• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.304-306
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• 2003

최근 이질적인 네트워크 환경에 적합한 다양한 멀티미디어 데이터를 서비스할 수 있는 연구가 광범위하게 이루어 지고 있다. 따라서 유동적인 네트웍 상황에 맞추어 전송되는 스트리밍 데이터는 사용자에게 보다 우수한 품질의 서비스를 제공받을 수 있는 기회를 준다. 본 논문에서는 대용량의 멀티미디어 데이터를 서비스하는 과정에서 발생하는 스트리밍 데이터의 에러 발생을 최소화할 수 있는 기법인 적응형 FEC 기법을 제안한다. 이 기법은 멀티미디어 데이터의 전송량을 최소화하면서 고화질 영상의 전송을 가능하게 한다.

• Journal of Broadcast Engineering
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• v.6 no.3
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• pp.246-259
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• 2001

Due to recent rapid deployment of Internet streaming service and digital broadcasting service, the issue of how to efficiently support streaming workload in so called "Internet Home Appliance" receives prime interests from industry as well as academia. The underlying dilemma is that it may not be feasible to put cutting edge CPU, boards, disks and other peripherals into that type of device. The primary reason is its cost. Usually, Internet Home Appliances has its dedicated usage, e.g. Internet Radio, and thus it does not require high-end CPU nor high-end Va subsystem. The same reasoning applies to I/O subsystem. In Internet Home Appliances dedicated to handle compressed moving picture, it is not equipped with high end SCSI disk with fast rotational speed. Thus, it is mandatory to devise elaborate software algorithm to exploit the available hardware resources and maximize the efficiency of the system. This paper presents our experiences in the design and implementation of a new multimedia file system which can efficiently deliver the required disk bandwidth for a periodic I/O workload. We have implemented the file system on the Linux operating system, and examined itsperformance under streaming I/O workload. The results of the study show that the proposed file system exhibits superior performance than the Linux Ext2 file system under streaming I/O workload. The result of this work not only contribute to advance the state f art file system technology for multimedia streaming but also put forth the software which is readily available and can be deployed. deployed.

• Journal of KIISE:Computing Practices and Letters
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• v.13 no.5
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• pp.260-270
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• 2007

Owing to the improved wireless communication technologies, it is possible to provide streaming service of multimedia with PDAs and mobile phones in addition to desktop PCs. Since mobile client devices have low computing power and low network bandwidth due to wireless network, the transcoding technology to adapt media for mobile client devices considering their characteristics is necessary. However, since mobile clients use wireless network and the wireless network have less stable bandwidth according to distance from AP and environments, it is hard to support stable QoS to mobile clients. In this paper, we propose a dynamic bit rate control method for transcoding in order to supprot stable QoS of streaming media service to mobile clients via wireless network. The proposed method is shown to serve seamless streaming media service with adaptive bit rate control according to state of wireless network in real time and to reduce transmission failure from experiment.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.05a
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• pp.909-912
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• 2008

무선 네트워크의 발달로 인해 이동 사용자가 급증함에 따라 무선 네트워크 환경에서도 질 높은 미디어 스트리밍 서비스를 받기 위한 수요가 증가하고 있다. 그러나 무선 네트워크는 유선 네트워크보다 상대적으로 좁은 네트워크 대역폭을 가진다. 또한 유선 네트워크 환경의 단말기에 비해 제한된 시스템 자원을 가지므로 유선 네트워크 환경의 사용자를 위한 고화질 미디어 데이터를 그대로 스트리밍 서비스 받기에 적합하지 않다. 최근 이러한 문제를 해결하기 위한 방법으로 미디어 트랜스코딩 서비스가 활발하게 연구되고 있다. 다수의 트랜스코딩 서버로 구성된 분산 트랜스코딩 시스템에서 특정 서버로 트랜스코딩 작업이 집중될 경우 사용자에게 질 높은 수준의 미디어 스트리밍 서비스를 제공하기 어렵다. 때문에 각 트랜스코딩 서버간의 균형적인 부하 분산이 중요한 문제가 되며, 처리되는 미디어 데이터의 특성을 부하 분산에 반영할 필요가 있다. 본 논문에서는 MPEG-2 미디어 데이터의 트랜스코딩 과정을 분석함으로써 비트율 변경에 따른 트랜스코딩 작업 시간 예측 기법을 제안한다. 제안된 기법은 트랜스코딩 서버 정보와 영화 정보, 목적 트랜스코딩 비트율을 이용하여 예상 트랜스코딩 시간을 예측한다.

• Korea Multimedia Society
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• v.16 no.3
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• pp.51-56
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• 2012

• Korea Multimedia Society
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• v.11 no.3
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• pp.57-69
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• 2007

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2001.05a
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• pp.271-288
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• 2001

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2001.11a
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• pp.407-420
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• 2001

• Journal of Korea Multimedia Society
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• v.12 no.7
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• pp.979-988
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• 2009

Illegal reproductions and subsequent copyright infringement have curtailed development of digital content industry. Many DRM systems have been developed and utilized for this purpose. However, current DRM system allow only authorized user to access the contents, and as such, redistribution to other user without getting license again entails cumbersome process. Currently, super-distribution system which can be used for redistribution of downloaded contents in more streamlined fashion is being widely conducted. But for streaming type content, it is still very difficult to redistribute with super-distribution system because the client must directly connect to streaming server to access the content. Accordingly, a new DRM streaming service structure is required to allow streamed contents to be redistributed as easily as the downloaded contents. In this paper, we proposed the relay file structure that can connect the streaming server and the user for super-distribution of the streaming contents.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.3
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• pp.254-265
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• 2003

This paper presents the design and implementation of stream control mechanisms which are necessary for the development of an efficient streaming cache server. The streaming protocols used in our implementation are the RTSP/RTP/RTCP standards. The mechanisms support both the on-demand media caching and real-time media splitting applications. The core of the stream control includes the session management, which handles the RTSP/RTCP control session and the RTP transport session, and the cache block management which efficiently manages the RTP-based cache blocks stored in the cache server. The streaming cache server with the proposed stream control mechanism has successfully been implemented on a Linux platform and it works well with the Apple's QTSS server and the QuickTime player for both on-demand and splitting media services.