Smooth Control of Adaptive Media Playout for Video Streaming

Client-side data buffering is a common technique to deal with media playout interruptions of streaming video caused by network jitters and packet losses of best-effort networks. However, stronger playout interruption protection inevitably amounts to larger data buffering and results in more memory requirements and longer playout delay. Adaptive media playout (AMP), also a client-side technique, can reduce the buffer requirement and avoid buffer outage but at the expense of visual quality degradation because of the fluctuation of playout speed. In this paper, we propose a novel AMP scheme to keep the video playout as smooth as possible while adapting to the channel condition. The triggering of the playout control is based on buffer variation rather than buffer fullness. Experimental results show that our AMP scheme surpasses conventional schemes in unfriendly network conditions. Unlike previous schemes that are tuned for a specific range of packet loss and network instability, the proposed AMP scheme maintains consistent performance across a wide range of network conditions.     

Framework for Performance Evaluation of Face, Text, and Vehicle Detection and Tracking in Video: Data, Metrics, and Protocol

Common benchmark data sets, standardized performance metrics, and baseline algorithms have demonstrated considerable impact on research and development in a variety of application domains. These resources provide both consumers and developers of technology with a common framework to objectively compare the performance of different algorithms and algorithmic improvements. In this paper, we present such a framework for evaluating object detection and tracking in video: specifically for face, text, and vehicle objects. This framework includes the source video data, ground-truth annotations (along with guidelines for annotation), performance metrics, evaluation protocols, and tools including scoring software and baseline algorithms. For each detection and tracking task and supported domain, we developed a 50-clip training set and a 50-clip test set. Each data clip is approximately 2.5 minutes long and has been completely spatially/temporally annotated at the I-frame level. Each task/domain, therefore, has an associated annotated corpus of approximately 450,000 frames. The scope of such annotation is unprecedented and was designed to begin to support the necessary quantities of data for robust machine learning approaches, as well as a statistically significant comparison of the performance of algorithms. The goal of this work was to systematically address the challenges of object detection and tracking through a common evaluation framework that permits a meaningful objective comparison of techniques, provides the research community with sufficient data for the exploration of automatic modeling techniques, encourages the incorporation of objective evaluation into the development process, and contributes useful lasting resources of a scale and magnitude that will prove to be extremely useful to the computer vision research community for years to come.     

智能视频算法评估综述

智能视频监控在公共安全和民用领域已经显现出有效与广阔的应用前景,备受国内外学者和众多实际工程领域专家的高度关注,制定有效、公正的智能视频算法评估准则是其应用过程中的一个重要环节.文中对当前国际上智能视频算法的评估工作进行了比较全面的综述,重点是运动检测、目标跟踪的性能评估.最后指出了智能视频算法评估的发展方向.     

网络应用程序中定时器的设计与性能评估

提出了一种理想定时器模型,并根据此模型提出了多个评价定时器性能的指标。对一个实际业务支撑系统的相关数据分析表明：业务请求消息的处理规模和相应的往返时间之间具有显著的线性相关性,基于此规律,该文给出了一种适用于具有任意处理规模的业务请求消息的定时器设计方法,并通过仿真分析了定时器在上述评价指标下的性能。     

从视频到语言:视频标题生成与描述研究综述

视频标题生成与描述是使用自然语言对视频进行总结与重新表达.由于视频与语言之间存在异构特性,其数据处理过程较为复杂.本文主要对基于“编码?解码”架构的模型做了详细阐述,以视频特征编码与使用方式为依据,将其分为基于视觉特征均值/最大值的方法、基于视频序列记忆建模的方法、基于三维卷积特征的方法及混合方法,并对各类模型进行了归纳与总结.最后,对当前存在的问题及可能趋势进行了总结与展望,指出需要生成融合情感、逻辑等信息的结构化语段,并在模型优化、数据集构建、评价指标等方面进行更为深入的研究.     

从视频到语言:视频标题生成与描述研究综述

视频标题生成与描述是使用自然语言对视频进行总结与重新表达.由于视频与语言之间存在异构特性,其数据处理过程较为复杂.本文主要对基于“编码?解码”架构的模型做了详细阐述,以视频特征编码与使用方式为依据,将其分为基于视觉特征均值/最大值的方法、基于视频序列记忆建模的方法、基于三维卷积特征的方法及混合方法,并对各类模型进行了归纳与总结.最后,对当前存在的问题及可能趋势进行了总结与展望,指出需要生成融合情感、逻辑等信息的结构化语段,并在模型优化、数据集构建、评价指标等方面进行更为深入的研究.     

