• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.12C
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• pp.1055-1061
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• 2008

H.264 is the prominent video coding standard in various applications such as real-time streaming and digital multimedia broadcasting, since it provides enhanced compression performance, error resilience tools, and network adaptation. Compression efficiency of H.264 has been improved, however, it requires more computing and memory access than traditional methods. In this paper we proposed adaptive intra fast algorithm for real-time video surveillance system reducing the encoding complexity of H264/A VC. For this aim, temporal interrelationship between macroblock in the previous and the current frame is used to decide the encoding mode of macroblock fast. As a result, though video quality was deteriorated a little, less than 0.04dB, and bit rate was somewhat increased in suggested method, however, proposed method improved encoding time significantly and, in particular, encoding time of an image with little changes of neighboring background such as surveillance video was more shortened than traditional methods.

• Journal of Broadcast Engineering
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• v.16 no.6
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• pp.1073-1076
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• 2011

In this paper, we propose a scalable random access scheme in SVC based DASH service that enables random access support not only for base layer of SVC but also for enhancement layers. The proposed method includes extension of segment index box ('sidx') from DASH standard, as well as new RAP Synchronization Box ('raps'). Since the proposed scheme provides random access service for movie fragments with SVC encoded video layers, adaptive scalable random access service is possible.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2016.06a
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• pp.46-47
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• 2016

본 논문은 북미의 차세대 지상파 방송 표준인 ATSC 3.0에서 고려하고 있는 ROUTE(Real-time Object Delivery over Unidirectional Transport) 및 MPEG-DASH(Dynamic Adaptive Streaming over HTTP)를 기반으로 자유시점 방송 서비스를 송 수신하기 위한 SLS(Service Layer Signaling)을 제안한다. 특별히 ATSC 3.0과의 역호완성을 위하여 기존의 ROUTE/DASH의 SLS는 그대로 유지한 채 자유시점 방송을 위한 정보만 추가하여 기존의 SLS와 상호동작이 되도록 설계하였다. 따라서 본 논문에서 제안하는 내용은 향후 ATSC 3.0와 같이 IP(Internet Protocol)을 기반으로 SLS을 수행하는 표준규격과 역호환성을 유지한 채 자유시점 방송서비스를 할 수 있을 것으로 기대된다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.7
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• pp.1617-1625
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• 2010

Recently, the standardization of SVC technology which can provide adaptive video quality in diverse service environments has been completed. This paper proposes a layered encryption technique which takes into account the prioritized layer characteristics of SVC and control constant encryption complexity satisfying the target computational complexity. In particular, it analyzes the importance of NAL unit in the SVC video layer and suggests a method to apply appropriate encryption complexity proper for it. The effectiveness of the proposed method is proved through the comparison of time required for encryption and the reconstructed video quality using imperfect decryption key.

• Journal of KIISE
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• v.43 no.3
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• pp.327-335
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• 2016

In this paper, we propose a buffer management scheme suitable for interactive multimedia services. We consider a typical delay optimization environment so that receiver buffer lengths vary according to the round trip time estimation. In this environment, we propose an optimization technique for minimizing the loss of information that may occur when a reduced buffer length forces I/P/B frames in the buffer to drop. We modeled our problem as a Knapsack Problem for which we used dynamic programing in order to find an approximate solution. The proposed technique is compared with the existing buffer management techniques. Through simulation studies, we found that our approach could increase PSNR, which is important to video quality.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.216-219
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• 2011

DASH(Dynamic Adaptive Streaming over HTTP)는 MPEG(Moving Picture Experts Group)에서 표준화 중인 HTTP를 이용한 적응형 비디오 스트리밍 기술이다. 일반적으로 HTTP를 이용한 적응형 비디오 스트리밍에서 클라이언트가 사용할 수 있는 기능은 파일 전체 또는 그 일부를 다운로드하는 것이다. 따라서 전체 콘텐트를 작은 파일 조각 즉, 세그먼트(segment)로 분할하여 세그먼트들을 순차적으로 다운로드함으로써 마치 스트리밍이 달성되는 것과 같은 효과를 낼 수 있다. 네트워크의 상태에 따라 전송률을 조절하기 위해서는 서버에 서로 다른 비트율로 부호화된 세그먼트들을 함께 보관해 두어 클라이언트로 하여금 선택할 수 있게 한다. DASH에서는 MPEG-2 TS 또는 MPEG-4 파일 포맷(MP4)를 기반으로 하는 두 가지 형태의 서버 콘텐트를 제공할 수 있다. MP4 기반 DASH의 경우, 클라이언트가 수신한 세그먼트들을 순차적으로 이어 붙여 저장한다 하더라도 특별한 조건을 만족하는 경우를 제외하고는 MP4 파일을 재생할 수 있는 기존 미디어 플레이어가 이를 재생하지 못한다. 본 논문에서는 이러한 특별한 조건을 제시하고 이를 검증하였다. 이 조건은 서버에서 제공하는 세그먼트들에 대한 조건이다.

