基于IP网络的视频流QoS解决策略

基于IP网络的视频业务对视频流传输的QoS提出了新的要求,在分析了IP网络和视频流传输系统的QoS要求后,详细介绍了基于视频分级压缩编码、终端控制和网络控制等主要的解决策略。     

VBR视频在IPTV点播业务中的应用

通过对VBR视频流量进行工程建模,结合IPTV用户点播时间间隔分析聚合VBR视频流量特性,研究表明在兼容现有终端和平台系统的情况下,即使不采用任何视频平滑处理,在IPTV点播业务中通过应用大规模VBR视频流的统计随机特性进行自我平均(self-average)也可获得30%~50%的统计增益,并通过大规模现场试验验证了VBR视频自平均特性在IPTV点播业务中的可行性和有效性。     

诠释华为媒体云战略 推出广电领域“云-管-端”新品——华为广电领域新品发布会暨面向三网融合的媒体云平台研讨会

近年来，广电网络的发展受到互联网技术、新媒体技术和智能终端技术高速发展的影响，高清、交互视频业务爆炸式增长，网络中的视频流量激增，不仅给传统视频网络带来巨大压力，也对未来视频网络的形态提出了更高的要求，媒体网络走向三网融合成为一种必然的发展趋势。作为国内外知名公司，     

基于势力场博弈的无线网络视频流速率控制模型

多媒体通信中如何对视频流量速率进行高效公平分配是提升无线网络性能的重要手段.应用势力场博弈模型来研究无线网络视频流速率分配机制,根据视频流特性建立了基于流量信噪比和流量速率为参数的势力场效用函数,提出了基于势力场博弈的无线网络视频流速率控制模型.证明了模型的纳什均衡存在性及唯一性,并提出了势力场博弈模型纳什均衡的分布式求解算法.数值仿真验证了势力场博弈的纳什均衡存在性,仿真结果表明了提出的模型能保证不同视频流量间公平的速率分配,且由于提出的算法执行方式是分布式的,能有效减轻网络的负载.     

自相似VBR视频源业务流的建模和仿真

该文在对实际VBR MPEG视频源统计特性分析的基础上,参照分形高斯噪声自相似(Fractional Gaussian Noise Self-Similar)模型产生方法,实现了对ATM网络中最主要业务流VBR视频源流的建模,提出了改进方法,使得对实际源的仿真不仅考虑到了长期相关性,同时也兼顾到了短期相关性。仿真结果表明,经改进的自相似VBR视频源模型是一种较理想的模型。     

VBR视频流多重分形建模

该文在小波域多重分形基础上,研究了基于分布、点集(PM)分布的多重分形小波模型(MWM)的性能,并提出了一种具有更好的逼近性能的混合PM-分布形式;同时,针对VBR视频流的I,P,B帧周期分布特性,充分利用异种帧相关性,建立了考虑帧间相关性的混合多重分形小波VBR视频流量模型CMWM(Composite MWM)。仿真试验表明,与传统的短相关和长相关模型相比,具有多重分形特性的CMWM能更加精确地描述MPEG视频业务的统计特性和排队性能。     

基于Android的ONVIF协议网络视频监控客户端的接口研究

随着网络视频监控系统的快速发展,其相关产品愈益丰富,而系统设备间的互通性成为迫切需要解决的问题。基于此种情况,研究了ONVIF协议提供的网络视频监控客户端接口,在基于Android的智能手机上完成了对ONVIF网络摄像头的设备发现和设备管理,实现了视频流的播放和对摄像头的云台控制功能。在设计的过程中,首先利用WS-Discovery方案完成设备发现功能,在此基础上实现设备管理、获取视频流地址和云台控制功能,最后通过移植FFMPEG完成对RTSP视频流的解码播放。最后测试结果表明设计的客户端能与前端网络摄像头通信,能控制云台实现运动和变焦功能,获取的视频流能正常解码播放。     

广东联通将推出“视频流媒体”预热3G市场

日前,广东联通透露,今年中国联通将推出基于CDMA1X网络的“视频流媒体”业务,其中包括视频音乐、视频新闻、视频体育和其他视频娱乐、电影新片预告、电视转播、视频点播在内的多项视频服务内容,为全面进军3G奠定基础。据广东联通市场部相关人员介绍,联通“视频流媒体”是基于CD     

UWB无线视频传输关键技术研究

为了方便的研究无线视频在UWB传输过程中的丢包率、吞吐量、时延,对UWB信道模型进行了研究,使用NS2构建了UWB的网络模型。网络模型配置了模拟网络拓扑结构、各层使用的协议,确定了链路的基本特性,从而可以模拟无线视频传输的UWB环境。构建的网络模型可以模拟压缩编码后视频流的无线传输过程。     

