• 한국정보과학회:학술대회논문집
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• 한국정보과학회 1998년도 가을 학술발표논문집 Vol.25 No.2 (3)
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• pp.465-467
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• 1998

MPEG-2 는 Layered Coding방식을 채택하여 하나의 base layer와 4개의 enhancement layer로 이루어져 있으나 동영상 재생을 위해 필요한 최소한의 layer인 base layer 만으로도 데이터 양이 많기 때문에 인터넷 환경에 적용하기가 어렵다. 이에 base layer를 다시 세분화된 layer로 나누기 위해 인코딩 중에는 또는 인코딩 결과로 만들어지는 MPEG-2 Video steam 의 하부 구조인 블록층에 존재하는 8$\times$8블록의 AC 계수들을 layering한다. Layered된 base layer의 데이터는 통신망 및 단말기의 QoS에 따라 서로 다른 전송 채널을 통해 서버에서 클라이언트 디코더로 전송된 후 디코더에 실시간적으로 병합한 후 재생된다. 본 논문에서 제안하는 기법을 이용하여 기존에 encoding MPEG-2 Video steam의 AC계수를 layering할 경우에 QoS에 따라 가변적으로 데이터 양을 서버 쪽에서 조절할 수 있었고, 통신 선로 상에서 이동하는 데이터 양의 원래의 MPEG-2 Video steam 을 이용했을 때보다 인코딩 중에 블록을 변환하면 51% 정도 감소하고 인코딩 되어진 데이터를 이용했을 경우에는25%정도 감소하는 것을 알 수 있었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(4)
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• pp.203-206
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• 2001

This Paper suggests real-time video streaming method by using DCT-based scalability, and evaluates and analyzes the function. It is similar to using lowpass filter. That is, as following figure, this method is to split the encoded data in splitter and transmit it, and to decode the data according to the situation. This method can be applied to any video CODEC which is based on DCT. Therefore, this thesis suggests easy video streaming method by using DCT-based scalability, and shows the result of experiment. By using suggested scalability, calculations are reduced, and spacial scalability is realized. Moreover, the objective data which meet user's need according to the network condition and choose the appropriate scalability according to the capability of terming can be extracted. And it is possible to apply any resources according to the specificity of image.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.855-858
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• 1998

Nowadays it is possible to make realization of Multimedia service by virtue of developing computer hardware technique and high-bandwidth network. But Multimedia service has some problems. Its file need large storage. Above all, Analog CCTV used in recent has been utilized for various purpose in ban, company and public institution, but this has many defects such as management, low resolution, and etc. To overcome this problems, multimedia component-file-have to be reduced in size. This paper proposes adaptive MPEG-1 video to reduce file size. The method in this paper is realized that according to movement variation, file size is reduced by adaptively making use of MQuant.

• 한국정보과학회논문지:컴퓨팅의 실제 및 레터
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• 제10권3호
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• pp.243-250
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• 2004

본 논문은 실용화 레벨에서의 디지털 영상기록 (Digital Video Recording: DVR) 구현을 기술한다. 또한 입력 영상을 배경과 목표물 영역의 두 가지 영역으로 분리 처리하여 분리된 영역별로 중요도를 고려하여 서로 다른 압축 기법을 적용함으로써 효율적인 압축부호화를 수행할 수 있는 방안을 제안한다. 본 알고리즘은 영상 압축 부호화 기법으로서 영역분할을 통해 Macro block 단위로 물체 영역과 배경 영역을 재구성해서 부호화에 이용하는 방식이다. 제안된 알고리즘은 매우 효율적인 압축 성능을 보여주며, 저 전송률 상황에서도 높은 질의 영상을 복원할 수 있다.

• Journal of Communications and Networks
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• 제7권3호
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• pp.235-242
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• 2005

Multimedia applications and especially encoded video services, are expected to playa major role in the 3rd generation (3G) and beyond mobile communication systems. Given that future service providers are expected to provide video applications at various price and quality levels, quick and economically affordable methods for preparing/encoding the offering media at various qualities are necessary to be developed. This paper presents a method for objective evaluation of the perceived quality of MPEG­4 video content, based on a quantification of subjective assessments. Showing that subjectively derived perceived quality of service (PQoS) vs. bit rate curves can be successfully approximated by a group of exponential functions, the proposed method exploits a simple objective metric, which is obtained from the mean frame rate vs. bit rate curves of an encoded clip. The validity of this metric is assessed by comparing subjectively derived PQoS results to the corresponding ones, which come from the proposed objective method, showing that the proposed technique provides satisfactory PQoS estimation.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 Ⅳ
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• pp.2040-2043
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• 2003