无线传感器网络的控制协议及协议覆盖性能评价研究

在无线通信、传感技术及嵌入式技术不断发展的过程中逐渐形成了无线传感器网络,覆盖策略是无线传感器网络中最基本的问题,也是最需要解决的问题,其能够保证无线传感器节点部署实现被检测目标和区域的覆盖。在无线传感器网络不断发展的过程中,覆盖传输控制出现了多种问题。基于此,就对无线传感器网络控制问题进行分析,总结了目前传输控制协议和设计的思想,提出了全新的无线传感器网络覆盖控制协议,最后对协议的性能进行研究,证明其具有良好的覆盖率,能够实现快速收敛。     

Architecture and Performance Evaluation for Redundant Multicast Transmission Supporting Adaptive QoS

In this paper we describe the architecture of an application that was developed for the transmission of multimedia data, using the multicast mechanism, over the Internet. There are two major issues that have to be considered when designing and implementing such a service, the fairness and the adaptation schemes. The fairness problem results from the fact that Clients with different capabilities have to be served. In our application we use a mechanism that categorizes the Clients into a number of groups according to each Client's capabilities and (the mechanism) serves each group of Clients with a different multicast stream. With the term capabilities we do not only mean the processing power of the Client, but also the capacity and the condition of the network path towards that Client. Because of today's Internet heterogeneity and the lack of Quality of Service (QoS) support, the Server cannot assume that the Clients will permanently be able to handle a specific bit rate. We have therefore implemented an additional mechanism for the intra-stream bit rate adaptation. The proposed mechanism uses a friendly to the network users congestion control policy to control the transmission of the data. We evaluate the adaptive multicast transmission mechanism through a number of experiments and a number of simulations in order to examine its behaviour to a heterogeneous group of Clients and its behaviour against TCP and UDP data streams.     

SA-MAC: Self-Stabilizing Adaptive MAC Protocol for Wireless Sensor Networks

A common method of prolonging the lifetime of wireless sensor networks is to use low power duty cycling protocol. Existing protocols consist of two categories: sender-initiated and receiver-initiated. In this paper, we present SAMAC, a self-stabilizing adaptive MAC protocol for wireless sensor networks. SA-MAC dynamically adjusts the transmission time-slot, waking up time-slot, and packet detection pattern according to current network working condition, such as packet length and wake-up patterns of neighboring nodes. In the long run, every sensor node will find its own transmission phase so that the network will enter a stable stage when the network load and qualities are static. We conduct extensive experiments to evaluate the energy consumption, packet reception rate of SA-MAC in real sensor networking systems. Our results indicate that SA-MAC outperforms other existing protocols.     

无线Ad hoc网络下DSR协议的改进及性能评价

本文介绍了Adhoc网络及其DSR协议,针对它用全网洪泛方式进行路由发现而导致较大的网络负载问题,提出了一种自适应局部化搜索机制,并用NS-2实现了新机制。     

High Data Rate Video Transmission Using Parallel TCP Connections: Approaches and Performance Evaluation

In our study, we investigate a packet-level protocol parallelization approach, which works by parallel multithreading the protocol execution such that packets within and among connections are processed in parallel using distinct processors/threads. The major advantage of this approach is its high scalability—with proper scheduling, more protocol connections, and hence more requests, can be supported by using more threads. In this paper, we present results of our detailed simulations using the NS-2 platform for reliably transferring video stream data in a client-server system. Different types of parameters are used to measure the performance. The parameters include available network bandwidth, different number of TCP connections, and different video sources. Our results show that a parallel approach can indeed significantly enhance the playback quality.     