一个基于速率控制的Internet视频流服务方案

由于视频流服务对于网络服务质量有着较高的要求,而现有的Internet所提供的是尽力而为的服务,无法保证数据的实时传输。该文设计了一个用于Internet上视频流的端到端传输方案.整个方案设计的目的是在网络本身缺乏服务质量保证的条件下尽可能达到最好的视频传输质量。根据可用带宽估计和网络信息反馈,系统对发送速率进行调整,并提供两种视频流服务:存储视频和实时视频。仿真结果表明方案的性能良好,能满足Internet视频流的需求。     

The transmission of MPEG‐2 VBR video under usage parameter control

This paper studies the transmission of MPEG‐2 VBR video over ATM network under usage parameter control. The idea is to seek a compromise between the network utilization and the quality of video service by applying UPC‐based rate control strategies to the video source. A modified leaky bucket algorithm is proposed to calculate the constraints on the bit‐rate guaranteeing conformance to peak cell rate, sustainable cell rate and burst tolerance usage parameters. Two rate control strategies, one for real‐time generated video coding and the other for pre‐compressed video, are proposed for MPEG‐2 VBR video. The rate control strategies control the video source to generate traffic conforming to the constraints on the bit rate. The experimental results show that both the UPC‐based rate control strategies can provide lossless transmission from the source perspective as well as to reduce the burstiness of the traffic. To keep within the bit‐rate allowed, the control method uses coarser quantization to maintain better picture quality than that by removing the number of AC transformed coefficients. The slight degradation of picture quality caused by the source rate control is preferable than the severe drop of picture quality caused by the cell loss at UPC. Copyright © 2001 John Wiley & Sons, Ltd.     

Modeling one- and two-layer variable bit rate video

This paper presents a source model for VBR video traffic. A finite-state Markov chain is shown to accurately model one- and two-layer video of all activity levels on a per source basis. Our model captures the source dynamics, including the short-term correlations essential for studying network performance. The modeling technique is shown to be applicable for both H.261 and MPEG2 encoded video of a variety of activity levels. The traffic model is shown in a simulation study to be able to accurately characterize both the single-source buffer occupancy over a wide range of buffer sizes and the multiplexing behavior. The VBR video model is also used to model the enhancement layer of two-layer SNR scalable video. We show that two-layer encoding has significantly better statistical multiplexing gains than one-layer video, particularly when the network admits calls based on a leaky-bucket characterization     

实时性MPEG视频源的图片组内平滑算法

本文对实时性的ＭＰＵＥＧ视频源进行了平滑研究,通过分析ＭＰＥＧ视频编码的特点和实时性ＶＢＲ视频对延迟的严格要求,提出实时性ＭＰＥＧ视频在图片组（ＧＯＰ）内平滑已接近最佳平滑的观点,并推导了图片组内平滑的上限速率和下限速率公式,设计了选择最佳速率的算法,最后使用两组代表不同应用的ＭＰＥＧ视频样本数据进行了仿真实验。实验表明：图片组内平滑算法与文献上其它算法相比,在理论上可取得几乎相同的理想平滑效果,     

Smoothing and transporting video in QoS IP networks

Real‐time traffic such as voice and video, when transported over the Internet, demand stringent quality of service (QoS) requirements. The current Internet as of today is still used as a best effort environment with no quality guarantees. An IP‐based Internet that supports different QoS requirements for different applications has been evolving for the past few years. Video streams are bursty in nature due to the instant variability of the video content being encoded. To help mitigate the transport of bursty video streams with minimal loss of information, rate‐adaptive shapers (RASs) are usually being used to reduce the burstiness and therefore help preserve the desired quality. When transporting video over a QoS IP network, each stream is classified under a specific traffic profile to which it must conform, to avoid packet loss and picture quality degradation. In this paper we study, evaluate and propose RASs for the transport of video over a QoS IP network. We utilize the encoding video parameters for choosing the appropriate configuration needed to support the real‐time transport of Variable Bit Rate (VBR) encoded video streams. The performance evaluation of the different RASs is based on the transport of MPEG‐4 video streams encoded as VBR. The performance is studied based on looking at the effect of various parameters associated with the RASs on the effectiveness of smoothing out the burstiness of video and minimizing the probability of packet loss. Copyright © 2005 John Wiley & Sons, Ltd.     

