• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.15 no.8
• /
• pp.1743-1749
• /
• 2011

The multimedia data for video-on-demand(VOD) service has large, continuous and real time characteristics. The frequent disk I/O operations takes much time and decrease the system performance in multimedia services. Therefore the efficient buffer management is needed in order to reduce the disk accesses to multimedia data. This paper addresses how to increase the buffer hit ratio and the number of users in a multimedia service like VOD by increasing the utility of buffer. This paper also simulated various resource management algorithms and strategies and evaluated, compared and analyzed their performances.

• Journal of KIISE:Computer Systems and Theory
• /
• v.34 no.4
• /
• pp.138-144
• /
• 2007

With recent proliferation of video-on-demand services, caching in a multimedia streaming server is becoming increasingly important. Previous studies have shown that request interval based caching and its extension for considering different video popularity performs well in various streaming environments. In this paper, we show that block level refinement of this existing scheme can further improve the performance of streaming servers. Trace driven simulations with real world VOD traces have shown that the proposed scheme improves the cache hit rate and the startup latency.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.9B
• /
• pp.1652-1660
• /
• 1999

One of the most important goals in VOD servers is to provide services to more clients with services which clients request. In order to provide service efficiently and rapidly, though considering a few of policies, efficient placement of data when they are stored is direct cause to improve efficiency of retrievals. In this paper, we propose a efficient placement policy, encoded video data being stored in clustered VOD servers. In the proposed placement policy, partitioning a large disk array into smaller disk groups which consists of a few of disks with similar performances, specially disk I/O bandwidth. In last chapter, we compare proposed placement policy with conventional policies, and show the results of improved performances with proposed policy.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.39B no.7
• /
• pp.467-476
• /
• 2014

Recently, various services which use the fused form of broadcasting and communication are being offered over the Internet globally. To provide various interactive services through connected smart TV on wired or wireless network, the seamless multimedia service is key feature. In this paper, Dynamic Adaptive Streaming over HTTP (DASH)is adopted to develop cost-effective adaptive streaming system for Open Hybrid TV(OHTV) service. This system can provide seamless adaptive streaming service for IP VOD, Video Clips, Ad insertion which are defined in OHTV.

• Journal of Internet Computing and Services
• /
• v.8 no.2
• /
• pp.77-87
• /
• 2007

A typical VOD service allows that a number of remote clients playback a desired video from a large collection of videos stored in one or more video servers. The main bottleneck for a VOD service is the network bandwidth connecting to the VOD server to the client due to the high bandwidth requirements. Many previous researches have shown that VOD server can be greatly improved through the use of multicast, broadcast, or P2P scheme. Broadcast is one of the most efficient techniques because it can transmit a stream to many users without additional network bandwidth. But the broadcast has long latency time. In order to overcome the drawback, in this paper, we propose P2Prefix broadcast scheme that can solve the service latency time, which is the problem of broadcast scheme, by using P2P caching as well as minimizing the client buffer requirement.

• Electronics and Telecommunications Trends
• /
• v.10 no.3 s.37
• /
• pp.29-45
• /
• 1995

대화형 멀티미디어 서비스중에서 대표적인 VOD(Video on demand) 서비스 일반에 관한 표준제정이 DAVIC(Digital Audio-Visual Council)을 중심으로 한창 진행되고 있다. 본 고에서는 DAVIC에서 정하고 있는 시스템 기준모델을 각 구성요소별로 살펴보고 디지털 음성-영상 응용 및 서비스들간의 상호 운용성을 위해 현재 표준제정 중인 인터페이스와 프로토콜을 1995년 1월에 만들어진 초안과 3월의 그 수정판 (DAVIC 1.0)을 중심으로 상세히 소개하려고 한다.

• Journal of the Korea Society for Simulation
• /
• v.9 no.3
• /
• pp.65-75
• /
• 2000

In recent years, significant advances in computers and communication technologies have made multimedia services feasible. As a result, various queuing models and cost models on architecture and data placement for multimedia server have been proposed. However, these analytical techniques use only probabilistic models to represent the behavior of a system, and then they have several limitations like accuracy. Simulation is a viable alternative to analytical model. It avoids many of the limitations associated with analytical techniques, allowing for more precise representation of system attributes like workload in program code. In this paper, we propose a simulation test bed that can evaluate performance of real-time multimedia server by using simulation model.

• Journal of KIISE:Computing Practices and Letters
• /
• v.6 no.5
• /
• pp.505-512
• /
• 2000

In this paper, an adaptive multimedia synchronization scheme for VOD (Video On Demand) services in internet environments is proposed. This scheme considers the characteristics of MPEG (Moving Picture Expert Group) system stream. Consequently, the intra-synchronization is handled at the pack layer, and the inter-synchronization is handled at the packet layer. The proposed scheme can cope adaptively with variation of packet loss, jitter and client's playback capacity. If there are variations of the packet loss or client's playback capacity, the server will change the transmission rate by selective picture skip. The client can then adjust and control the playback time according to the variation of the network jitter. Our experimental results show that the proposed scheme can quickly adapt to the network condition, and can guarantee a better quality of service than the other existing schemes.

• Journal of the Korea Computer Industry Society
• /
• v.8 no.3
• /
• pp.197-206
• /
• 2007

The waiting delays of internet VOD users are inevitable in this policy since the services are not taken immediately upon requests but upon every scheduling points. An inefficient management of such delays makes an unfair service to users and increases the possibility of higher reneging rates. This paper proposes an efficient service scheduling scheme which improves the average waiting time of users requests and reduces the starvation problem of users requesting less popular movies. Experimental results of simulations show that the proposed scheme improves about 20 percentage of average waiting time and reduces significantly the starving requesters comparing with those of conventional methods such as FCFS and MQL.

• Journal of the Korea Computer Industry Society
• /
• v.6 no.3
• /
• pp.379-390
• /
• 2005

Intensive studies have been made in the area of VOD server Multimedia files in the VOD sever are characterized with the large volume of data, the requirements of synchronization and real-time playback of streams. The basic goal of the study is to find an efficient mechanism to allow maximum number of users under the limited resources such as Buffer size and disk bandwidth. we propose a efficient $pre\_fetching$ policy for multimedia services with dynamic monitoring and management of VOD sever resources. Simulation results show that the rate of buffer usage and service time of proposed scheme are about $28\%$ performance improved than that of traditional methods. This implies that our method can allow much more users for given resources.