• Proceedings of the Korea Information Processing Society Conference
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• 2001.10a
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• pp.247-250
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• 2001

멀티미디어 서버 시스템은 고용량이어야 하며 지속적으로 늘어나는 사용자수 뿐만 아니라 추가되는 새로운 저장 공간에 대한 우수한 확장성을 제공하여야 하는 것이 필수 불가결이다. 그러나 현재의 범용 서버 시스템은 이러한 요구사항을 충분히 반영하지 못할 뿐만 아니라 늘어나는 사용자 부하와 시스템 요구에 대한 고려, 그리고 미디어 데이터에 대한 반영이 이루어지지 못하여 점차 증가되는 사용자의 고화질 미디어 서비스 요구 사항을 충족시키지 못하고 있다. 본 논문에서는 구현된 시스템의 서비스 방식과 확장성 있는 구조가 고 대역폭 고화질 On-Demand 서버로서 효율적인 대안임을 보이며 또한 QoS 요구 보장과 효율적인 시스템 Management 정책을 제시하여 범용 서버를 멀티미디어 저장 및 Streaming 서버에 적합한 환경의 클러스터로 구성하는 방법을 제시한다.

• The KIPS Transactions:PartC
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• v.16C no.4
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• pp.487-494
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• 2009

VOD(Video On Demand) that provides streaming service according to the user's requirement in real time, consists of the video streaming server and the client system. Since it is very hard to apply the traditional server-client model that a server communicates with many clients through 1:1 connection to VOD system because it requires very high network bandwidth, many researches have been done to address this problem. Batching technique is one of VOD system based on Multicast that requires very small network bandwidth. However, the batching based VOD system has a limitation that it is very hard to provide VCR(Video Cassette Recorder) ability. In this paper, we propose a technique that reduces the required network bandwidth to provide VCR function by using the characteristic of MPEG, one of international video compression standard. In the proposed technique, a new video stream for VCR function is constructed with I pictures that is able to be decoded independently. The new video stream for VCR function is transmitted with the video stream for normal play together in Batching manner. The performance evaluation result shows that the proposed technique not only reduces the required network bandwidth and memory usage but also decreases the CPU usages.

• Journal of Information Processing Systems
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• v.14 no.5
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• pp.1272-1285
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• 2018

The paper presents a novel embedded multifunctional media sever (EMMS) for mobile devices to receive various media programs. Being different from other contemporary system research, the paper mainly studies how to design a reception solution for terrestrial digital television (DTV) on mobile devices and how to enable mobile devices can receive DTV program, enjoy video-on-demand (VOD), achieve video surveillance and relay Internet video program via local Wi-Fi simultaneously. In the system design, we integrate broadcasting-terrestrial DTV tuner, streaming media re-transmission system, VOD disk, video camera and access interface to the Internet into EMMS, which can either receive terrestrial DTV radio signals and demodulate out digital transport stream (TS), or can read streaming media bit-stream from VOD disk, surveillance camera or access interface to the Internet. The experimental results show the proposed system is stable and quality-efficient. Comparing with the other systems, the proposed system has the least packet loss rate and response time.

• The KIPS Transactions:PartA
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• v.8A no.4
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• pp.287-292
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• 2001

Multimedia service systems should have efficient capacity to serve the growing clients and new data. In the general streaming services, users can endure the small amount of time delay at the beginning of service. But they want to have good quality of service. A streaming server tries to transfer video files to clients from a repository of files in real time. The server must guarantee concurrent and uninterrupted delivery of each video stream requested from clients. To achieve its purpose, many stream servers adopt multi-processors, sufficient memory, and RAID or SAN in their systems. In this paper, we propose a Linux-based parallel media streaming server. It is superior to the other systems in the storing structure, fault-tolerance, and service capacity. Since this system supports the web interlace, users can operate easily through the www. This system uses unique striping policy to distribute multimedia files into the parallel storage nodes. If a service request occurs, each storage node transmits striped files concurrently to the client. Its performance is better than the single media streaming service because of the parallel architecture.