• Journal of Multimedia Information System
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• v.4 no.4
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• pp.179-188
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• 2017

The Internet Video Coding (IVC) standard is due to be published by Moving Picture Experts Group (MPEG) for various Internet applications such as internet broadcast streaming. IVC aims at three things fundamentally: 1) forming IVC patents under a free of charge license, 2) reaching comparable compression performance to AVC/H.264 constrained Baseline Profile (cBP), and 3) maintaining computational complexity for feasible implementation of real-time encoding and decoding. MPEG experts have worked diligently on the intellectual property rights issues for IVC, and they reported that IVC already achieved the second goal (compression performance) and even showed comparable performance to even AVC/H.264 High Profile (HP). For the complexity issue, however, there has not been thorough analysis on IVC decoder. In this paper, we analyze the IVC decoder in view of the time complexity by evaluating running time. Through the experimental results, IVC is 3.6 times and 3.1 times more complex than AVC/H.264 cBP under constrained set (CS) 1 and CS2, respectively. Compared to AVC/H.264 HP, IVC is 2.8 times and 2.9 times slower in decoding time under CS1 and CS2, respectively. The most critical tool to be improved for lightweight IVC decoder is motion compensation process containing a resolution-adaptive interpolation filtering process.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06d
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• pp.224-229
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• 2008

기존의 웹 서비스용 프록시는 숫자와 문자형, 이미지와 같은 크기가 비교적 작은 데이터 전송에는 성공 적인 방법이지만, 스트리밍 데이터의 특성으로 인하여 스트리밍 데이터 전송에는 적합하지 않다. 그래서 대안으로 CDN 같은 방법도 사용되고 있지만 새로운 인프라를 구성해야 하므로 엄청난 비용이 든다. 따라서 기존의 프록시 자원을 활용한 스트리밍 프록시 방법에 대한 많은 연구가 진행 중이다. 이러한 방법들은 스트리밍 데이터 전체를 캐싱하는 데는 많은 문제점들이 있기 때문에 컨텐츠를 보다 작은 단위로 나누어 캐싱하는 방법들이 제안되었다. 컨텐츠를 나누는 방법으로는 각 연구별 다른 기준으로 나누어지는데 본 논문에서는 이미 코딩이 되어 있는 신호를 다른 신호로 바꾸는 트랜스코딩에 프록시를 더해서 균등한 크기로 세그먼트를 나누는 방법의 단점인 데이터의 교체수가 너무 많은 점을 개선하기 위한 혼합 세그먼트 기반의 트랜스코딩 프록시를 제안하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2C
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• pp.139-147
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• 2006

This paper presents an overlay video multicast system over the Internet. The proposed system consists of two parts, i.e. overlay multicast tree suitable for the real-time video delivery and H.263+ rate control adaptive to overlay multicast tree. Overlay multicast tree is constructed to minimize the average time delay of members, and H.263+ rate control pursues a tradeoff between spatial and temporal qualities to enhance the human visual perceptual quality. Two systems are integrated and tested over the real Internet. And experimental results are provided to show the performance of the proposed system.

• Journal of Communications and Networks
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• v.6 no.3
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• pp.280-286
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• 2004

The widespread use of the Internet and the maturing of digital video technology have led to an increase in various streaming media application. However, new classes of hosts such as mobile devices are gaining popularity, while the transmission became more heterogeneous. Due to the characteristics of mobile networks such as low speed, high error bit rate, etc., the applications over the wireless channel have different needs and limitations from desktop computers. An intermediary between two communicating endpoints to hide the heterogeneous network links is thought as one of the best approaches. In this paper, we adopted the concept of inter-packet gap and the sequence number between continuously received packets as the error discriminator, and designed an adaptive packet sizing mechanism to improve the network efficiency under varying channel conditions. Based on the proposed mechanism, the packetization scheme with error protection is proposed to scalable encoded video delivery. Finally, simulation results reveal that our proposed mechanism can react to the varying BER conditions with better network efficiency and gain the obvious improvement to video quality for stored MPEG-4 FGS video delivery.