Study of the impact of MPEG-1 correlations on video-sourcesstatistical multiplexing

Variable bit-rate (VBR) video is expected to become increasingly important with the large scale deployment of broadband-integrated services networks (B-ISDNs). While the modeling of VBR video sources has received significant attention, there is no widely accepted model which lends itself to mathematical analysis. Furthermore, new video compression standards are emerging, such as the MPEG family. A detailed statistical analysis of a long sample of a movie encoded with an MPEG-1 algorithm highlights that traffic generated by an MPEG-1 encoder has both a high degree of burstiness (peak/average ratio greater than five) and a strong long-term correlation (positive correlation lasts for ten/twenty minutes). In this paper, we propose and analyze a Markov model which captures both the burstiness and the temporal dependencies of MPEG traffic. Furthermore, we show that our model is a flexible traffic generator which is suitable for studying statistical multiplexing issues. Specifically, we study both the multiplexing of a VBR video source with low priority traffic and the multiplexing of several VBR video sources. The results obtained show that the long-term correlation significantly affects the tail of the delay distribution even for lightly loaded networks. The presence of a long range dependence in the MPEG traffic significantly reduces the gain in terms of network utilization which can be achieved with statistical multiplexing of i.i.d. sources     

MPEG coding for variable bit rate video transmission

For real-time transmission of broadcast-quality video on ATM-based B-ISDN, the intraframe to interframe ratio and the quantizer scale are two key parameters that can be used to control a video source in a network environment. Their impact on the traffic characteristics of the coder provides insights into the cell arrival process for an MPEG source. The authors obtain video source models for coders that utilize a standard algorithm that can be applied to a multitude of video services. The output stream of a video coder, which complies with the Motion Pictures Expert Group (MPEG) coding standard, is studied with an National Television Systems Committee (NTSC) quality video sequence as the input. Because the MPEG video coding algorithm has been proposed for a variety of applications, they also investigate the effect of changing the coding parameters on the statistics of interest     

Performance modeling of MPEG‐4 video streaming over IEEE 802.11 using distribution coordination function

Delivering video streaming over wireless Internet is becoming increasingly popular. However, most of the research studies focused on the modeling analysis of system performance such as saturation throughput and channel utilization. Perceived quality of video streaming cannot be assessed solely based on the results of analytical models. In this paper, we propose a model to assess the perceived quality of MPEG‐4 video streaming over IEEE 802.11 distribution coordination function (DCF)‐based wireless local area networks. The analysis of our proposed model considers not only effects of losses such as collision loss from channel access competition but also wireless loss caused by wireless interferences. Moreover, the impact of the loss of specific MPEG‐4 video frames is also taken into account in the performance analysis. The model was validated by comparing our performance results with results obtained from simulation and analytical models. The results show that our proposed model is able to predict the perceived quality of MPEG‐4 video streaming over DCF‐based WLAN more accurately than other models. Copyright © 2010 John Wiley & Sons, Ltd.     

Robust Video Transmission With Distributed Source Coded Auxiliary Channel

We propose a novel solution to the problem of robust, low-latency video transmission over lossy channels. Predictive video codecs, such as MPEG and H.26x, are very susceptible to prediction mismatch between encoder and decoder or “drift” when there are packet losses. These mismatches lead to a significant degradation in the decoded quality. To address this problem, we propose an auxiliary codec system that sends additional information alongside an MPEG or H.26x compressed video stream to correct for errors in decoded frames and mitigate drift. The proposed system is based on the principles of distributed source coding and uses the (possibly erroneous) MPEG/H.26x decoder reconstruction as side information at the auxiliary decoder. The distributed source coding framework depends upon knowing the statistical dependency (or correlation) between the source and the side information. We propose a recursive algorithm to analytically track the correlation between the original source frame and the erroneous MPEG/H.26x decoded frame. Finally, we propose a rate-distortion optimization scheme to allocate the rate used by the auxiliary encoder among the encoding blocks within a video frame. We implement the proposed system and present extensive simulation results that demonstrate significant gains in performance both visually and objectively (on the order of 2 dB in PSNR over forward error correction based solutions and 1.5 dB in PSNR over intrarefresh based solutions for typical scenarios) under tight latency constraints.      

Traffic shaping, bandwidth allocation, and quality assessment forMPEG video distribution over broadband networks

This article provides an overview of residential video delivery systems and presents the applications, benefits, and challenges of using VBR MPEG video encoding in broadband video distribution networks. The network resources required to transmit stored variable-rate MPEG can be reduced by properly analyzing and smoothing the video stream before transmission. A scheduling technique is presented which selects a traffic contract for a pre-encoded MPEG video stream with the criteria of minimizing network resources and maintaining video quality. Several effective bandwidth metrics are discussed and used to model the potential savings in network resources for the shaped streams