiveness and efficiency. It assists the interactive video retrieval process in different aspects: (1) it maximizes the interaction efficiency between human and computer by providing a user interface that supports highly effective user annotation and an intuitive visualization of retrieval results; (2) it employs a multiple feedback technique that assists users in choosing proper method to enhance relevance feedback performance; and (3) it facilitates users to assess the retrieval results of motion-related queries by using motion-icons instead of static keyframes. Experimental results based on over 160 h of news video shows demonstrate the effectiveness of the VisionGo system.     

VOD系统关键技术研究

文章介绍了VOD系统的类型并重点分析了视频点播系统中的关键技术。在总结已有研究成果的基础上。从视频服务器结构设计的角度提出了将来需要关注的方面。