动态扩容视频存储分发系统设计

在带宽增速,互联网用户对视频内容的要求日趋增多的趋势下,本文描述了大规模视频存储分发的系统设计和实现.该系统设计的目标是把用户上传的视频重新编解码生成适合不同场景的不同格式视频文件,然后根据客户端支持的视频属性和网络带宽的实际情况,自动分发不同码流的视频文件到客户端,从而达到流畅访问视频的目的;对系统中的热门视频,系统通过算法结合缓存,实现同一视频文件在不同服务器间动态迁移,从而充分利用系统的计算能力,最终给用户提供更流畅的视频体验.     

视频监控系统内外网同时访问设计

通过在矿区视频监控使用时遇到的内外网不能同时访问视频信号的问题,提出了利用视频监控系统中管理服务器添加内外网两个区域,分别给不同网段用户相应权限;通过防火墙静态映射,把管理服务器和流媒体服务器映射到外网中,实现内外网用户同时访问流媒体视频监控系统的目的,通过实际应用,取得了良好的效果.     

基于嵌入式Linux和Qt的交通信息采集系统

文章所介绍的基于视频图像处理的交通信息采集系统,包含视频采集卡、交通信息采集终端和远程服务器三大部分,系统软件在Linux和Qt用户环境下开发完成,具有实时性好、算法高效等特点。     

基于FFMPEG的嵌入式视频监控系统

随着计算机技术的飞快发展,网络视频监控已经成为视频监控领域最重要发展方向,网络视频监控系统最早出现于2001年,网络化的嵌入式视频监控系统不受时间和空间的限制,本身可以做为视频流媒体服务器,突破了监控的时空限制,使客户端用户通过网络中的任何一台电脑来观看、录制和管理实时的视频信息。     

浅谈VOD服务器的安装与测试

随着时代的进步，人们对视频节目服务提出了更高的要求，希望改传统的被动观看为主动控制。能实现对视频节目的内容、播放时间和播放进度等诸多方面进行选择和控制。视频点播就是为了满足人们这种需求而产生的一种服务方式。近年来，随着高速计算机、数字视频压缩以及大容量存储器的发展，视频点播（Videoon—Demand）服务成为可能。一个典型的视频点播系统是由视频服务器、高速传输网络和客户端组成。服务器响应用户的点播请求．将节目数据以视频流的形式通过高速传输网络发送到用户端。视频服务器是整个视频点播系统的核心部分．选择和安装性价比高的视频服务器是构建视频点播系统的关键。图1所示是一个典型的VOD的系统结构。     

基于微信公众平台的视频答疑平台开发与应用

公众平台是微信支持特定用户为普通用户提供信息服务的工具,基于微信公众号的信息传播和发布已经成为一种流行的信息发布模式。开发基于微信公众号的视频答疑平台能够最大限度的提高平台的适用性。但是微信公众平台对上传的视频大小有限制,不便于老师对知识点进行完整的解释。为了解决这个问题,设计了一种微信公众平台和专用视频服务器相结合的视频答疑模式。这种服务模式一方面可以保证系统使用的便利性,另一方面也可以提高视频的稳定性。通过在本科生教学中推广该视频答疑平台的效果,可以看出该答疑模式得到了广大师生的认可和肯定。     

新的战略方向——网上视频协作

最近,PictureTel公司宣布了公司的新的战略方向--网上视频协作(VCN).VCN综合了PictureTel全系列视频协作产品和服务、新兴宽带IP网络质量和遍布全球的因特网的优点,可以为全球客户提供以网络为基础的商用级视频协作产品和服务. (1)VCN的实现 VCN是以网络为核心,基于Web的视频协作策略.从现场实时的电视会议和视频流会议、信息通报和广播的传输,到以流形式对电视会议进行存档、检索,以备日后重播,VCN将视频协作的便利带给了全球客户.有了VCN,客户不必在技术管理上耗时费力便可以充分利用视频协作.这一基于网络的简单方法可以使用户全身心地投入到工作中,而不必考虑可视会议或其他视频协作技术的操作.     

基于P2P网络流媒体直播系统研究与设计

主要讨论了一种基于P2P网络的流媒体直播的相关技术,研究设计了一个支持大量用户同时在线的直播系统方案,能够充分利用客户端资源,减轻服务器负载,并实现较好的视频直播效果,该系统采用了P2P传输技术,系统的可扩展性和稳定性都明显优于传统流媒体视频传输系统.     

