Mathematical Analysis of caching policies and cooperation in YouTube-like services

Currently, most video on-demand services offered over the Internet do not exploit the idle resources available from end-users. We discuss the benefits of user-assistance in video on-demand systems, where users are both clients and servers, helping with the task of video distribution. The mathematical machinery for the systematic analysis of video on-demand services is not mature yet. In this paper we develop a deterministic fluid model to determine the expected evolution of user-assisted on-demand video streaming services. We theoretically prove that cooperative systems always outperform non-cooperative solutions. A combinatorial optimization problem is proposed, where the goal is to distribute a set of video items into repositories trying to offer the minimum waiting times to end-users. This combinatorial problem is proved to be in the class of NP-Complete computational problem, and is heuristically solved with a GRASP methodology. Predictions inspired in YouTube scenarios suggest the introduction of cooperation is both robust and extremely attractive from an economical viewpoint as well.     

MDVQM: A novel multidimensional no-reference video quality metric for video transcoding

In this paper, we study the impact of quantization, frame dropping and spatial down-sampling on the perceived quality of compressed video streams. Based on the analysis of quality ratings obtained from extensive subjective tests, we propose a no-reference metric (named MDVQM) for video quality estimation in the presence of both spatial and temporal quality impairments. The proposed metric is based on the per-pixel bitrate of the encoded stream and selected spatial and temporal activity measures extracted from the video content. All the values required to compute the proposed video quality metric can be obtained without using the original reference video which makes the metric for instance useful for making transcoding decisions in a wireless video transmission scenario. Different from comparable metrics in the literature, we have also considered the case when both frame rate and frame size are changed simultaneously. The validation results show that the proposed metric provides more accurate estimation of the video quality than the state of the art metrics.     

Does genre type influence choice of video platform? A study of college student use of internet and television for specific video genres

With the introduction of multichannel video programming distributors and different types of video platforms, consumers have more choices of channels and platforms than ever. Specifically, the present study focuses on television and the Internet as video platforms.     

A hierarchical design methodology for full-search block matching motion estimation

Many useful DSP algorithms have high dimensions and complex logic. Consequently, an efficient implementation of these algorithms on parallel processor arrays must involve a structured design methodology. Full-search block-matching motion estimation is one of those algorithms that can be developed using parallel processor arrays. In this paper, we present a hierarchical design methodology for the full-search block matching motion estimation. Our proposed methodology reduces the complexity of the algorithm into simpler steps and then explores the different possible design options at each step. Input data timing restrictions are taken into consideration as well as buffering requirements. A designer is able to modify system performance by selecting some of the algorithm variables for pipelining or broadcasting. Our proposed design strategy also allows the designer to study time and hardware complexities of computations at each level of the hierarchy. The resultant architecture allows easy modifications to the organization of data buffers and processing elements-their number, datapath pipelining, and complexity-to produce a system whose performance matches the video data sample rate requirements.     

一种串联蓄电池组电压巡检仪的设计

在线监测是目前工业中常见的监测方式,工业级应急电源的蓄电池便是需要监测的对象。用一种以单片机技术为核心,利用V/F转换的方法对单体蓄电池电压进行实时监测,采用光电隔离与变压器隔离的方法解决采集电路和单片机处理电路电气隔离的问题。给出巡检仪硬件结构框架,通过3种通信方式实现数据通信,并给出采集电路的供电方法。     

3G"新"彩铃引领3G新体验

3G彩铃在2G彩铃的基础上进一步演化，具备了个性化铃声和影像。用户可以自己设定动画、视频等内容。通过介绍3G彩铃的业务平台结构，描述业务平台的核心部分一业务服务器的功能。介绍了3G彩铃实现的原理基础，最后对3G彩铃业务的发展方向进行了阐述。     

短波测向软件的设计与实现

随着当今世界无线电技术和业务的快速发展以及社会需求的日益增长,空中电磁环境日趋复杂,各种无线电干扰时有发生,无线电监测的任务日趋繁重。介绍了一套短波监测系统中测向功能的设计与实现,其中介绍了无线测向的基本原理,详细分析了软件和测向设备EBD061之间的CORBA通信模式以及测向程序的基本流程和具体实现。     

一种基于最佳比特分配策略的三维小波视频编码新方法

对基于三维小波变换的视频编码进行了研究。由于视频图像传统的三维小波变换结构存在着诸多不足．文章提出了一种改进的三维小波变换结构。在给定的比特率条件下，通过对使得解码图像量化误差达到最小的最佳比特分配策略进行研究，给出了在均匀量化情况下的改进三维小波变换结构的量化步长。实验结果表明该方法的压缩性能明显优于传统方法。     

基于频域活动性的码率控制算法的研究

码率控制是恒定码率视频压缩编码系统的一个关键研究课题。本文提出了一种基于频域活动性的修正的TM5码率控制算法。该算法以TM5为基础，同时采用了一些有效的措施．诸如：频域括动性分析、场景变化分析、码字利用映像和强制缓存控制等。对所提出的修正的TM5码率控制算法．本文进行了计算机模拟实验，实验结果证明了本文所提出的算法可以有效地弥补现有的码率控制算法的不足，可适用于多种视频压缩的应用领域。     

单片视频D／A转换器SDA1016的电路分析与设计

对单片视频Ｄ／Ａ转换器ＳＤＡ１０１６进行了电路原理分析和优化设计，该结果可作为电路研制及应用的参考。给出了ＳＤＡ１０１６视频ＤＡＣ的复合视频应用电路。采用了某些模拟技术，实现了ＳＤＡ１０１６全直流分析、子电路（块）的瞬态分析，是ＳＰＩＣＥ用于ＬＳＩ电路分析和优化设计的成功例证。