基于CDMA1x的H.264无线远程视频监控押运系统

在分析当前无线远程视频监控系统的发展趋势的基础上,给出了一种基于CDMA1x无线网络,采用DSP实现H.264编码协议的无线远程视频传输系统的设计方案.结合嵌入式Linux构成一个数据采集编码处理终端,将采集到的图像数据按照H.264标准进行编码,得到的码流可以通过CDMA1x无线信道传输.接收端的解码显示图像格式为CIF或QOF视频,采用帧频的方式显示,在有限的带宽内满足应用需求.     

基于CDMA1x的H．264无线远程视频监控押运系统

在分析当前无线远程视频监控系统的发展趋势的基础上,给出了一种基于CDMA1x无线网络,采用DSP实现H.264编码协议的无线远程视频传输系统的设计方案。结合嵌入式Linux构成一个数据采集编码处理终端,将采集到的图像数据按照H.264标准进行编码,得到的码流可以通过CDMA1x无线信道传输。接收端的解码显示图像格式为CIF或QCIF视频,采用帧频的方式显示,在有限的带宽内满足应用需求。     

基于AVS协议的无线图像采集系统设计

无线图像采集系统的信源标准发展较快,我国自主知识产权的二代标准AVS目前优势突出,基于这一协议的无线图像采集系统设计主要包括图像硬件采集系统、图像信息的采集数字化、视频采集技术和视频压缩等,可通过高编码效率的AVS标准的应用来一体化的提升无线图像采集系统的工作效率。     

基于Hi3516的监控视频自适应ROI编码

介绍了基于感兴趣区域（ROI）的智能视频监控编码传输基本原理,以及基于单芯片SoC Hi3516的自适应ROI编码软硬件实现方案。在对Hi3516硬件特性进行介绍同时,也给出了利用运动侦测功能和其他手段对ROI进行自动检测,以及利用硬件编码通道进行基于H.264的ROI编码和传输方法。实验结果表明,该系统能实时检测视频中的运动目标并进行ROI编码,使得系统在低码率下也能获得很好的图像重建效果。     

基于智能图像分析的视频质量诊断系统关键技术研究

随着视频监控系统的应用范围不断扩大,监控摄像头数目在不断增加,如何有效地检测维护监控系统就变得非常重要。基于智能图像分析技术的视频质量自动诊断系统应运而生,该系统可在视频图像发生信号丢失、视频遮挡、亮度异常、清晰度异常、画面冻结、偏色、雪花干扰等异常情况下,及时发现并报警,大大增加了视频监控系统的可靠性,提高了安防效率。文章将对视频质量诊断系统中常见的各类图像异常情况的检测算法及检测流程加以讨论。     

基于ARM的视频监控系统

设计了一种基于三星ARM9的S3C2440芯片的视频监控系统.该系统通过摄像头采集图像并对图像进行运动检测和压缩编码.实验结果表明该系统保持了图像传输的流畅性,同时能够时运动的入侵目标进行闪烁标注,达到入侵、运动检测的目的.     

基于记忆单元与多尺度结构相似性的异常检测

针对基于记忆单元的自编码器模型(Dynamic Prototype Unit Model,DPU)在检测视频异常时没有充分利用多层次特征、未考虑异常与正常事件间的结构性差异的问题,提出融合多尺度记忆模块和多尺度结构相似性的异常检测模型.新模型构建了多尺度记忆模块(Multi Scale Memory Module),利用不同尺度空间的记忆单元对编码层特征进行编码,并将编码结果与解码层特征拼接,既能保留网络的浅层细节信息,又能促进正常模式的多样性.为了约束对正常事件中结构信息的学习,组合多尺度结构相似性(Multi Scale Structure Similarity Index,MS-SSIM)误差与L 1误差作为目标函数,使预测视频中的事件结构更接近正常事件,提高视频中异常事件的预测误差.在标准数据集UCSD Ped1、UCSD Ped2和Avenue数据集上的实验结果表明,提出模型的帧级AUC比原模型分别提高了0.8%、3.4%和1.0%,帧率达到142.9 fps.     

一种基于光流法的逆行异常事件检测方法

机场大厅、公路等公共场合,经常需要行人或车辆单向运动,以保障开放环境的安全性及秩序性.对监控视频中的逆行异常事件进行检测,便于管理人员及时对可疑事件做出处理.提出了一种逆行异常事件的检测算法,它基于图像中特征点的光流场以及空间分布特性对特征点进行聚类,然后通过计算符合逆行条件的特征点数量实现对逆行异常事件的检测.理论分...     

