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Future multimedia communication systems have to support the user‘s needs, the terminal capabilities, the content specification and the underlying networking technologies. The related protocols and applications must be designed from this integration perspective in a cross-layer centric manner. In this paper, we propose an implementation of a streaming service (e.g.,Television over IP service) with a unified QoS management concept that enables an IP driven integration of different system components (terminal, user, content, and network). The MPEG-21 framework is used to provide a common support for implementing and managing the end-to-end QoS. The main focus of this paper is on the architecture design, protocols specification and implementation evaluation. Performance evaluations using PSNR and SSIM objective video quality metrics show the benefit of the proposed MPEG-21-enabled cross-layer adaptation. 相似文献
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INTRODUCTION Video streaming service nowadays enjoys ex- plosive adoptions over all kinds of underlying net- works. To enjoy the freedom of tether-less connection over the wireless local area network (WLAN), we need to overcome many challenges of unstable wire- less channel due to fading, interference and so on. The scarce and fluctuating available bandwidth (together with time-varying delays and random/burst losses) can cause the video quality at the streaming client to be seriously deg… 相似文献
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The scalable extension of H.264/AVC, known as scalable video coding or SVC, is currently the main focus of the Joint Video Team‘s work. In its present working draft, the higher level syntax of SVC follows the design principles of H.264/AVC.Self-contained network abstraction layer units (NAL units) form natural entities for packetization. The SVC specification is by no means finalized yet, but nevertheless the work towards an optimized RTP payload format has already started. RFC 3984, the RTP payload specification for H.264/AVC has been taken as a starting point, but it became quickly clear that the scalable features of SVC require adaptation in at least the areas of capability/operation point signaling and documentation of the extended NAL unit header. This paper first gives an overview of the history of scalable video coding, and then reviews the video coding layer (VCL)and NAL of the latest SVC draft specification. Finally, it discusses different aspects of the draft SVC RTP payload format, including the design criteria, use cases, signaling and payload structure. 相似文献
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王明松 《鞍山师范学院学报》2006,8(6):49-51
为了满足人们对能够使用任何设备在任何时间、任何地点都能访问多媒体内容的要求,MEPG-21多媒体框架被提出.文章简要介绍了MPEG-21多媒体应用框架,之后提出了一个多媒体内容的适应性框架,最后对传输适应性多媒体内容的协议做了阐述. 相似文献
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In this paper, we propose a novel optimal quality adaptation algorithm for MPEG-4 fine granular scalability (FGS) stream over wired network. Our algorithm can maximize perceptual video quality by minimizing video quality variation and increasing available bandwidth usage rate. Under the condition that the whole bandwidth evolution is known, we design an optimal algorithm to select layer. When the knowledge of future bandwidth is not available, we also develop an online algorithm based on the optimal algorithm. Simulation showed that both optimal algorithm and online algorithm can offer smoothed video quality evolution. 相似文献
6.
Frame loss error concealment for SVC 总被引：2，自引：0，他引：2
INTRODUCTION Real-time transmission of video data in network environments, such as wireless and Internet, is a challenging task, as it requires coding efficiency, network friendliness and error robustness. Scalability is a possible solution for network adaptive applica- tions. The Scalable Extension of H.264/AVC (SVC) (JVT of ISO/IEC MPEG & ITU-T VCEG, 2005b) aims at achieving both high compression performance and adaptivity for video delivery over heterogeneous networks. SVC… 相似文献
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Dynamic adaptation of multimedia content is seen as an important feature of next generation networks and pervasive systems enabling terminals and applications to adapt to changes in e.g. context, access network, and available Quality-of-Service (QoS) due to mobility of users, devices or sessions. We present the architecture of a multimedia stream adaptation service which enables communication between terminals having heterogeneous hardware and software capabilities and served by heterogeneous networks. The service runs on special content adaptation nodes which can be placed at any location within the network. The flexible structure of our architecture allows using a variety of different adaptation engines. A generic transcoding engine is used to change the codec of streams. An MPEG-21 Digital Item Adaptation (DIA) based transformation engine allows adjusting the data rate of scalable media streams. An intelligent decision-taking engine implements adaptive flow control which takes into account current network QoS parameters and congestion information. Measurements demonstrate the quality gains achieved through adaptive congestion control mechanisms under conditions typical for a heterogeneous network. 相似文献
8.
