• 한국정보통신학회논문지
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• 제16권11호
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• pp.2465-2473
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• 2012

최근에 연구되어 온 초경량 비디오 부호화 기법으로 분산 비디오 부호화 기법에 대한 연구가 활발히 진행되고 있다. 우수한 부호화 효율을 얻기 위해 분산 비디오 부호화 기법은 패리티 비트 제어용으로 피드백 채널을 필요로 하고 있다. 그러나 이 방법은 매우 높은 복호화 지연을 야기하여 실시간 구현과 상용화에 극복해야 할 문제가 되고 있다. 이를 위해, 본 논문에서는 복호화기에서 보조정보를 생성할 때 생성되는 움직임 벡터를 부호화기측으로 전송하는 환경을 위한 고속 분산 비디오 복호화기법을 제안한다. 제안한 방법은 수신된 움직임벡터를 이용하여 비트-에러율을 계산하고, 이를 이용하여 복호화기측에서 전송함으로써 복호화 속도를 개선하는 방법을 사용한다. 모의실험을 통하여, 제안 방식은 기존에 제안된 기법에 비해 성능을 크게 개선시킬 수 있음을 보인다.

• JSTS:Journal of Semiconductor Technology and Science
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• 제13권5호
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• pp.430-442
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• 2013

This paper presents a fast multi-reference frame integer motion estimator for H.264/AVC. The proposed system uses the previously proposed fast multi-reference frame algorithm. The previously proposed algorithm executes a full search area motion estimation in reference frames 0 and 1. After that, the search areas of motion estimation in reference frames 2, 3 and 4 are minimized by a linear relationship between the motion vector and the distances from the current frame to the reference frames. For hardware implementation, the modified algorithm optimizes the search area, reduces the overlapping search area and modifies a division equation. Because the search area is reduced, the amount of computation is reduced by 58.7%. In experimental results, the modified algorithm shows an increase of bit-rate in 0.36% when compared with the five reference frame standard. The pipeline structure and the memory controller are also adopted for real-time video encoding. The proposed system is implemented using 0.13 um CMOS technology, and the gate count is 1089K with 6.50 KB of internal SRAM. It can encode a Full HD video ($1920{\times}1080P@30Hz$) in real-time at a 135 MHz clock speed with 5 reference frames.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권7호
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• pp.2464-2479
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• 2014

Multi-view video coding is an international encoding standard that attains good performance by fully utilizing temporal and inter-view correlations. However, it suffers from high computational complexity. This paper presents a fast encoder design to reduce the level of complexity. First, when the temporal correlation of a group of pictures is sufficiently strong, macroblock-based inter-view prediction is not employed for the non-anchor pictures of B-views. Second, when the disparity between two adjacent views is above some threshold, frame-based inter-view prediction is disabled. Third, inter-view prediction is not performed on boundary macroblocks in the auxiliary views, because the references for these blocks may not exist in neighboring views. Fourth, finer partitions of inter-view prediction are cancelled for macroblocks in static image areas. Finally, when estimating the disparity of a macroblock, the search range is adjusted according to the mode size distribution of the neighboring view. Compared with reference software, these techniques produce an average time reduction of 83.65%, while the bit-rate increase and peak signal-to-noise ratio loss are less than 0.54% and 0.05dB, respectively.

• 대한임베디드공학회논문지
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• 제9권2호
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• pp.81-86
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• 2014

In the scalable video coding standard, inter-layer prediction based on the coding information of the base layer was adopted to increase the coding performance. This prediction tool results in new syntax elements called motion_prediction_flag (mPF) and residul_prediction_flag(rPF), which are carried to notify the motion vector predictor (MVP) and reference block required in the motion compensation of the decoder. In this paper, an efficient coding method for mPF is proposed to enhance coding efficiency of the salable video coding standard. Through an analysis on the transmission of mPF based on the relationship between the MVPs, we discover the conditions where mPF is unnecessary at the decoder and suggest a modified rate-distortion (RD) cost function to make RD optimization more effective. Simulation results show that the proposed method offers BD rate savings of approximately 1.4%, compared with the conventional SVC standard.