General-purpose MPEG-2 video transcoders must be able to achieve any conversion between 18 ATSC (Advanced television system committee) video formats for DTV (digital television), e.g., scan format, size format, and frame rate format conversion. Especially, scan format conversion is hard to implement because frame rate and size format conversion often happen together. This paper proposes a fast motion estimation(ME) algorithm for MPEG-2 video transcoding supporting scan format conversion. Firstly, we extract and compose a set of candidate motion vectors (MV's) from the input bit-stream to comply with the re-encoding format. Secondly, the best MV is chosen among several candidate MV's by using a weighted median selector. Simulation results show that the proposed ME algorithm reduces significantly transcoding complexity with a minor PSNR degradation.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.207-210
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• 2009

An efficient algorithm to compress high dynamic range (HDR) videos is proposed in this work. We separate an HDR video sequence into a tone-mapped low dynamic range (LDR) sequence and a ratio sequence. Then, we encode those two sequences using the standard H.264/AVC codec. During the encoding, we allocate a limited amount of bit budget to the LDR sequence and the ratio sequence adaptively to maximize the qualities of both the LDR and HDR sequences. While a conventional LDR decoder uses only the LDR stream, an HDR decoder can reconstruct the HDR video using the LDR stream and the ratio stream. Simulation results demonstrate that the proposed algorithm provides higher performance than the conventional methods.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2005년도 추계학술발표대회 및 정기총회
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• pp.151-154
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• 2005

본 논문에서는 스케일러블 멀티미디어 콘텐츠에 대한 조건적 접근제어가 가능한 암호화 방법을 제안한다. 현재 표준화가 진행중인 스케일러블 비디오 코딩방법인 JSVM(Joint Scalable Video Model)은 부호화한 동영상에 대해 공간, 시간, 품질의 스케일러빌리티(Scalability)를 지원하는데, 각 스케일러 빌리티를 고려한 조건적인 접근제어기술은 스케일러빌리티에 따라 사용자를 제한해야 하는 경우를 위해 필수적인 기술이다. 제안하는 방법은 공간, 시간, 품질의 세가지 스케일러빌리티를 지원하도록 부호화(Encoding)후 구성되는 NAL(Network Abstract Layer)을 지원하는 스케일러빌리티에 따라 구분하고, 구분된 NAL 의 종류에 따라 암호화 key 를 다르게 제공하는 방법을 통해 사용자의 접근제어 수준에 맞게 암호화 key 를 조합하는 방법을 적용하였다. 실험 결과 제안한 방법은 JSVM 에서 공간, 시간, 품질의 스케일러빌리티가 보장되고, 이때 생성되는 Key 의 조합으로 조건적 접근제어(Conditional access control)가 가능함을 확인하였다.

• 한국군사과학기술학회지
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• 제23권1호
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• pp.28-36
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• 2020

Due to the continued demand for high-definition video, video compression technology is steadily developing and the High Efficiency Video Coding standard was established in 2013. However, despite the development of this compression technology, it is very difficult to smoothly transmit VGA-level videos in Ultra-narrowband environments. In this paper, the target information preprocessing algorithm is presented for smooth transmission of target images moving in forest or open-terrain in Ultra-narrowband environment. In addition, for algorithm verification, the target information preprocessing algorithm was simulated and the simulated results were compared with the video compression result without the algorithm being applied.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권8호
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• pp.3121-3135
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• 2015

Owing to the increase in consumption of multimedia content and the improvement of device capacity, user demand for high-quality content has increased. However, it is difficult to transport such large amounts of content over the existing broadcasting network with limited bandwidth. To provide high-definition broadcasting, some studies suggest methods of transporting multimedia over heterogeneous networks after encoding content hierarchically. MPEG Media Transport (MMT), standardized by Moving Picture Experts Group (MPEG), is a solution that enables large-volume media transport over heterogeneous networks such as digital broadcasting networks and packet-switched networks. In the case of delivering a scalable encoded video over different networks, synchronization of each stream is an important issue. MMT defines a synchronization scheme, but does not contain sufficient functions to implement it. In this paper, we propose a synchronization scheme for media streams that are encoded hierarchically, divided into layers, and transported over heterogeneous networks. We implement our scheme using MMT and HTTP, and experimented using three encapsulated video streams with different durations. As a result, we show that the proposed scheme can reduce the waiting time to display high-quality video, relative to Dynamic Adaptive Streaming over HTTP-Scalable Video Coding (DASH-SVC) by requesting segments of enhanced layers after calculating the transmission time. Additionally, we find out that the selection of durations have a relation to the characteristics of the video.