嵌入式视频监控系统视频服务器的设计与实现

提出了基于AT91RM9200微处理器的嵌入式Linux视频监控系统[1]的视频服务器设计方法.采用韩国Pentamicro公司的视频芯片AT2042对数字视频数据进行MPEG-4压缩编码,生成MPEG-4码流.为实现交互性的要求,在嵌入式WEB服务器中采用CGI技术,对远程监控端的控制信息分析处理,实现B/S模式的交互功能和系统的远程控制.与传统的设计方法相比,该系统视频图像的质量得到改进,开发便捷,成本低廉,应用范围广.     

一种基于H.264监控视频的快速检索系统

介绍了一种基于H.264格式压缩的监控视频检索系统,该系统基于对象和语义,主要包括视频分析和视频检索两大模块.通过视频分析模块,对H.264压缩域视频解码并进行视频对象提取、分割、特征提取和对象匹配等分析过程,将得到的视频对象及特征信息存入至对象特征数据库;在视频检索模块端,用户可以通过输入语义信息或示例图片直接从特征数据库中进行视频检索查询,避免了视频的重复处理.实验表明,通过提出的系统可以快速有效地进行视频检索.     

A Hybrid Video-on-Demand Data Broadcasting and Receiving Scheme of Harmonic and Staggered Schemes

In providing video-on-demand (VoD) services to a number of clients through networks, the bandwidth requirements of video transmission restrict VoD services. For this reason, many significant broadcasting-based VoD schemes have been proposed to efficiently support services. However, the broadcasting-based VoD schemes approach needs frequency channel hopping, using many channels at the same time and managing many segments of a video. These make it difficult to implement. In this paper, we propose a harmonic staggered broadcasting scheme which has a simple structure and substantially improved VoD efficiency. The proposed scheme substantially reduces the number of segments required and the frequency for switching channels. Also this new scheme performs significantly better than the existing VoD schemes in viewer's waiting time and buffer requirements with simplicity. The numerical results demonstrate that the viewer's waiting time of the harmonic staggered broadcasting scheme is close to the harmonic broadcasting scheme and the buffer requirements of this can be adjusted by a video dividing coefficient $h$ .      

A scalable video-on-demand system using multi-batch buffering techniques

A video-on-demand (VoD) system delivers videos on demand over an installed network. Due to the large size of digitized videos, expensive video servers with high I/O capability are needed in order to provide VoD services in metropolitan areas. In addition, there is a great need for efficient networking distribution/interaction schemes so that the video servers can serve as many clients as possible. In particular, because of scalability problems, the classical unicast VoD system is not suitable for large-scale deployments. In this paper, a highly scalable VoD system with a low per-user cost is described and evaluated. We first analyze the performance degradation problems using recently proposed VoD systems, namely batched and centralized-buffer VoD systems that occur during the handling of interactions. Then a new system called the multi-batch buffer (MBB) system, which attempts to solve these problems, is proposed. The proposed system handles a majority of interaction requests by scalable buffering techniques employed in the buffer of the local servers and the set-top boxes (STB). We have performed extensive simulation for the analysis and performance evaluation of our proposed VoD system. The simulation results demonstrate that our VoD system is very scalable and outperforms related state-of-the-art VoD systems.     

CAR: a low latency video-on-demand broadcasting scheme for heterogeneous receivers

As different types of wireless networks are converging into an all-IP network, i.e., the Internet, it can be expected that in the near future video-on-demand (VoD) will be widely applied to many interesting services, and users can access these services using heterogeneous terminals via heterogeneous wired/wireless access networks. Many periodic broadcasting protocols have been proposed to reduce the implementation cost of VoD systems. However, most of the protocols assumed homogeneity for user terminals, while in practice, user terminals are usually quite different in their processing power, buffer space, and power. To address this problem, a few periodic broadcasting protocols providing the same video quality for all heterogeneous clients have been proposed recently. In this paper, we proposed a novel heterogeneous VoD broadcasting technique called Catch and Rest (CAR) to accommodate bandwidth heterogeneity without sacrificing user video quality. Then, we provide mathematic analysis to calculate the client bandwidth and buffer space requirements of CAR. Finally, we present our performance evaluation results for CAR. Our results show that under the same system resources (i.e., server and network bandwidth), CAR provides more uniform and acceptable service latency for all heterogeneous clients compared to previous works.     