基于CDMA／GPRS的电力杆线视频监控的设计

为适应电力系统自动化建设和管理的需要，针对当前电力线路巡线管理中存在的问题，提出了应用无线公用传输网络，把经过数字化压缩、编码的视频和告警数据传送至监控中心，中心的计算机对各种数据进行解压缩、解编码同时回放视频图像，对报警事件进行告警处理，构成电力线路监控系统计算机化管理的新方案。     

基于ADI DSP-BF533的H.264视频采集编码系统设计

设计了一种嵌入式H.264视频流采集编码传输系统.方案基于ADI公司的视频处理器ADSP-BF533,通过摄像头采集视频图像并存储,在DSP内采用软编码的方式对采集的视频图像进行H.264压缩处理.通过以太网接口实现压缩的数据流传输以太网传输.     

An Experimental Delay Analysis Based on M/G/1-Vacation Queues for Local Audio/Video Streams

The delay which is one of the quality of service parameters is considered to be a crucial factor for the effective usage of real-time audio and video streams in interactive multimedia collaborations. Among the various causes of the delay, we focus in this paper on the local delay concerned with the schemes which handle continuous inflow of encoded data from constant or variable bit-rate audio and video encoders. We introduce two kinds of implementation approaches, pull model and push model. While the pull model periodically pumps out the incoming data from the system buffer, the push model receives events from the device drivers. From our experiments based on Windows NT 3.51, it is shown that the push model outperforms the other for both constant and variable bit-rate streams in terms of the local delay, when the system suffers reasonable loads. We interpret this experimental data with M/G/1 multiple vacation queuing theories, and show that it is consistent with the queuing theoretic interpretations.     

Bit-Rate Efficiency of H.264 Encoders Measured With Subjective Assessment Techniques

In this study we evaluated the bit-rate efficiency of current hardware H.264 encoders as compared to that of established MPEG-2 hardware encoders. To estimate bit-rate efficiency, we measured the subjective video quality of MPEG-2 encoded material processed at three bit rates: 8, 12, and 16 Mbps, and determined the bit-rate at which H.264 encoded material produced similar subjective video quality. The MPEG-2 and H.264 bit rates that resulted in the same perceived video quality were used to estimate bit-rate efficiency.      

Multiuser cross-layer resource allocation for video transmission over wireless networks

With the advancement of video-compression technology and the wide deployment of wireless networks, there is an increasing demand for wireless video communication services, and many design challenges remain to be overcome. In this article, we discuss how to dynamically allocate resources according to the changing environments and requirements, so as to improve the overall system performance and ensure individual quality of service (QoS). Specifically, we consider two aspects with regard to design issues: cross-layer design, which jointly optimizes resource utilization from the physical layer to the application layer, and multiuser diversity, which explores source and channel heterogeneity for different users. We study how to efficiently transmit multiple video streams, encoded by current and future video codecs, over resource-limited wireless networks such as 3G/4G cellular system and future wireless local/metropolitan area networks (WLANs/WMANs).     

Bit-rate control algorithm on video packet coding and its characteristics

A bit-rate control method based on a hybrid coding algorithm is proposed for packet video coding. Three types of bit-rate control modes, the constant bit-rate mode, the average bit-rate control mode and the free bit-rate mode, are investigated. According to the opinion test the latter two modes have an advantage in video quality over the constant bit-rate mode. A teleconference terminal, which includes this video codec, audio codec and packet adaptor, is implemented in actual hardware on High-speed Packet Switching system. On this system, video information are transmitted in UI frame (a packet format in X.25 protocol) at 64 K 800 Kbit/s.     

低速率的无线视频监控系统设计与实现

随着低速率的视频编码技术与无线通信技术的迅速发展,使得为用户提供移动视频监控业务成为可能。这里,文章实现了一套在移动环境下的实时视频监控系统。该系统融合了H.264视频编码技术,并对H.264核心代码进行了优化,以确保其在处理能力较弱的移动终端上流畅解码。实验表明,即使在低速率的无线网络环境下,也可以获得较高质量的监控图像。     

