• Journal of KIISE
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• v.44 no.5
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• pp.545-552
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• 2017

Because of the explosive growth of mobile devices and development of network technologies, HTTP (Hypertext Transfer Protocol) adaptive streaming has become a new trend in video delivery to provide efficient multimedia streaming services. As interest in personalized broadcasting grows, the study of interactive multimedia has been actively pursued. The interactive multimedia service is a method of playing media according to a scenario selected by the user. Providing the interactive multimedia service with the existing HTTP adaptive streaming causes switching delay and buffer underflow according to the point in time when the user selects the scenario while the client streams the interactive multimedia and therefore decreases the user QoE (Quality of Experience). In this paper, we propose an adaptive streaming scheme for interactive multimedia service in HTTP adaptive streaming to provide seamless playback. We design the architecture and prefetching scheme for interactive multimedia streaming.

• Journal of Broadcast Engineering
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• v.23 no.4
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• pp.549-558
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• 2018

We designed and implemented streaming server based on MEPG DASH, which is able to provide high quality video with low-latency live streaming service like 360 VR video on the existing cable network via low-spec media service devices such as IPTV and OTT(Over the Top) SettopBox. We also designed and applied management process which is cable of supporting services by cashing streaming video file(MPD, Segment Files) to reduce the server response delay time. Further more, we confimred that it is also able to provide high quality of tiled video streaming with over 50,000kbps bitrate and 8K@60P through the experiment.

• Journal of Broadcast Engineering
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• v.17 no.4
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• pp.584-595
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• 2012

Recently, 3D stereoscopic video and HTTP adaptive streaming technologies have received a lot of attention from relevant industrial fields and markets in terms of multimedia contents and delivery services, respectively. It is expected that promising and marketable service models can be created by means of these noticeable two technologies. However, current standard specifications do not provide a method for organized connection between those two technologies. 3D stereoscopic video services are weighted in broadcasting and storage services that are only available under environments in which the network bandwidth is guaranteed or free. Also, HTTP adaptive streaming technologies only provide plain 3D service methods that are dependent on particular Codec. Therefore, this paper proposes 3D video delivery format for HTTP adaptive streaming service which enables stable and seamless display for various stereoscopic video sequences over internet networks. The proposed technology is designed on the basis of Stereoscopic Video Application Format which is a service-oriented standard specification for storing stereoscopic video sequences. Also, this delivery format is directly applicable over DASH that is the representative standard technology for HTTP adaptive streaming services. The delivery format proposed in this paper has been submitted to MPEG and it has been accepted as a working draft, thus it expected to pave the way for practical industrialization in relevant fields from now on.

• Journal of the Korea Society of Computer and Information
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• v.17 no.6
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• pp.145-152
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• 2012

Due to the large sizes of streaming media, previous delivery techniques are not providing optimal performance. For this purpose, video proxy server is employed for reducing the bandwidth consumption, network congestion, and network traffic. This paper proposes a fast distributed network file system using state transition model in the media streaming system for efficient utilization of video proxy server. The proposed method is composed of three steps: step 1. Training process using state transition model, step 2. base and decision probability generation, and step 3. storing and deletion based on probability. In addition, storage space of video proxy server is divided into each segment area in order to store the segments efficiently and to avoid the fragmentation. The simulation results show that the proposed method performs better than other methods in terms of hit rate and number of deletion. Therefore, the proposed method provides the lowest user start-up latency and the highest bandwidth saving significantly.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12B
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• pp.735-742
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• 2007

We propose an effective packet marking algorithm for video streaming in DiffServ network. Because legacy packet markers such as srTCM(single rate three color marker) cannot distinguish the importance of packet, these markers can cause quality degradation of streaming during the network congestion period. Recently proposed TMS (Two Marker System) [4] shows effectiveness in such scenario that video streaming service is struggling with other types of service traffic. However, if many video streaming services co-exist in DiffServ network and result in competition among themselves, then both legacy packet markers and even TMS cannot prevent drastic streaming quality degradation. To cope with this, we suggest A-TCPM (Adaptive time sliding window Three Color Marker) algorithm. In this algorithm, an A-TCPM module decides the color of a racket based upon the probability which is lead by current channel status and frame importance ratio. Simulation results show that proposed A-TCPM algorithm can enhance streaming service quality especially when overbooked video streaming sessions struggle with themselves.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.8B
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• pp.751-759
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• 2009

Due to the advance of WLAN technology, the use of the multimedia service such as the video streaming service has been increased in the home network. However, we need to study the method which decreases the transmission delay and the frame loss rate to provide QoS of the video streaming service. Therefore, this paper proposes an active buffer management mechanism to guarantee QoS of the streaming service in IEEE 802.11e EDCA. The proposed protocol discards the frame in the HoL of the buffer based on the importance of each frame and the virtual transmission delay of frame newly arriving at the buffer. In the simulation results, the proposed algorithm not only decreases the frame loss probability of important I and P frames but also stabilizes the transmission delay. It may increase the QoS of video streaming services.

