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1.
The major drawback of the existing cluster placement scheme is the long response time caused by admission control if the
number of clusters and the number of users are large. A circular skip-cluster placement scheme is proposed to reduce the size
of the data buffer as well as the system response time. Furthermore, the popularity of each video is different in the real
world. We propose a new popularity-based data allocation scheme to allocate data units within a cluster such that the corresponding
data units of these popular videos are stored in those cylinders at one end of each cluster. Due to a higher spatial locality
within these hot cylinders, some data units requested by the users are stored in the same cylinder such that one seek operation,
one rotation, and one transfer operation are required to retrieve these data units. Therefore, the time required to retrieve
data for these requests can be reduced, thus also reducing the system response time. Based on our results, the buffer size
and the system response time can be reduced by half or more. These findings are essential for constructing video-on-demand
systems that provide satisfactory performance. 相似文献
2.
For admission control in real-time multimedia systems, buffer space, disk bandwidth and network bandwidth must be considered.
The CBR-based mechanisms do not use system resources effectively, since media data is usually encoded with VBR compression
techniques. We propose an admission control mechanism based on a VBR data model that has a dynamic period length. In our mechanism,
the period can be adaptively changed to maximize the performance, considering both disk bandwidth and buffer space. To compare
the performance, extensive simulations are conducted on RR, SCAN, and GSS schemes which have the dynamic period length and
the static period length. 相似文献
3.
4.
视频存储分配技术在视频服务器主要技术之一,对VOD应用性能起决定性作用。本文提出一种视频存储模式的定义和基于矩阵的视频存储模式,在该模式中,采用三层结构存储基于矩阵分割的视频流,实现了VOD系统的无延迟即点即播,同时通过在视频流GOP中减少B帧的方法,减少复制数据段的数目,从而减少系统的内存需求。实验表明,该视频存储模式是有效可行的。 相似文献
5.
Andrew Brampton Andrew MacQuire Michael Fry Idris A. Rai Nicholas J. P. Race Laurent Mathy 《Multimedia Systems》2009,15(1):3-17
This paper presents a detailed characterisation of user behaviour for a series of interactive video experiments over a 12
month period, in which we served popular sporting and musical content. In addition to generic VCR-like features, our custom-built
video-on-demand application provides advanced interactivity features such as bookmarking. The dramatic impact of such functionality
on how users consume content is studied and analysed. We discuss in detail how this user behaviour can be exploited by content
distributors to improve user experience. Specifically, we study how simple dynamic bookmark placement and interactivity-aware
content pre-fetching and replication can reduce the impact of highly interactive media on CDN performance. 相似文献
6.
Towards capacity and profit optimization of video-on-demand services in a peer-assisted IPTV platform 总被引:1,自引:0,他引:1
Yih-Farn Chen Yennun Huang Rittwik Jana Hongbo Jiang Michael Rabinovich Jeremy Rahe Bin Wei Zhen Xiao 《Multimedia Systems》2009,15(1):19-32
This paper studies the conditions under which peer-to-peer (P2P) technology may be beneficial in providing IPTV services over
typical network architectures. It has three major contributions. First, we contrast two network models used to study the performance
of such a system: a commonly used logical “Internet as a cloud” model and a “physical” model that reflects the characteristics
of the underlying network. Specifically, we show that the cloud model overlooks important architectural aspects of the network
and may drastically overstate the benefits of P2P technology. Second, we propose an algorithm called Zebra that pre-stripes
content across multiple peers during idle hours to speed up P2P content delivery in an IPTV environment with limited upload
bandwidth. We also perform simulations to measure Zebra’s effectiveness at reducing load on the content server during peak
hours. Third, we provide a cost-benefit analysis of P2P video content delivery, focusing on the profit trade-offs for different
pricing/incentive models rather than purely on capacity maximization. In particular, we find that under high volume of video
demand, a P2P built-in incentive model performs better than any other model, while the conventional no-P2P model generates
more profits when the request rate is low. The flat-reward model generally falls in between the usage-based model and the
built-in model in terms of profitability except for low request rates. We also find that built-in and flat-reward models are
more profitable than the usage-based model for a wide range of subscriber community sizes.