Optimal quality adaptation for scalable encoded video

The dynamic behavior of the Internet's transmission resources makes it difficult to provide perceptually good quality streaming video. Scalable video encoding techniques have been proposed to deal with this problem. However, an encoded video generally exhibits significant data rate variability to provide consistent visual quality. We are, therefore, faced with the problem of accommodating the mismatch between the available bandwidth variability and the encoded video variability. We investigate quality adaptation algorithms for scalable encoded variable bit-rate video over the Internet. Our goal is to develop a quality adaptation scheme that maximizes perceptual video quality by minimizing quality variation, while at the same time increasing the usage of available bandwidth. We propose an optimal adaptation algorithm and a real-time adaptation algorithm based on whether the network conditions are known a priori. Experimental results show that the real-time adaptation as well as the optimal adaptation algorithm provide consistent video quality when used over both TCP-friendly rate control (TFRC) and transmission control protocol (TCP).     

Perceptually adaptive joint deringing–deblocking filtering for scalable video transmission over wireless networks

Video transmission over low bit-rate channels, such as wireless networks, requires dedicated filtering during decoding for crucial enhancement of the perceptual video quality. For that reason, deringing and deblocking are inevitable components of decoders in wireless video transmission systems. Aimed at improving the visual quality of decoded video, in this paper a new perceptually adaptive joint deringing–deblocking filtering technique for scalable video streams is introduced. The proposed approach is designed to deal with artefacts inherent to transmissions over very low bit-rate channels, specifically wireless networks. It considers both prediction and update steps in motion compensated temporal filtering in an in-loop filtering architecture. The proposed approach integrates three different filtering modules to deal with low-pass, high-pass and after-update frames, respectively. The filter strength is adaptively tuned according to the number of discarded bit-planes, which in turn depends on the channel bit-rate and the channel error conditions. Furthermore, since ringing and blocking artefacts are visually annoying, relevant characteristics of the human visual system are considered in the used bilateral filtering model. That is, the amount of filtering is adjusted to the perceptual distortion by integrating a human visual system model into filtering based on luminance, activity and temporal masking. As a consequence, the resulting filter strength is automatically adapted to both perceptual sensitivity and channel variation. To assess the performance of the proposed approach, a comprehensive comparative evaluation against the conventional loop architecture and bilateral filter was conducted. The results of the experimental evaluation show a superior performance of the proposed adaptive filtering approach, providing better objective and subjective quality.     

Improved Compression Performance of H.264/MPEG4-AVC for Digital Video Using DVDP

Digital video sequences in uncompressed form require huge storage and high transmission bandwidth for multimedia communication. The increasing number of Video over Wireless (VoW) services is creating greater thrust for higher coding efficiency for digital video signals. Efficient coding and transmission control techniques are required to meet the needs of Quality of Service (QoS). H.264/MPEG4-advanced video coding (AVC) video enCOder/DECoder (CODEC) is the latest coding and compression standard from the International Telecommunications Union-Telecommunication (ITU-T). This standard is currently dominating the field by offering a flexible architecture and compression gain for video coding. Due to its high compression efficiency with low compression delay, it is used in many real time VoW transmission applications. Modern wireless networks provide many different means to adapt QoS like low end-to-end delay, efficient bandwidth-utilization and lower bit-rate. This paper presents a design of integrated CODEC scheme with relatively lower bit-rate and improved edge peak signal-to-noise ratio (EPSNR). Several important factors of video sequence are analyzed for achieving lower bit-rate. A new scheme is proposed at Application (APP) layer for video compression, called as Enhanced Intra Prediction (EnIP). This algorithm uses picture structure without B-pictures for real time VoW application. The proposed algorithm is implemented on TMS320DM6437; a multimedia processor, using Digital Video Development Platform (DVDP). The superior performance of the proposed EnIP algorithm is validated by experimental results. It shows that the implementation of EnIP using digital multimedia processor lowers the bit-rate and improves EPSNR significantly.     

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。     

A bit allocation scheme for a class of embedded wavelet video encoders

In this paper, we investigate bit allocation strategies for a class of embedded wavelet video encoders. They take advantage of the precise control that such coders have over the bit-rate of each frame. We first show that a piecewise-linear model suits the rate × distortion characteristics of these encoders better than an exponential model, specially in low bit-rate applications. Then, we use an effective iterative procedure for dealing with the problem of frame dependency which yields improved rate × distortion results. Two types of embedded wavelet coders, using scalar and vector quantization, are tested. The results are encouraging, showing that the adoption of an adequate rate-control strategy can improve both objective and subjective quality of video sequences encoded using such embedded wavelet video encoders.