视频失真优化的分布式视频点播服务系统及性能分析

本文提出一种用于分布式视频点播服务系统的速率分配算法和实现框架。在考虑负载均衡与满足服务器带宽限制的前提下,速率分配能将以失真为度量的全局视频质量最优化。确定各服务结点的输出码率被建模成一个最优化问题：优化目标是最小化多个视频总失真,限制条件为最低可接受视频质量、服务器带宽限制以及发送速率对客户端TCP流量的友好性。根据优化算法的计算结果,视频节目使用可变码率编码,由多个视频分发服务器同时向客户端传输;同时服务器检测与客户端之间端到端链路的时变特性和估计网络拥塞情况,使优化速率分配结果适应网络状态的变化。本方案应用跨层设计的思想,将应用层视频质量建模为网络层参数的函数,当网络状态波动时,动态调整编码码率和发送速率以适应带宽变化,提前避免链路拥塞,降低接收端解码器丢包率,从而使总体视频质量得到提升。     

Modeling and application of moderate prefetching strategy based on video slicing for P2P VoD systems

In peer-to-peer (P2P) video-on-demand (VoD) streaming systems,each peer contributes a fixed amount of hard disk storage (usually 2 GB) to store viewed videos and then uploads them to other requesting p...     

分布式VoD系统的分级存储调度

提出了一种适于大规模分布式ＶｏＤ系统的分级存储调度算法。该算法建立在多队列的排队模型之上,使用上系统均衡方法及基于优先级的缓冲区管理算法,并提供了迁移等待时间的计算方法。通过仿真实验给出了缓冲区大小与业务量和节目驻留时间的关系,为ＶｏＤ分级存储系统的设计提供了依据。     

基于分布式缓存管理架构的P2P VoD系统

针对P2PVoD系统中怎样有效地管理和使用节点所缓存的媒体内容的问题,本文提出了一种基于分布式的缓存管理架构。在这一架构中每个节点存储系相应的媒体分块,所存储的媒体分块可以组合成一个完整的媒体文件的所有节点分布在一个环内。因此在一个环内可以快速定位到这个媒体文件的不同分块,提高了资源搜素的效率。仿真证明这种架构可以有效地管理和使用节点所缓存的媒体内容支持用户的VCR操作。     

基于代理的分布式视频流点播传输策略

视频流传输具有带宽高、周期长的特点,使网络带宽成为了制约视频流点播应用发展的主要因素.本文针对现有网络技术条件,充分利用客户端I/O带宽、本地缓存及网络带宽资源,设计了一个适用于大规模点播应用的基于代理的分布式视频点播传输策略.该策略中各本地网络设有一视频流代理服务器用于保存部分视频的部分内容,并按动态批处理的方式来接纳并服务请求用户.视频传输时,服务器与代理端之间采用单播传输机制,在代理与客户端之间采用单播与多播相结合的方式.实验表明该策略可以大大减少对骨干网络带宽的需求,并能为客户端提供理论上的零启动延时服务.     

Cache Optimization on Hot‐Point Proxy Caching Using Weighted‐Rank Cache Replacement Policy

The development of proxy caching is essential in the area of video‐on‐demand (VoD) to meet users' expectations. VoD requires high bandwidth and creates high traffic due to the nature of media. Many researchers have developed proxy caching models to reduce bandwidth consumption and traffic. Proxy caching keeps part of a media object to meet the viewing expectations of users without delay and provides interactive playback. If the caching is done continuously, the entire cache space will be exhausted at one stage. Hence, the proxy server must apply cache replacement policies to replace existing objects and allocate the cache space for the incoming objects. Researchers have developed many cache replacement policies by considering several parameters, such as recency, access frequency, cost of retrieval, and size of the object. In this paper, the Weighted‐Rank Cache replacement Policy (WRCP) is proposed. This policy uses such parameters as access frequency, aging, and mean access gap ratio and such functions as size and cost of retrieval. The WRCP applies our previously developed proxy caching model, Hot‐Point Proxy, at four levels of replacement, depending on the cache requirement. Simulation results show that the WRCP outperforms our earlier model, the Dual Cache Replacement Policy.