基于H.264算法的视频传输系统实现

本文介绍了基于H.264算法的视频传输系统的实现方案.该方案采用目前最新的视频压缩标准--H.264作为视频编解码算法,i.Mx27作为系统的中心处理器.嵌入式Linux作为操作系统,RTP/UDP作为网络传输协议,实现了视频实时的在网络上以流媒体格式的传输播放.系统运行结果表明:本课题研究的基于H.264视频编码算法的网络视频传输系统实现了可以实现高质量的视频信息传输效果(D1画质,屏幕分辨率为720*480,视频播放速率为30fps,最大码流为4Mbps).除此之外,为了保证视频信息在传输过程中安全性,该系统设计方案还采取了软硬件结合的加密方式处理视频信息.     

基于RTP的H.264视频流实时打包传输的研究

随着无线宽带网络的快速发展,以及高效的视频压缩技术的应用,流媒体的实时高效传输成为亟待解决的问题。本文从视频传输系统模型入手,分析了最新视频编码标准H.264在算法上的层次结构特点以及音、视频实时传送协议RTP的高效性。并且随着适合H.264流的RTP载荷格式的提出,基于RTP的H.264流媒体无线传输渐渐地得到应用。本文成功实现了一种基于RTP的H.264传输算法,实验通过了TD330无线3G模块测试,并且获得良好的图像质量,实现了低时延、较小丢包率的打包算法。     

达芬奇TMS320DM6446的视频软件设计

针对视频监控系统对实时性和带宽的高要求,提出以达芬奇异构双核处理器TMS320DM6446为基础的解决方案.双核间的通信和协作是基于编解码器引擎机制来实现的.ARM子系统负责I/O端口控制、算法调度、图形用户界面、网络传输等操作,DSP子系统则实现H.264视频编解码.经过研究,实现了视频软件设计.该方案实时性较好、部署方便,在视频监控领域具有较好的应用前景.     

基于JMF的电梯实时视频广播系统

为了实现建筑物的真正智能化和信息化,解决电梯作为建筑物内的"信息孤岛"这一问题,本文构建了一套基于JMF的网络视频实时广播系统.本文先概要叙述该系统的实现技术:MPEG-4编解码算法、RTP/RTCP实时传输协议,流媒体技术,然后利用Sun公司开发的专门应用于网络视频传输与播放的JMF包,针对电梯这一特殊环境构建网络视频广播系统.     

视频流媒体传输失真研究

由于网络传输引起的视频流媒体质量损失（称为传输失真）是流媒体QoS中最重要的参考指标，通常只能在终端系统解码后获得．本文根据视频流媒体编解码、错误隐藏、错误扩散等理论进行分析，提出了一个视频流媒体传输失真模型，谊模型可以在发送端通过网络传输质量和视频流媒体特性参数估算视频流媒体的最终表现质量，可以为流媒体同步、控制算法提供定量的参考指标．该模型针对常见的视频流媒体处理机制进行建模，并不局限于特定的编解码格式，具有更广泛的实用价值．     

基于TMDXEVM6446的网络视频监控系统

网络视频监控系统是集视频编解码和流媒体传输技术为一体的综合系统,提供了实时快捷的监控服务,近年来得到越来越广泛的应用。本文详细介绍了H.264/AVC视频编码新标准在TMDXEVM6446平台上的移植和优化,并完成了基于H.264编解码的网络视频监控系统完整的设计与实现。     

基于Intel XScale PXA255处理器的远程视频采集系统的设计与实现

本文介绍了一种基于嵌入式Linux和Intel Xscale PXA255处理器设计并实现的远程视频采集系统,它通过USB摄像头获取实时视频,使用Video4Linux提供的API函数进行视频采集程序的设计,采用先进的H．264算法压缩编码,通过实时流媒体传输技术实现了网络传输。     

基于解码矩阵的网络视频监控系统设计

针对当前网络视频监控系统具有的功能不能满足特殊现场需求的问题,设计了一种可以将监控画面直接在电视墙上显示、具有解码软矩阵的网络视频监控系统。系统包括网络视频预览模块和软矩阵解码模块,采用了H.264编解码算法对网络视频进行处理,RTP/RTCP流媒体传输协议进行传输。总体来说,本文所设计的网络视频监控系统,具有价格低、性能强、通用性好以及扩展能力强等优点。     

基于S3C2410与MPEG-4的播放器的设计和实现

流媒体(Streaming Media)是一种新兴的网络传榆技术,广泛应用在互联网上实时传输、播放音、视频等多媒体数据,流媒体技术包括流媒体数据的采集、音/视频编解码、存储、传输以及播放等领域.嵌入式流媒体,顾名思义,需要考虑嵌入式系统以及流媒体技术两方面的特点.本文介绍了一种基于S3C2410与MPEG-4的嵌入式流媒体播放器的软件和硬件的设计与实现.     