H.264/MPEG-4 AVC standard appears highly competitive due to its high efficiency, flexibility and error resilience. In order to maintain universal multimedia access, statistical multiplexing, or adaptive video content delivery, etc., it induces an immense demand for converting a large volume of existing multimedia content from other formats into the H.264/AVC format and vice versa. In this work, we study the remultiplexing and resynchronization issue within system coding after transcoding, aiming to sustain the management and time information destroyed in transcoding and enable synchronized decoding of decoder buffers over a wide range of retrieval or receipt conditions. Given the common intention of multiplexing and synchronization mechanism in system coding of different standards, this paper takes the most widely used MPEG-2 transport stream (TS) as an example, and presents a software system and the key technologies to solve the time stamp mapping and relevant buffer management. The solution reuses previous information contained in the input streams to remultiplex and resynchronize the output information with the regulatory coding and composition structure. Experimental results showed that our solutions efficiently preserve the performance in multimedia presentation. 相似文献
9.
结合空时OFDM和转换编码技术,提出了一种无线衰落信道下具有可分级转码能力的鲁棒视频传输方法.采用可分级转码器将高质量的MPEG-2压缩视频转换为低码率、低分辨率MPEG-4可分级码流来满足网络带宽和终端设备显示的要求.在接收端采用一种层干扰抑制算法,使得分层空时OFDM系统不同层的传输性能存在差异,从而使系统具有不对等保护能力.根据分级码流的重要程度不同,将转码输出的可分级码流分别由分层空时编码OFDM系统的不同层来实现视频的鲁棒传输.实验结果表明:在典型的随机突发错误的无线环境下,提出的具有可分级转码能力的系统的视频传输性能优于传统的非分级转码的视频传输系统. 相似文献
10.
In this paper, we propose a novel optimal quality adaptation algorithm for MPEG-4 fine granular scalability (FGS) stream over wired network. Our algorithm can maximize perceptual video quality by minimizing video quality variation and increasing available bandwidth usage rate. Under the condition that the whole bandwidth evolution is known, we design an optimal algorithm to select layer. When the knowledge of future bandwidth is not available, we also develop an online algorithm based on the optimal algorithm. Simulation showed that both optimal algorithm and online algorithm can offer smoothed video quality evolution. 相似文献
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INTRODUCTION Low latency video transmission is very de manding in terms of the performance of all layers i the protocol stack. Over the last decade, research ha focused on enhancements of each individual laye without considering cross-layer interactions. Adapt ing video coding to the channel/network condition and technologies (and vice versa) (Girod et al., 2002 via the cross-layer exchange of information has onl recently been investigated. van der Schaar et al.(200 developed a cross-laye… 相似文献
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INTRODUCTION Video content will be the main contributor to the future traffic in multimedia applications. Camcorders, digital cameras and lately mobile phones with video capturing capabilities have resulted in a wide spreading of multimedia to the masses. Quality of the captured/rendered videos is likely to be the major determining factor in the success of the new multi- media applications as well as product differentiation. Video processing chain includes video capturing, video pre-proce… 相似文献
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INTRODUCTION Modern videoconferencing systems allow two o more participants to communicate with each other in real-time using both audio and video. Conventionally when more than two participants are present, a sta configuration is generally employed, wherein a Mul tipoint Conferencing Unit (MCU), or bridge, is util ized to connect to all participants and coordinat communications between them. The general archi tecture is shown in Fig.1. Fig.1 Multipoint videoconferencing system Network… 相似文献
15.
