MPEG—4的码流传输：多媒体递送集成框架

重点讨论MPEG－4的递送技术抽象,即MPEG－4标准的第6部门：DMIF（多媒体递送集成框架）。首先解释了促使MPEG对递送技术进行抽象的动机,然后分析了DMIF体系结构的细节,讨论了通过DMIF递送多媒体内容的过程,最后介绍了DMIF版本2所作的一些扩展和IM1工作组对DMIF的实现,所讨论的一切都是针对多媒体内容的实时传输问题。     

MPEG码流在ATM网上传输问题的研究

MPEG码流在ATM网上传输是实现VOD要解决的问题。传输时码流的格式采用MPEG TS传输流,连接的类型为CBR,ATM适配层的类型为AAL5。将MPEG TS码流适配入ATM信元有两种发送的方式,即“PCR-aware”和“PCR-unaware”。对两种发送方式的效率计算表明,将2个TS包适配到8个ATM信元的“PCR-unaware”的发送方式是最优的。在“PCR-unaware”下接收端需要对所产生PCR延迟抖动进行补偿。     

MPEG2网络视频传输同步技术要点

一、MPEG2网络视频传输 网络视频传输是由数字视频处理、高速分组和网络实时同步传输等技术领域内的高科技发展而成的完整系统技术。网络技术迅速发展及其广泛的应用,使网络视频传输具有重大的经济效益和社会效益,是一项全新的高技术产业,并将对数字视频及网络技术的发展方向带来重大的影响。 MPEG2规范考虑到了多种应用的特点,能够通用于卫星广播、有线电视、数字地面广播、电影、可视电话、会议电视、多媒体邮递、网络数据库、点播电视等领域,其中基于网络的应用正占有越来越重要的地位。     

基于因特网的MPEG-4码流传输

在分析了因特网上进行了多媒体流传输的几个关键问题后，结合MPEG-4码流的特点，较深入地探讨了如何利用DMIF结构和RTP及其相关协议在因特网上传输MPEG-4码流。     

MPEG—2视频码流的拼接

1 前言 运动图像及其伴音的压缩编码技术是多媒体计算机、多媒体数据库、多媒体通信、标准清晰度电视(SDTV)、高清晰度电视(HDTV)及交互式电视(Interactive TV)等系统中的关键技术。国际标准化组织(ISO)1986年成立了制定运动图像及其伴音压缩编码标准的运动图像专家组MPEG(Moving Picture Expert Group)。1993年MPEG正式推出用于数字存储媒体、码率直到1.5Mbps的MPEG-1标准(ISO/IEC     

MPEG—2在ATM网络的传输

随着ATM技术和编码技术的成熟,ATM上可以传送增强型媒体,这使得视听业务的广泛应用成为可能,主要讨论在ATM网络上恒定比特率（CBR）或可变比特率（VBR）的MPEG-2的传输,这涉及到适配层的选择,MPEG-2帧的封装,ATM业务类型的选择等问题。     

MPEG—2MP＠ML码流合成的实时实现

视频编码器是高清晰度电视系统中的重要组成部分，而在采用十字划分方案的视频编码器的实时实现中，ＭＰＥＧ－２码流的合成是一项关键技术，在介绍采用十字划分方案的高清晰度电视视频编码器的基础上，着重介绍由四路ＭＰＥＧ－２ＭＰ＠ＭＬ码流一到路ＭＰＥＧ－２ＭＰ＠Ｈｉｇｈ１４４０码流的合成技术。     

MPEG—2视频编码数据流的头部信息

文章按照Ｈ．２６２标准的语法规定，对ＭＰＥＧ－２视频编码数据流中的头部信息进行了详细的说明。     

Transmission of MPEG-2 video streams over ATM

Experiments investigated the relationship between MPEG video quality and ATM network performance. Preliminary results reveal the effects of network impairments on video quality for MPEG-2 transport streams delivered over ATM. The issues in mapping variable-rate MPEG to ATM are also examined, including the trade-off between bandwidth savings and video quality     

基于ATM网络的MPEG-2 TS传输实现

ＭＰＥＧ－２传输流（ＭＰＥＧ－２ ＴＳ）在ＡＴＭ网络上的传输问题是基于ＡＴＭ网络视频点播的关键技术。分析了ＭＰＥＧ－２传输流的结构特性,并对ＡＴＭ网络适配层进行了描述,详细讨论了基于ＡＴＭ网络视频业务传输协议和传输的实现。     

An experimental study for transmitting MPEG-2 streams over ATM networks

This paper presents a comparative study of different techniques aiming at transmitting MPEG-2 streams over ATM networks, with emphasis on the presentation of practical results achieved on an experimental platform available at LSI, a laboratory of the University of São Paulo, Brazil. This study has the purpose to determine some tuning parameters for optimizing the implementation of distributed multimedia applications on different network technologies. The focus of this experimental study has been on non-native ATM techniques like “Classical IP over ATM” and “LAN Emulation”, as well as native ATM techniques based on direct access service primitives to AAL5. The influence of different parameters, like packet length, buffer size, CPU speed, on the resulting throughput has been studied. Furthermore, a testing tool is being developed for assessing the transmission of MPEG-2 streams based on the practical experience achieved so far. These results will permit the evaluation of different network technologies and also help in the development of distributed multimedia applications like video-on-demand, videoconferencing and telemedicine.     

