Video Decompression Estimation and Playout Scheme Over the Internet

This paper examines problems associated with display of live continuous media. Under the assumption that the network cannot guarantee the required bounds on delay and jitter and the operating system scheduling is non-realtime, there is a need to accommodate the delay and jitter in the end systems in order to maintain a desirable Quality of Service (QoS). We propose a method of video playback which requires accurate estimation of display cycle time of video frames and the delay suffered by frames in the packet network. We apply various deterministic forecasting methods used in time series analysis on experimental data collected from video transmission. Suitable methods are recommended for display cycle time and delay estimation.     

Design and Experimental Evaluation of an Adaptive Playout Delay Control Mechanism for Packetized Audio for Use over the Internet

We describe the design and the experimental evaluation of a playout delay control mechanism we have developed in order to support unicast, voice-based audio communications over the Internet. The proposed mechanism was designed to dynamically adjust the talkspurt playout delays to the traffic conditions of the underlying network without assuming either the existence of an external mechanism for maintaining an accurate clock synchronization between the sender and the receiver during the audio communication, or a specific distribution of the audio packet transmission delays. Performance figures derived from several experiments are reported that illustrate the adequacy of the proposed mechanism in dynamically adjusting the audio packet playout delay to the network traffic conditions while maintaining a small percentage of packet loss.     

多媒体通信中的一种视频平滑方案

多媒体通信中一个很重要的服务质量指标就是视频数据传输的平滑度,但平滑度往往是与网络传输流量相矛盾的.文章正是针对这一矛盾,通过引入控制论的思想并利用神经网络预测流量的特征参数,提出了一种解决多媒体通信中视频数据流平滑的方案.通过实验模拟,证明了该方案能很好地解决多媒体通信中的这一矛盾,使视频流量和平滑度折衷后达到最优效果.     

存储视频带宽平滑算法的研究比较

文章综述了存储VBR视频带宽平滑的各种算法,比较了这些算法的各自特点,归纳、形式化了这些算法模型的更一般化表示。     

Frame Selection for Dynamic Caching Adjustment in Video Proxy Servers

By caching video data, a video proxy server close to the clients can be used to assist video delivery and alleviate the load of video servers. We assume a video can be partially cached and a certain number of video frames are stored in the proxy server. In our setting, the proxy server is allowed to cache the passing data from the video server. A video provides several options (levels) in terms of bandwidth requirement over the server-proxy path. For each video, the proxy server decides to cache a smaller amount of data at a lower level or to accumulate more data to reach a higher level. The proxy server can dynamically adjust the cached video data by choosing an appropriate level based on the network condition or the popularity of the video. We propose a frame selection scheme, Dynamic Chunk Algorithm, to determine which frames are to be cached in the proxy server for the dynamic caching adjustment scenario. The algorithm guarantees the rate constraint over the server-proxy path to be satisfied for each level. This approach also maintains the set of cached frames at a higher level as a superset of the cached frames at a lower level. Hence, it enforces the proxy server to simply cache more data without dropping frames when it intends to reduce network bandwidth consumption for a video and vice versa.     

VBR视频流磁盘I/O的平滑调度算法

文章将带宽平滑技术引入磁盘 I/ O调度 ,基于现已取得的研究成果 ,考虑磁盘 I/ O存取特性 ,提出一个针对VBR视频检索的整数块平滑调度算法 .算法所得的结果被证明是优化的 ,实验结果显示该算法在磁盘空间和磁盘 I/ O的带宽利用方面有很好的性能     

基于漏斗的实时VBR视频最短路径平滑算法①

针对实时VBR视频流式传输的在线平滑优化问题,提出一种基于漏斗的最短路径平滑算法——SPSF。SPSF利用滑动窗口对实时VBR视频进行分段处理,顺序读取和缓存每帧视频数据至窗口,并基于漏斗原理求解窗口内数据的最短路径。数据填满窗口后根据求得的最短路径进行传输,同时根据路径特征推进窗口滑动进行下一段数据的平滑处理及传输,以此类推完成整个视频平滑传输。实验结果表明,与传统的在线平滑算法相比,SPSF具有更优的传输比特率峰值、传输比特率谷值、及传输比特率方差;与传统的最短路径算法相比,SPSF具有更快的最短路径     