基于H.323的气象视频电视会商系统设计与实现

文章介绍了基于H.323的广西气象视频电视会商系统设计、功能和应用,通过利用当今先进的H.26动态视频编解码技术在SDH数字电路专网上实现“区-市-县”远程视频电视会商,系统建成后能够实现异地视频会商、会议及各种教学培训,在实际应用中发挥出明显的社会和经济效益。     

QoE management for video conferencing applications

We introduce a framework for managing the QoE of videos coded with the H.264 codec and transmitted by video conferencing applications through limited bandwidth networks. We focus our study on the medium-motion videos with QCIF, CIF, and VGA resolutions, the most pervasive video formats used by video conferencing applications across the Internet and cellular telephony systems. Using subjective tests for measuring the level of video quality perceived by end users, we expose the relation between the main influential video parameters and the quality experienced by end users. Furthermore, after investigating the effect of different frame rates and compression levels on video streaming bit rate, and consequently on QoE, we propose a QoE control mechanism for limited-bandwidth situations. A congestion control technique is also introduced in this paper and used in simulations for verifying the efficiency of the proposed QoE management algorithm and to implement this algorithm for practical applications.     

基于自动镜头分割的视频压缩编码算法

将镜头分割引入压缩编码,针对分割镜头特性确定适当的编码器及参数,能够提高视频压缩编码的效率．为此,提出了一种基于对分查找的镜头分割算法(VSSB)以及关键帧频率计算公式．其算法的核心是通过对分查找形成二叉树,同时通过广度优先搜索寻找分割点,具有O(log n)的时间复杂性．针对实时应用,采用了双阈值比较的镜头分割算法,能够较好地实现镜头切变和渐变的检测．基于镜头分割算法,建立并实现了并行方式的编解码系统模型．实验证明,基于镜头分割的编码方法能够提高压缩比,缩短压缩编码时间,有利于改善重建图像质量。     

MIJ2K Optimization using evolutionary multiobjective optimization algorithms

This paper deals with the multiobjective definition of video compression and its optimization. The optimization will be done using NSGA-II, a well-tested and highly accurate algorithm with a high convergence speed developed for solving multiobjective problems. Video compression is defined as a problem including two competing objectives. We try to find a set of optimal, so-called Pareto-optimal solutions, instead of a single optimal solution. The two competing objectives are quality and compression ratio maximization. The optimization will be achieved using a new patent pending codec, called MIJ2K, also outlined in this paper. Video will be compressed with the MIJ2K codec applied to some classical videos used for performance measurement, selected from the Xiph.org Foundation repository. The result of the optimization will be a set of near-optimal encoder parameters. We also present the convergence of NSGA-II with different encoder parameters and discuss the suitability of MOEAs as opposed to classical search-based techniques in this field.     

视频阵列处理器多层次分布式存储结构设计

随着视频编解码标准的不断演进,算法处理的数据量也随之剧增。多核结构并行化处理技术在提升算法计算速度的同时,使得存储结构成为了整个编解码系统性能的瓶颈。针对视频编解码算法访存的局部性、各算法之间数据交互频繁性、算法内部大量临时数据不交互性的特点,设计并实现了由私有存储层和共享存储层构成的多层次分布式存储结构。通过Xilinx公司的Virtex-6系列xc6vlx550T开发板对设计进行测试,实验结果表明,该结构在保持简洁性和可扩展性的同时,最高可提供9.73 GB/s的访存带宽,能够满足视频编解码算法数据访存的需求。     

Render2MPEG: A Perception-based Framework Towards Integrating Rendering and Video Compression