Funding for J. Rahe’s research has been provided by AT&T Labs, the State of California under the MICR Oprogram, and by the
Toshiba Corporation.
Zhen Xiao is partially supported by China MOST project (2006BAH02A10). 相似文献
7.
A survey on peer-to-peer video streaming systems 总被引:2,自引:1,他引:2
Video-over-IP applications have recently attracted a large number of users on the Internet. Traditional client-server based
video streaming solutions incur expensive bandwidth provision cost on the server. Peer-to-Peer (P2P) networking is a new paradigm
to build distributed network applications. Recently, several P2P streaming systems have been deployed to provide live and
on-demand video streaming services on the Internet at low server cost. In this paper, we provide a survey on the existing
P2P solutions for live and on-demand video streaming. Representative P2P streaming systems, including tree, multi-tree and
mesh based systems are introduced. We describe the challenges and solutions of providing live and on-demand video streaming
in P2P environment. Open research issues on P2P video streaming are also discussed.
相似文献
Chao LiangEmail: |
8.
In this work, we introduce a cross-layer framework to favor the video-on-demand service in multi-hop WiMax mesh networks. We first propose a joint solution of admission control and channel scheduling for video streams. The proposed approach guarantees that the required data rate is achieved for video streams, which is crucial for multimedia streaming applications. An efficient and light-weight multicast routing technique is also proposed to minimize the bandwidth cost of joining a multicast tree. Furthermore, we adopt the Patching technique in the application layer to improve the capacity of the video server. Overall, the quality of the video-on-demand service is dramatically improved with the help of the efficient cooperation between the techniques proposed in different layers of the network. Simulation study shows that with the proposed approach, true video-on-demand in WiMax mesh networks can be achieved under high video request arrival rate. 相似文献
9.
视频点播是宽带网络上的一个重要的多媒体应用。本文介绍了如何在视频点播系统中进行仿真点播,并给出了一个具体实现,它有助于视频点播系统性能的测试与研究。 相似文献
10.
In this paper, we address the server selection problem for streaming applications on the Internet. The architecture we consider is similar to the content distribution networks consisting of geographically dispersed servers and user populations over an interconnected set of metropolitan areas. Server selection issues for Web-based applications in such an environment have been widely addressed; the selection is mostly based on proximity measured using packet delay. Such a greedy or heuristic approach to server selection will not address the capacity planning problem evident in multimedia applications. For such applications, admission control becomes an essential part of their design to maintain Quality of Service (QoS). Our objective in providing a solution to the server selection problem is threefold: first, to direct clients to the nearest server; second, to provide multiple sources to diffuse network load; third, to match server capacity to user demand so that optimal blocking performance can be expected. We accomplish all three objectives by using a special type of Linear Programming (LP) formulation called the Transportation Problem (TP). The objective function in the TP is to minimize the cost of serving a video request from user population x using server y as measured by network distance. The optimal allocation between servers and user populations from TP results in server clusters, the aggregated capacity of each cluster designed to meet the demands of its designated user population. Within a server cluster, we propose streaming protocols for request handling that will result in a balanced load. We implement threshold-based admission control in individual servers within a cluster to enforce the fair share of the server resource to its designated user population. The blocking performance is used as a trigger to find new optimal allocations when blocking rates become unacceptable due to change in user demands. We substantiate the analytical model with an extensive simulation for analyzing the performance of the proposed clustered architecture and the protocols. The simulation results show significant difference in overall blocking performance between optimal and suboptimal allocations in as much as 15% at moderate to high workloads. We also show that the proposed cluster protocols result in lower packet loss and latencies by forcing path diversity from multiple sources for request delivery. 相似文献