• Journal of Broadcast Engineering
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• v.24 no.7
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• pp.1209-1220
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• 2019

The demand for virtual reality (VR) is rapidly increasing. Providing the immersive experience requires much operation and many data to transmit. For example, a 360-degree video (360 video) with at least 4K resolution is needed to offer an immersive experience to users. Moreover, the MPEG-I group defined three degrees of freedom plus (3DoF+), and it requires the transmission of multiview 360 videos simultaneoulsy. This could be a burden for the VR streaming system. Accordingly, in this work, a bitrate-saving method using projection conversion is introduced, along with experimental results for streaming 3DoF+ 360 video. The results show that projection conversion of 360 video with 360lib shows a Bjontegaard delta bitrate gain of as much as 11.4%.

• IEMEK Journal of Embedded Systems and Applications
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• v.10 no.4
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• pp.241-255
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• 2015

Recent network environment has been rapidly evolved to cloud computing environment based on the development of the Internet technologies. Furthermore there is an increasing demand on mobile cloud computing due to explosive growth of smart devices and wide deployment of LTE-based cellular networks. Thus mobile Desktop-as-a-Service(DaaS) could be a pervasive service for nomadic users. In addition, video streaming traffic is currently more than two-thirds of mobile traffic and ever increasing. All such trends enable that video streaming in mobile DaaS could be an important concern for mobile cloud computing. It should be noted that the performance of the Transmission Control Protocol(TCP) on cloud host servers greatly affects Quality of Service(QoS) of video streams for mobile users. With widely deployed Linux server platforms for cloud computing, in this paper, we conduct an experimental analysis of the twelve Linux TCP variants in mobile DaaS environments. The results of our experiments show that the TCP Illinois outperforms the other TCP variants in terms of wide range of packet loss rate and propagation delay over LTE-based wireless links between cloud servers and mobile devices, even though TCP CUBIC is usually used in default in the current Linux systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.7B
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• pp.679-689
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• 2006

Delivering multicast stream is one of the cost-saving approach in the large scale VOD environment. Because implementing VCR-like interactions for user's convenience in the multicast streaming system involves complex problems, we need the proper solutions for them. In this paper, we propose a hybrid scheme which uses the general P2P and the patching scheme with the Collaborative Interaction Streaming Scheme(CISS). CISS provides jumping functionability to the appropriate multicast session after VCR-like interaction in the environment in which multiple peers transmit VCR-like interaction streams to the VCR-like functionability request node to reduce the loads generated by frequent join or departure of peers at the multicast tree during providing VCR-like functionability. Therefore, with the proposed scheme we can distribute network traffic and reduce control overhead and latency. And to evaluate the performance of proposed scheme we compare it in the aspect of the performance of streaming delivery topology, control overhead and streaming quality with P2Cast[10] and DSL[11]. The simulation result shows that proposed P2Patching reduces about 30% of process overhead and enhances about $25{\sim}30%$ of streaming quality compared with DSL.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.11a
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• pp.457-460
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• 2003

RTS(Real Time Streaming Protocol) 프로토콜은 어플리케이션 레벨에서 실시간 데이터 전송의 세션과 제어를 표현한다. 하지만, RTSP는 오든 스트리밍 솔루션에 대한 내용을 포함하고 있어 그 내용이 포괄적이고. 회사별 자신의 응용과 환경에 맞게 RTSP 표준을 구현하고 있어 상호호환이 어렵다. 본 논문에서는 주문형 미디어 시스템에 필요한 기본 기능을 RTSP 표준을 이용하여 어떻게 구현해야 하는지에 대한 방법을 제시함으로써, RTSP 지원 업체간의 호환성을 유도한다.

• Information and Communications Magazine
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• v.28 no.3
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• pp.19-26
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• 2011

본고에서는 스마트 TV의 대표적인 서비스인 OTT(Over-The-Top)서비스의 전송 방법 중 최근에 가장 주목을 받고 있는 HTTP에 기초한 적응적 스트리밍 기술을 알아본다. 먼저, 최근 MPEG등 각 표준단체에서 진행되고 있는 HTTP 스트리밍 기술의 표준화 범위 및 진행 상황에 대해서 살펴보고, 표준화 범위 중 핵심이 되는 메타데이타 파일 구조 및 청크 단위의 전송 포맷 및 기존 시스템 포맷의 확장 사항 등에 대해서 설명한다. 마지막으로 MPEG DASH(Dynamic adaptive streaming over HTTP)의 basic on-demand profile에 기초한 구현 내용 및 결과를 소개한다.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.182-182
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• 2004