基于漏斗的实时VBR视频最短路径平滑算法①

针对实时VBR视频流式传输的在线平滑优化问题,提出一种基于漏斗的最短路径平滑算法——SPSF。SPSF利用滑动窗口对实时VBR视频进行分段处理,顺序读取和缓存每帧视频数据至窗口,并基于漏斗原理求解窗口内数据的最短路径。数据填满窗口后根据求得的最短路径进行传输,同时根据路径特征推进窗口滑动进行下一段数据的平滑处理及传输,以此类推完成整个视频平滑传输。实验结果表明。与传统的在线平滑算法相比,SPSF具有更优的传输比特率峰值、传输比特率谷值、及传输比特率方差;与传统的最短路径算法相比,SPSF具有更快的最短路径求解速度,提高了视频传输的实时性。     

An Algebraic QoS-Based Resource Allocation Model for Competitive Multimedia Applications

A new class of multimedia applications require new mechanisms to consider various Quality of Services with respect to resource constraints so that they could support reliable services and utilize available resources optimally. In this paper we present a new analytical and generic resource management model that is QoS-based. The approach for resource allocation and relevant algorithms is based on a mathematically proved model that manages resource and QoS allocation intelligently so that the total system utility of is maximized. We use the constructs of application benefit functions and resource demand functions to represent the system configuration and to solve the resource allocation problems. Extensive surveys on the related work including systematic and analytical approaches are also presented.     

Presto—A System Environment for Mission-Critical Multimedia Applications

Summarized in this report is a multiphased R and D program, presto, conducted for developing a multimedia system environment to support a variety of mission-critical applications. The concepts, software design, and system prototype developed during the first phase of the program are presented. In particular, the work on real-time scheduling, multimedia storage and retrieval, and application programming model is described. The major results of the presto Phase I program are a set of new techniques and system software for QoS- and criticality-based, adaptive multiresource management, raw-I/O-based continuous multimedia file management, and data flow-oriented programming with integrated real-time scheduling support.     

多媒体传感器网络视频的帧分类联合重构

为降低多媒体传感器网络中视频压缩感知的计算复杂度,提出一种基于帧分类的多媒体传感器网络视频联合重构算法。依据视频数据的联合稀疏模型将视频帧分为关键帧和非关键帧。对于压缩感知重构中欠定线性方程组,可利用关键帧和非关键帧之间的相关边信息进行重构初始化,同时运用有界约束二次规划对其进行求解。从仿真结果可知,相对于传统的视频压缩感知算法而言,在保证视频重构质量的前提下,所提方法在重构算法复杂度上不但能有效降低,同时,在视频重构上能提高其实时性。     

立体视频分级网络传输码率平滑方法

立体视频视角分级后会造成各视角码流的码率波动过大的现象,对网络传输及终端造成冲击.为解决该问题,提出一种自适应双缓冲码率平滑策略实现视角分级后的码率平滑.该方法根据视角分离后码率抖动的特点,在发送端对各视角码流进行两级缓冲码率平滑.不同视角的码流经过视角分离后存入各自缓冲区中并按帧率向第2级发送码流进行第1级平滑,经过...     

无线多媒体传感器网络视频流多路径路由算法

无线多媒体传感器网络中的视频流传输,需要提供多样QoS保障.提出一种基于改进蚁群算法多路径路由算法ACMRA(ant colony based multipath routing algorithm),以寻找具有多种优先级路径的路径集,并对重要性不同的视频数据进行相应路径的选择.通过优化网络链路上人工信息素的初始分布,改进后的蚁群算法具有更快的可行路径发现速度及收敛速度.多路径机制的引入提高了网络数据吞吐量与视频传输性能,同时可均衡网络资源,延长网络生命.实验结果表明,算法ACMRA在网络性能、视频传榆性能与网络生命周期方面,较之其他路由算法具有明显优势.     

