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.     

视觉场景描述及其效果评价

作为计算机视觉、多媒体、人工智能和自然语言处理等领域的交叉性研究课题,视觉场景描述的研究内容是自动生成一个或多个语句用于描述图像或视频中呈现的视觉场景信息.视觉场景中内容的丰富性和自然语言表达的多样性使得视觉场景描述成为一项充满挑战的任务,综述了现有视觉场景描述方法及其效果评价.首先,论述了视觉场景描述的定义、研究任务及方法分类,简要分析了视觉场景描述与多模态检索、跨模态学习、场景分类、视觉关系检测等相关技术的关系;然后分类讨论视觉场景描述的主要方法、模型及研究进展,归纳日渐增多的基准数据集;接下来,梳理客观评价视觉场景描述效果的主要指标和视觉场景描述技术面临的问题与挑战,最后讨论未来的应用前景.     

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.     

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.     

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。     

An Object Flow Computer for Database Applications: Design and Performance Evaluation

In the past two decades, a considerable amount of research exists which uses hardware, firmware, and novel architectures to achieve the needed efficiency in implementing database management functions. However, most of the past efforts have been directed toward developing database computers for supporting a relatively primitive data model, namely, the relational model. This paper presents the design and evaluation of an Object Flow Computer (OFC). OFC is designed to efficiently support the processing of object-oriented databases. OFC employs a vertically fragmented data storage structure and a two-phase parallel query processing strategy. A set of primitive operators is defined for OFC. Depending on the performance requirement, these operators can be implemented in software running on general-purpose processors or as functions in special-purpose coprocessors. A high-level database request can be decomposed into these primitive operators and executed in parallel. OFC combines a number of known database processing techniques such as query decomposition, pipelining mode of data processing, and data flow control strategy. The performance evaluation of the proposed two-phase query processing strategy and a comparison with the conventional query processing strategy are also presented.     

机会网络中的自适应喷雾路由及其性能评估

针对传统喷雾路由无法适应动态网络环境的问题,提出了一类自适应喷雾路由机制.由具备最新网络知识的中间转发节点实时地进行喷雾决策,达到对网络环境的快速感知和适应,并在特定的喷雾方式下,以最低的路由代价满足目标时延约束.对提出的3种不同的喷雾机制从路由代价、副本冗余度以及期望延迟3个方面给出了理论上的分析.仿真评估结果表明,自适应喷雾路由具备路由代价低、自适应能力强、扩展性佳等特点,所提出的喷雾机制各有特点和应用场景,是一类正确有效的时延约束机会路由协议.     

基于AFDX自适应优先调度算法的实时性分析

通过分析AFDX终端系统关键技术,在AFDX网络虚拟链路的调度策略中提出采用自适应优先调度算法;并分析数据包在终端系统中的处理过程,进行网络演算建模,进而确定出AFDX网络针对不同类型数据的传输速率和服务时延.结果证明该算法较好地满足了航空电子网络数据传输实时性需求,并为AFDX智能网络管理模型中的参数模型和调度策略提...     

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。     

TinyOS路由协议原理及性能评估

LEPS是TinyOS的多跳路由协议,适用于数据聚集型传感器网络。LEPS路由建立一个以汇聚节点为根节点的树型拓扑,每个节点向自己的父节点发送传感数据,并沿最短路径传送到汇聚节点。LEPS协议将跳数和链路质量作为选择父节点的依据,具有一定的传输可靠性保证。该文对LEPS的原理以及在TinyOS中的实现机制进行了分析,在实际的传感器网络中进行了性能实验。LEPS路由协议可以形成并维护一个树型拓扑,但是节点间链路不够稳定,拓扑变化比较频繁。     

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.     

IEEE 802.15.4 MAC 的分析与性能评估

本文针对无线传感网络中如何提高网络的传输性能的问题,提出了对不同的网络拓扑结构采用不同的传输方式。在分析了网络中两种不同的网络结构:"树形"结构及"网形"结构的基础上,运用NS2网络仿真软件,重点分析了在信标使能和非信标使能两种不同的传输方式下,通过改变发包速率来仿真两种不同网络结构中的分组投递率(丢包率)、平均端到端延时和路由开销等网络性能参数。实验结果表明,对不同的网络拓扑结构,有针对性地采用不同的传输方式确实可以提高其传输性能。     

SL-SOAP：一个大型分层视频组播代理自组织协议

针对大型分层视频组播层次化自适应体系HALVM中层次化代理的位置和功能如何动态配置和管理的核心问题,本文在研究和分析了层次化代理的逻辑构成和视频组播原始拓扑结构特点的基础上,利用共享丢失模型,提出了一个代理动态自组织协议SL-SOAP。该协议首次将多视频组播会话自组织代理从逻辑上分成多个进程,提出了多个视频组播会话自组织代理中多个进程的优化定位方法,并通过应用证实了该协议的有效性。     

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.     

视频挖掘：概念、技术与应用*

视频挖掘旨在提取视频数据的语义信息并挖掘出隐含其中的有用模式和知识,从而有助于提高视频的智能应用水平,通过资料分析和文献查证,详细总结并探讨了视频挖掘的概念、技术实现方法和应用领域,并指出了视频挖掘的研究挑战。     

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。