Efficient Transmission of MPEG-2 Coded Video Traffic over ATM Networks

Video traffic is expected to account for a significant share of the traffic volume in the future asynchronous transfer mode (ATM) networks. MPEG-2 proposed by Moving Picture Expert Group is one of the most promising compression techniques for such applications. One of the critical issues in MPEG-2 is to realize effective variable bit rate (VBR) video transfer thorough ATM networks. The Leaky Bucket (LB) scheme has been widely accepted as the usage parameter control (UPC) mechanism to police the VBR sources. We proposed a new Adaptive Dynamic Leaky Bucket (ADLB) congestion control mechanism, which is based on the LB scheme. Unlike the conventional LB, the leak rate of the ADLB is controlled using delayed feedback information of available bandwidth sent by the network. This scheme allows sources to get varying amounts of bandwidth over time, while reserving a minimum guaranteed bandwidth (MCR) for the entire duration of the connection. At the time of congestion, the leak rate of the ADLB is adjusted according to the feedback indicating the currently available bandwidth to the connection. The simulation results show that the end-to-end cell transfer delay and cell loss of each source has been improved significantly.     

MPEG—2标准在基于ATM的VDT网络中的应用

主要讨论视频拨号音（ＶＤＴ）网络模型，及ＶＤＴ网络的ＭＰＥＧ－２标准数字视频信号在ＡＴＭ网中传输存在的问题和应用。     

An efficient protocol architecture for error-resilient MPEG-2 videocommunications over ATM networks

MPEG-2 video communications over ATM networks is one of the most active research areas in the field of computer communications. In the transmission process of a variable bit rate video signal over an ATM network, cells are inevitably exposed to delays, errors and losses due to the statistical multiplexing used in these networks. These phenomena affect the quality of the video signal and without adequate measures to control the propagation of the impairments the quality of the service may fall below acceptable levels. In this paper, we study the impact of cell losses on the quality of a MPEG-2 video sequence encoded in a variable bit rate mode. We introduce a set of control mechanisms at different levels of the protocol architecture to be used in MPEG-2-based video communications systems using ATM networks as their underlying transmission mechanism. Our results (using different video sequences) show the effectiveness to improve the video quality by using a structured set of control mechanisms to overcome for the loss of cells carrying VBR MPEG-2 video streams. We argue that in order to be able to create video systems able to cope with cell losses encountered in computer communications systems, a structured set of error-resilient protocol mechanisms is needed     

MPEG-2 ATM接入及其实现

通过ＡＴＭ网络提供视频点播业务（ＶＯＤ）是目前设备生产厂商和初步服务提供商所关注的一个热点问题，也是各个国际标准化组织研究的中心问题，本文就目前已达成共识的ｐｉｅｃｅ－ｗｉｓｅ方案进行了讨论，并给出了其具休贩框图。     

Forward error control for MPEG-2 video transport in a wireless ATM LAN

The possibility of providing multimedia services to mobile users has led to interest in designing broadband wireless networks that can guarantee quality of service for traffic flows. However, a fundamental problem in these networks is that severe losses may occur due to the random fading characteristics of the wireless channel. Error control algorithms which compensate for these losses are required in order to achieve reasonable loss rates. In this paper, the performance of error control based on forward error correction (FEC) for MPEG-2 video transmission in an indoor wireless ATM LAN is studied. A random bit error model and a multipath fading model are used to investigate the effect of errors on video transport. Combined source and channel coding techniques that employ single-layer and scalable MPEG-2 coding to combat channel errors are compared. Simulation results indicate that FEC-based error control in combination with 2-layer video coding techniques can lead to acceptable quality for indoor wireless ATM video.Work performed while the author was at AT&T Bell Laboratories on a D.O.E. fellowship program.     

MPEG-2 over ATM for video dial tone networks: issues and strategies

Market growth for PC multimedia and digital video owes largely to the rapid adoption of ISO compression standards by the industry. For video dial tone (VDT) services, the MPEG-2 set of standards have clearly emerged as the preferred coding method for VDT networks. For point-to-point switched video or multimedia connections, ATM has emerged as the technology of choice for switching and transport. This article describes how compressed digital video is transported over a VDT network, what some of the issues are, and how they are being addressed by the industry. It describes a generic VDT reference architecture, and the delivery method of video and multimedia information over such a network