本文详细讨论了一种基于嵌入式系统的新型网络视频监控终端的设计方法.该监控终端以S3C4510B微处理器为核心,采用MPEG-4硬压缩技术,整合了网络视频接入器和高速球二者的功能.由于终端设计合理,性价比高,它为远程视频监控系统提供了一种很好的前端解决方案. 相似文献
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MPEG-2l多媒体框架是正在制订中的关于多媒体信息发布和使用的国际标准。它是一个支持通过异构终端和网络,使用户透明地、广泛地、交互地使用多媒体信息资源的综合性的技术标准。本文简要的介绍了MPEG-21多媒体框架标准的研究目标和用户需求,阐述了MPEG-21多媒体框架标准的基本要素,最后重点讨论了MPEG-21在教育教学中的应用。 相似文献
17.
黎杨梅 《武汉职业技术学院学报》2012,(5):68-72
介绍了使用局域网组播技术和Directshow多媒体开发框架实现多方视频会议系统的方法。系统引入了会议管理服务器以控制多媒体数据在网络中的接入和访问,使网络不会由于多媒体数据的激增而发生拥塞,从而保证服务质量。系统使用了面向对象的方法和UML语言,分析和设计了各个模块。系统的视频部分采用了MPEG-4编解码技术,音频数据留采用了G.729编解码方法。根据该设计方案,完成了该系统的设计和开发,实现了多人同时通讯的模拟视频会议功能。 相似文献
18.
Jie Chi Yang 《Interactive Learning Environments》2013,21(4):369-385
Recently, multimedia-based learning is widespread in educational settings. A number of studies investigate how to develop effective techniques to manage a huge volume of video sources, such as summarization and recommendation. However, few studies examine how these techniques affect learners' perceptions in multimedia learning systems. This article aims to examine learners' perceptions for summarization and recommendation, with an emphasis on the perspective of prior experience. In this study, we developed a multimedia content summarization and recommendation system, which can automatically extract summaries from raw video sources and recommend suitable video content to learners through emails. The results demonstrate that learners' prior experience and preferences for the presentation of document types affect their perceptions, including the enhancement of interests, the ease of information acquisition and the intention for the further use of the system. Finally, the findings are applied to develop a framework that can support for the design of multimedia learning systems. 相似文献
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Gheorghita Ghinea Sherry Y. Chen 《British journal of educational technology : journal of the Council for Educational Technology》2003,34(4):393-406
Multimedia technology has been widely used in web‐based instruction, but previous studies have indicated that individual differences, especially cognitive styles, have significant effects on users’ preferences with respect to presentation of multimedia content. However, such research has thus far neglected to examine the effect of cognitive styles on users’ subjective perceptions of multimedia quality. This study aims to examine the relationships among users’ cognitive styles, the multimedia Quality of Service (QoS) delivered by the underlying network, and Quality of Perception (QoP), which encompasses user levels of enjoyment and understanding of the informational content provided by multimedia material. Accordingly, 132 users took part in an experiment in which they were shown multimedia video clips presented with different values of two QoS parameters (frame rate and colour depth). Results show that, whilst the two QoS parameters do not impact user QoP, multimedia content and dynamism levels significantly influence the user understanding and enjoyment component of QoP. 相似文献
20.
We propose a novel prioritized intra refresh method for the wireless video communication. The proposed method considers the characteristics of the human visual system, the error-sensitivity of the bitstream, and the state of the time-varying wireless channel jointly. An expected perceptual distortion model was used to adjust the intra refresh rate adaptively. This model consists of the perceptual weight map based on an attention model, the bit error probability map based on bitstream size, and the dynamic channel state information （CSI）. Experimental results indicate that, compared with other intra refresh methods that consider only the content of the video or the CSI, the proposed method improves the average peak signal-to-noise ratio （PSNR） of the whole frame by about 0.5 dB, and improves the average PSNR of the attention-area by about 0.8 dB. 相似文献