Currently 3D animation rendering and video compression are completely independent processes even if rendered frames are streamed on‐the‐fly within a client‐server platform. In such scenario, which may involve time‐varying transmission bandwidths and different display characteristics at the client side, dynamic adjustment of the rendering quality to such requirements can lead to a better use of server resources. In this work, we present a framework where the renderer and MPEG codec are coupled through a straightforward interface that provides precise motion vectors from the rendering side to the codec and perceptual error thresholds for each pixel in the opposite direction. The perceptual error thresholds take into account bandwidth‐dependent quantization errors resulting from the lossy com‐pression as well as image content‐dependent luminance and spatial contrast masking. The availability of the discrete cosine transform (DCT) coefficients at the codec side enables to use advanced models of the human visual system (HVS) in the perceptual error threshold derivation without incurring any significant cost. Those error thresholds are then used to control the rendering quality and make it well aligned with the compressed stream quality. In our prototype system we use the lightcuts technique developed by Walter et al., which we enhance to handle dynamic image sequences, and an MPEG‐2 implementation. Our results clearly demonstrate many advantages of coupling the rendering with video compression in terms of faster rendering. Furthermore, temporally coherent rendering leads to a reduction of temporal artifacts.     

Vector-quantization-based video codec for software-only playback on personal computers

This paper discusses a video compression and decompression method based on vector quantization (VQ) for use on general purpose computer systems without specialized hardware. After describing basic VQ coding, we survey common VQ variations and discuss their impediments in light of the target application. We discuss how the proposed video codec was designed to reduce computational complexity in every principal task of the video codec process. We propose a classified VQ scheme that satisfies the data rate, image quality, decoding speed, and encoding speed objectives for software-only video playback. The functional components of the proposed VQ method are covered in detail. The method employs a pseudo-YUV color space and criteria to detect temporal redundancy and low spatial frequency regions. A treestructured-codebook generation algorithm is proposed to reduce encoding execution time while preserving image quality. Two separate vector codebooks, each generated with the treestructured search, are employed for detail and low spatial frequency blocks. Codebook updating and sharing are proposed to further improve encoder speed and compression.     

Real-time video watermarking techniques robust against re-encoding

This paper presents a real-time watermarking codec that is robust against re-encoding attacks for high-definition videos. The codec uses a segmentation function and texture detector techniques for applying real-time watermarking to human visual systems. Experimental results confirm that the proposed scheme satisfies the requirements of invisibility, real-time processing, and robustness against format conversion and low bit-rate encoding. The proposed algorithm has the advantages of simplicity, flexibility, and low computational burden; thus, it is a suitable candidate for many novel and interesting applications such as video fingerprinting for set-top boxes, Internet protocol television, personal video recorders, and satellite boxes.     

交互式多点视频会议系统的纯软件实现

介绍了一种低成本高质量的交互式多点视频会议系统的软件实现方法。该系统参照了ITU制订的H．332协议，采用分布式松耦合的系统结构，大大地提高了系统的规模扩展性。在音视频数据编解码方面，该系统利用了微软公司Windows2000操作系统内置的软件Codec，具体的实现用到了微软公司的：DirectShow技术。由于该系统选用了目前最优秀的低码率图像编码标准MPEG-4来进行视频数据的编解码，取得了令人满意的主观视频质量。     

Perceptual depth compression for stereo applications

Conventional depth video compression uses video codecs designed for color images. Given the performance of current encoding standards, this solution seems efficient. However, such an approach suffers from many issues stemming from discrepancies between depth and light perception. To exploit the inherent limitations of human depth perception, we propose a novel depth compression method that employs a disparity perception model. In contrast to previous methods, we account for disparity masking, and model a distinct relation between depth perception and contrast in luminance. Our solution is a natural extension to the H.264 codec and can easily be integrated into existing decoders. It significantly improves both the compression efficiency without sacrificing visual quality of depth of rendered content, and the output of depth‐reconstruction algorithms or depth cameras.     

基于Lagrange的H．264率失真编码优化算法

为了进一步提高编码速度，促进视频编码技术在多媒体通信领域的实际应用，本文对率失真视频编码的关键算法进行了深入的研究并提出了其优化方法，并从信息论理论出发，着重围绕图像压缩的理论，利用率失真特征数学模型、拉格朗日乘子法，对目前新一代的H．264视频标准进行编码算法模式选择，试图从最根本的理论角度探讨信源编码，以便得到更高的压缩比、更好的图像质量和更快的编码速度。最后，利用本文提出的编码模式优化算法，对H．264的JM61e（JUT Test Model）系统测试模型的性能进行全面测试。