• International Journal of Advanced Culture Technology
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• v.2 no.1
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• pp.14-19
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• 2014

In this paper, we propose a stream based patching technique in order to reduce demands of network output bandwidth required to provide the true video-on-demand (VoD) service in a Multimedia server. The proposed scheme calculates required streams to clients accurately by analyzing temporal relationships between already arrived requests in a multimedia server and still progressing streams, and then transmits streams freshly. Since our stream based patching technique induces new linking stream which is playing a link role between long and short patching streams, it reduces demand of network output bandwidth required to provide the true VoD service in a multimedia server. Accordingly, we know that the proposed scheme improves service latency and defection rate than those of existing patching technique by a simulation study.

• Journal of the Korea Society for Simulation
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• v.15 no.2
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• pp.23-29
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• 2006

This paper studies the Internet stream server which serves multimedia stream services such as VoD and MoD. The Internet multimedia stream server is developed to provide 50 users with continuous multimedia stream contents simultaneously. This paper focuses on introducing design concepts, operation details and on evaluating system performance and doing sensitivity analysis with respect to the change of the system components. The performance evaluation is performed using simulation in order to identify the system component that mostly affects the system performance. The sensitivity analysis shows the service delay rates of the multimedia stream server depending on the user's service request pattern. Also, the analysis is made on the utilization rates of the core system components such as the PCI bus and the Ethernet card, and on the system performance change by adding more system components.

• Journal of KIISE:Databases
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• v.27 no.2
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• pp.185-198
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• 2000

Recently the technological advance in the hardware dealing with multimedia data as well as the explosive increase of the volume of multimedia data bring about new interest in the use of multimedia presentations in many application domains. To use multimedia presentations efficiently, the integration of multimedia presentations into DBMS is necessary. This paper presents a multimedia presentatation query language based on contents and query processing techniques. Presently, multimedia presentation authoring tools denote a multimedia presentation using a presentation graph which is a DAG. A Node in the graph is a same type of media stream and edges denote a play-out order and a synchronization way among nodes. The contents of presentations graphs are the information of each stream, the sequential order of the information inside each stream and the play-out order among the streams. GCalculus/S is a calculus-based query language and can deal with the contents of a presentation graph and physical characteristics of multimedia data. It expresses the sequential order of information inside each stream and the play-out order of streams of a presentation graph using temporal operators Next, Connected and Until. O-Algebra, which is object algebra, is extended to process GCalculus/S queries.

• Journal of Ubiquitous Convergence Technology
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• v.2 no.2
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• pp.88-96
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• 2008

IPTV Content delivery systems over wired networks confront scalability problems due to their high network bandwidth requirement for real-time services. Especially, VoD service provides Trick Mode features such as pause, fast forward and similar operations. However, Trick Mode services are delivered by the method of unicast only for controlling of the stream. With a point of views, this paper propose a new real-time multimedia streaming architecture over IP Networks, which tries to achieve bandwidth efficiency and supporting for mass clients better than traditional unicast services. The proposed methods divide the Transport Stream into a series of segments. After that, this divided partial Transport Stream makes multicast streaming periodically. Meanwhile Set-top Box of a client makes a rearrangement orderly by using Presentation Time Stamp field from the served Transport Stream packets. While the current Transport Stream segment is playing, it should be guaranteed that the next segment is downloaded on time. Consequently, the original video content can be played out continuously. The detail introduction of a new real-time multimedia streaming system with analysis and simulation follows as below.

• Journal of Korea Multimedia Society
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• v.10 no.3
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• pp.401-410
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• 2007

Multimedia streams transmitted through the Internet have a strict playback delay time. Multimedia data arriving aster the playback time cannot be played in the receiver and are discarded. Thus, this paper proposed a protocol, in which the multimedia stream server determines whether data can be played in the receiver before sending the data. The proposed model has a PSCTP sub-layer on top of existing PR-SCTP and decides whether to send data messages, which have come from the multimedia applicationserver, and which PR-SCTP stream the data will be sent to. In addition, the proposed model uses the differentiated retransmission function of PR-SCTP. We evaluated the performance of SCTP, PR-SCTP and PSCTP using NS2 simulator. According to the results of the evaluation, the PSCTP protocol decreased the volume of transmission and increased the video decodable ratio compared to other protocols.