• Journal of KIISE:Computing Practices and Letters
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• v.8 no.3
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• pp.318-327
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• 2002

This paper Introduces a new scanning method for network-adaptive scalable streaming video coding methodologies such as the MPEG-4 Fine Granular Scalable (FGS) Coding. Proposed scanning method can guarantee the subjectively improved picture quality of the region of the interest in the decoded video by managing the image information of that interested region to be encoded and transmitted most-preferentially, and also to be decoded most-preferentially. Proposed scanning method can lead the FGS coding method to achieve improved picture quality, in about 1dB ~ 3dB better, especially on the region of interest.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.334-336
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• 2012

비디오 스트리밍 서비스의 품질을 보장하기 위한 연구가 활발히 진행되고 있다. 그러나 기존 연구들은 모바일 단말의 이동에 따른 무선 채널 상태 변화에 대한 고려가 부족하다. 본 논문에서는 비디오 품질을 향상시키기 위하여, 새로운 비디오 전송 기법을 제안한다. 제안한 기법은 모바일 단말의 이동에 따른 무선 네트워크 상태 변화와 네트워크 혼잡상태를 고려하여 비디오 전송률을 조절한다. 시뮬레이션 결과를 통해 제안한 기법의 성능을 확인하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2019.11a
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• pp.230-232
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• 2019

최근 360 미디어 콘텐츠의 수요가 높아지면서 360 영상을 효율적으로 전송하기 위한 다양한 압축 및 전송 기법들이 연구되고 있다. 360 영상의 스트리밍 기법 중 하나인 타일 기반 적응적 스트리밍 기법은 360 비디오를 타일 그리드로 나누어 부호화 하고, 뷰포트(Viewport)에 해당하는 타일만 스트리밍 할 수 있도록 한다. 기존의 타일 기반 스트리밍 기법은 뷰포트가 전환될 때 서버에 새로운 인트라 프레임을 요구하고, 지연 시간을 줄이기 위해 빈번한 RAP(Random Access Point)가 요구된다는 단점이 있다. 본 논문은 기존의 타일 기반 스트리밍 방법에서 인트라 프레임의 공유를 통해 비트율의 효율을 높이는 IFS(Intra Frame Sharing) 알고리즘을 제안한다. 제안된 IFS 방법은 낮은 화질의 인트라 프레임을 높은 화질의 인트라 프레임 부호화 시 공유하여, 뷰포트 스위칭 시점에서 다른 화질 간의 뷰포트 전환 작업이 필요 없어 비트율의 증가를 최소화한다. 실험에서, IFS 방법은 기존의 MCTS 기반의 적응적 스트리밍 방식과 비교했을 때 BD-rate(%)가 약 13% 절감되었다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.99-101
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• 2011

MPEG-DASH(Dynamic Adaptive Streaming over HTTP)는 MPEG(Moving Picture Experts Group)에서 표준화 중인 HTTP를 이용한 적응형 비디오 스트리밍 기술이다. MPEG-DASH는 인터넷 방화벽에 의해 차단되는 RTP/UDP를 이용한 AV 스트리밍 대신 현재 HTTP/TCP를 이용하여 AV 스트리밍을 하는 추세에 맞춰 유무선 인터넷에서 망 환경 및 단말 환경에 동적 적응적으로 AV 스트리밍을 달성하기 위한 기술에 대한 표준이다. HTTP를 이용한 AV 스트리밍은 서버의 부담을 최소화하고 클라이언트의 지능적 처리에 전적으로 의존하는 스트리밍 방식이다. MPEG-DASH 클라이언트는 HTTP의 파일 전송 요청 또는 파일 일부 전송 요청만을 사용하여 스트리밍을 달성한다. 2011년 7월 제97차 MPEG 회의에서 MPEG-DASH DIS(Draft International Standard) 2차 버전이 승인되었다. 본 논문에서는 이 DIS 2차 버전에 따라 MP4 파일 포맷 기반의 MPEG-DASH 클라이언트를 구현하고 그 동작을 실험을 통해 검증하였다.