基于时延Petri网的密码协议分析及性能评估

形式化分析方法由于其精炼、简洁和无二义性逐步成为分析密码协议的一条可靠和准确的途径，但是密码协议的形式化分析研究目前还不够深入，针对这一现状，该文提出用时延Petri网来表示和分析密码协议。该模型不但能够反映协议的静态和动态的特性，而且能够对密码协议进行时间、空间上的性能评估。作为实例，文章对MSR无线协议作了详细的形式分析和性能评估。最后，与其它形式化分析密码协议的方法作了比较。     

EduMedia：教学数字视频图书馆中异构资源的统一描述

文中在分析了书目数据,普通文档数据和教学视频数据的特征,以及专用的元数据描述方法的基础上,提出了一种基于资源描述框架RDF的元数据描述方案EduMedia,从而实现了对于这三种异构资源的元数据的统一描述。     

HALVM:一个大型分层视频组播层次化自适应体系

针对端点自适应方法和基于静态配置代理的应用自适应方法无法满足大型视频组播扩展性、动态性和复杂性要求这一难点问题,提出了一个基于自组织代理的视频组播层次化自适应体系HALVM.该体系综合了代理的动态自组织协议和可伸缩性视频转换编码技术,将复杂的大型视频组播应用系统的动态自适应问题分解为层次化的小型视频组播应用子系统,由发送端、接收端和层次化代理分布完成自适应功能,是一个扩展性能好、管理与控制效率高的自适应解决方案.     

Performance Evaluation of a Parallel Pipeline Computational Model for Space-Time Adaptive Processing

This paper presents further results on the design and implementation of various optimizations based on our earlier work of developing a parallel pipelined model for the computational intensive applications that have multiple processing tasks. Performance evaluation of this model was done by using a real-time airborne radar application that employs a Space-Time Adaptive Processing (STAP) algorithm. This paper focuses on the following four issues: (1) The tradeoffs between increasing the throughput and reducing the latency are examined in more detail when allocating processors among different processing tasks. (2) A multi-threaded design is incorporated into the pipeline model and implemented on a massively parallel computer with symmetric multi-processor nodes, which shows enhanced performance. (3) The disk I/O is incorporated into the parallel pipeline to study its effect on performance in which two I/O task designs have been implemented: embedding I/O in the pipeline or having a separate I/O task. By using a double buffering approach together with the asynchronous I/O, the overall pipeline performance scales well as the number of processors increases. (4) From the comparison of the two I/O implementations, it is discovered that the latency may be improved when merging multiple tasks into a single task. The effect of reorganizing the task structure of the pipeline is discussed in detail. All the performance results shown in this work demonstrate the linear scalability the parallel pipeline model can achieve using a production radar application. Although this paper focuses on the implementation of the parallel pipeline model and uses the results from a STAP application to support the claims of the discovered properties for this pipeline, this model is also applicable to many other types of applications with similar computational characteristics.     

数字作品版权保护协议及其应用

设计了一个协议,利用数字水印和公共密码机制,可以确定作品的每一个拷贝的来源,从而达到阻止非法拷贝的目的,实现数字作品的版权保护。     

The ShareGrid Peer-to-Peer Desktop Grid: Infrastructure,Applications, and Performance Evaluation

Peer-to-Peer (P2P) Desktop Grids are computing infrastructures that aggregate a set of desktop-class machines in which all the participating entities have the same roles, responsibilities, and rights. In this paper, we present ShareGrid, a P2P Desktop Grid infrastructure based on the OurGrid middleware, that federates the resources provided by a set of small research laboratories to easily share and use their computing resources. We discuss the techniques and tools we employed to ensure scalability, efficiency, and usability, and describe the various applications used on it. We also demonstrate the ability of ShareGrid of providing good performance and scalability by reporting the results of experimental evaluations carried out by running various applications with different resource requirements. Our experience with ShareGrid indicates that P2P Desktop Grids can represent an effective answer to the computing needs of small research laboratories, as long as they provide both ease of management and use, and good scalability and performance.     

Formal Performance Modelling and Evaluation of an Adaptive Mechanism for Packetised Audio over the Internet

A case study is presented which concerns the design of an adaptive mechanism for packetised audio for use over the Internet. During the design process, the audio mechanism was modelled with the stochastically timed process algebra EMPA and analysed via simulation by the EMPA based software tool TwoTowers in order to predict the percentage of packets that are received in time for being played out. The predicted performance figures obtained from the algebraic model illustrated in advance the adequacy of the approach adopted in the design of the audio playout delay control mechanism. Based on these performance figures, it was possible to implement and develop the complete mechanism without incurring additional costs due to the late discovery of unexpected errors or inefficiency. Performance results obtained from experiments conducted on the field confirmed the predictive simulative results. Received March 1997 / Accepted in revised form July 1998