• Journal of Korea Multimedia Society
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• v.2 no.3
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• pp.277-288
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• 1999

A distributed multimedia school system is developed for the multimedia classroom at high school and university. The system is designed and implemented for students to improve the learning efficiency through the personalized multimedia contents and pace of learning. The previously developed multimedia information retrieval systems have some limitations on being applied to the multimedia classroom: expensive cost per stream or poor retrieval quality inappropriate for education, unscalability of system and service, unfamiliar proprietary client environment, and difficulty for teachers to use the authoring tools and manage the authored teaching materials. The system we developed overcomes the above problems. It is so scalable as to be applicable not only to a segmented classroom but also to the world wide Internet. The stream server is one of the components of the system: stream servers clients, a service gateway system, and a authoring management system. This paper describes the design and implementation of the stream server. A single stream server can simultaneously playback the multimedia streams as many as clients at one classroom. This is achieved only by the software engine without any changes of the hardware architecture. The systematic coupling with other components gives the scalability of the system and the flexibility of services.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.11a
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• pp.483-487
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• 2001

대용량의 MPEG 비디오 데이터를 시간적 개념의 layer coding 기법과 화질적 개념의 layer coding 기법을 통해서 나누는 방법을 통합하여 적용시킴으로써, 세분화되어진 layered steam을 얻을 수 있다. 그러나, 이러한 layered stream을 어떠한 정책을 사용하여 저장을 수행하는 것이 효율적인지에 대해서는 현재로서는 연구가 미흡한 편이다. 이에 layered stream의 관계를 이용하여 load-balance을 구성하는 각 요소의 상관 관계를 고려하여 병렬 VOD서버를 구성하는 각 노드마다 lead balancing을 이루도록 데이터를 저장하는 방법에 대해 제안하고자 한다.

• Proceedings of the IEEK Conference
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• 2000.06c
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• pp.141-144
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• 2000

Current Internet and Intranet developments are focusing on network multimedia services involving the transport of real-time multimedia streams. In this paper, we present a real-time MPEG2 Encoding/Decoding systems and a MPEG2 stream player running on client systems based on real-time transport protocol(RTP). The MPEG2 player has been implemented by using JMF and java applet. We have tested our prototype systems with one of possible multimedia sources, camcoder, to verify its functional correctness and measure its performance.

• The Journal of the Korea Contents Association
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• v.7 no.2
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• pp.100-108
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• 2007

Currently, multimedia stream services are provided in various network environments such as wireless networks. It is crucial to address QoS problem for multimedia service in heterogeneous networks. This paper suggests the scheme to increase the efficiency for the transmission of multimedia data. We also propose the adaptive algorithm that switch between UDP and TCP based on the size of the transmitted multimedia data. In addition, it presents the method that duplicates the multimedia data for the efficiency of transmission. We designed the MPEG stream service and conducted the simulation to verify our adaptive MPEG stream service.

• Journal of Korea Multimedia Society
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• v.4 no.4
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• pp.297-305
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• 2001

Recently advances in high-speed networks and multimedia computer technologies allow new types of multimedia applications to manipulate large volumes of multimedia data. However, in the real time and/or the heterogeneous data transmissions, there are many difficulties such as network transmission delay, the implementation difficulties, and so on. To solve these problems, in this paper, we extend the method of the multimedia service design which is proposed by OMG. To do this, we suggest an efficient real time audio/video stream framework, called Smart Explorer, based un CORBA and JMF Java Media API. And we separate the transmission path of control data from that of media data and use RTP/RTCP protocol for efficient real time audio/video transmission. Also we show the appropriate implementation of the audio/video stream system based on our suggested framework Smart Explorer. In the future, we expect our audio/video stream system to be applied to the real time communication software such as broadcasting, distance learning, and video conferencing.