Real-Time Disk Scheduling for Multimedia Applications with Deadline-Modification-Scan Scheme

Real-timedisk scheduling (RTDS) is important for time-critical multimediaapplications. In conventional approaches of real-time disk scheduling,such as SCAN-EDF, the seek-optimizing SCAN scheme is appliedto reduce the disk service time of the real-time EDF schedule.Since only tasks with the same deadline are seek-optimized, theobtained improvement of SCAN-EDF is limited. In this paper, basedon the maximum-scannable-group (MSG) concept, a deadline-modification-scan (DMS or DM-SCAN) algorithm is proposed.Our algorithm uses MSG to automatically decide the suitable taskgroups for seek-optimizing. Based on the MSG concept, we repeatedlyapply DMS to further increase disk throughput to support moretasks. We have implemented the proposed algorithm on UnixWare2.01. The appropriate problem behaviors and parameter valuesto yield good solutions are investigated. Experiments show thatDMS is better than conventional approaches in both the obtaineddisk throughput and the supported tasks. Moreover, our proposedapproach can schedule task sets that are not schedulable by EDFand SCAN-EDF.     

无线多媒体传感器网络中基于多类传感器信息的分布式视频处理

无线多媒体传感器网络中的多媒体传感器节点的功率、计算和存储能力及带宽资源受限,迫切需要低复杂度的视频处理技术对大数据量的视频进行压缩传输。基于来自网络中监控同一目标场景的多种类型传感器的信息,给出了一个新的无线多媒体传感器网络分布式视频处理系统框架;提出了一种基于多类型传感数据融合和多视角的GOP（group of picture）划分方法;在解码端,考虑单一视角视频序列之间较强的时间相关性,产生时间相关的边信息;利用来自多个视频传感节点的视频序列间的空间多视角相关性,产生多视角相关的边信息,并提供两种边信息的融合和选择机制,提高边信息的准确度和可靠性。最后仿真实验结果表明该方法的有效性和优越性。     

基于多媒体的过程化演示教学法在C语言教学中的应用

介绍了过程化演示教学方法及其在C语言教学中的应用。该教学方法以灵活应用知识为目的,首先设计问题,给出问题求解算法的伪代码和知识点应用的要求。借助于多媒体对求解算法进行逐步编程、分步演示、逐步细化、采用单步运行,进行测试和调试,对基础理论的正确性和应用方法进行过程化的演示和验证。通过由浅入深的分析讲解,使学生加深对基础知识的理解,掌握其应用方法和编程技巧,加强思维能力和应用知识能力的培养。     

基于服务质量需求的存储系统动态优先权调度策略

多媒体应用要求存储系统提供保证服务质量的数据访问服务,响应时间超过延迟上限的访问请求必须小于一定的比例.基于服务质量需求的动态优先权调度策略(QADPS)根据多媒体应用接受存储系统服务的历史信息,计算多媒体应用的服务质量失败距离;并为失败距离较小的多媒体应用分配较高的调度优先权.QADPS根据多媒体应用的不同服务质量需求,实现了有差别的调度：多媒体应用的服务质量需求越严格,它的访问请求被调度的机会越高. QADPS能够在保证服务质量的前提下,支持更多的并发多媒体应用.     

面向矿山监管的无人机视频关键帧影像动态提取方法

为满足对露天煤矿违法开采实时监测需求,提出了一种基于无人机瞬时航飞速度的视频关键帧影像动态提取方法。首先对无人机采集的视频影像进行预处理,提取视频影像中无人机瞬时飞行速度、飞行航高等信息;然后基于提取的相关信息加权化处理并结合相机参数进行计算,得出抽取关键帧所需的动态间隔,再对关键帧时间间隔进行加权和阈值约束处理,提取出关键帧的动态时差。实例验证表明,采用该方法提取的关键帧影像进行矿区三维重建,在保证三维场景的同时有效提高了数据处理速度,且比等时差法用时缩短了近5倍,显著提高了三维重建的效率。     

一种基于动态区间减少移动检测延时的方法

在移动IP中,根据子网前缀以及均匀分布于区间[min,max]上的广告间隙,移动节点检测它自身是否移动.因此,区间的长度对于移动检测延时有直接的影响.然而,在移动IP中,区间的静态配置既不方便也不灵活.根据链路带宽的利用率,提出了一种动态调整区间的新方法,并且进行了理论分析.结果显示,与静态区间相比,动态区间的方法显著地减少了不必要的移动检测延时.