• 한국멀티미디어학회논문지
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• 제8권9호
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• pp.1216-1226
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• 2005

본 논문에서는 동적 대역 할당이 가능한 네트워크에서 라이브 비디오의 고화질 전송을 위한 예방형 전송률 결정 방식을 제안한다. 부호기 앞단의 화면 분석기에서 입력 화면의 분산과 장면전환 정도로부터 향후 화면의 비트율을 예측하고, 부호기와 복호기 버퍼의 제약조건에 의한 전송률 범위를 구한다. 이를 토대로 빈번한 전송률 재협상에 따른 비용 증가 문제를 해결하기 위해 최근 재협상 시점으로부터 경과 시간, 비디오 수신 품질 등을 고려한 예방형 전송률 결정 방식을 제안한다. 모의실험을 통해 제안 방식은 정규화된 Least Mean Square 기반 전송률 결정 방식과 비교되었고, 적은 재협상 비용으로도 지연 위반 화면 없이 높은 채널 이용률 달성이 가능함을 보였다.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.351-354
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• 2009

Distributed video coding (DVC) is a new coding paradigm that enables to exploit the statistics among sources only in decoder and to achieve extremely low complex video encoding without any loss of coding efficiency. Wyner-Ziv coding, a particular implementation of DVC, reconstructs video by correcting noise on side information using channel code. Since a good quality of side information brings less noise to be removed by the channel code, generation of good side information is very important for the overall coding efficiency. However, if there are complex motions among frames, it is very hard to generate a good quality of side information without any information of original frame. In this paper, we propose a method to enhance the quality of the side information using small amount of additional information of original frame in the form of hash. By decoder's informing encoder where the hash has to be transmitted, side information can be improved enormously with only small amount of hash data. Therefore, the proposed method gains considerable coding efficiency. Results of our experiment have verified average PSNR gain up to 1 dB, when compared to the well-known DVC codec, known as DISCOVER codec.

• 방송공학회논문지
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• 제22권2호
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• pp.240-252
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• 2017

기존의 High Efficiency Video Coding(HEVC)기반의 다시점 비디오 부호화 기법은 종속 시점의 픽쳐를 부호화 할 때, disparity compensation prediction(DCP)을 위해 추가적인 참조 영상을 사용하기 때문에 높은 부호화 복잡도를 가지고 있다. 본 논문에서는 MV-HEVC에서 변위 움직임 벡터 탐색 복잡도를 줄이기 위한 빠른 변위 움직임 벡터 탐색 방법을 제안한다. 제안하는 방법은 어파인 변환을 이용한 초기 탐색 지점 결정 방법과 적응적인 탐색 영역 크기 결정 방법을 포함한다. 실험 결과는 제안하는 방법이 부호화 효율의 저하가 거의 없이 변위 움직임 탐색 복잡도를 90.78%까지 줄일 수 있는 것을 보여준다. 또한, 실험 결과는 제안하는 방법이 다른 복잡도 감소 기술들 보다 효과적으로 복잡도를 줄이는 것을 보여준다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권10호
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• pp.5013-5034
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• 2019

In the Peer-to-Peer (P2P) streaming systems, peers randomly form a network overlay to share video resources with a data scheduling scheme. A data scheduling scheme can have a great impact on system performance, which should achieve two optimal objectives at the same time ideally. The two optimization objectives are to improve the perceived video quality and maximize the network throughput, respectively. Maximizing network throughput means improving the utilization of peer's upload bandwidth. However, maximizing network throughput will result in a reduction in the perceived video quality, and vice versa. Therefore, to achieve the above two objects simultaneously, we proposed a new data scheduling scheme based on multi-objective particle swarm optimization data scheduling scheme, called MOPSO-DS scheme. To design the MOPSO-DS scheme, we first formulated the data scheduling optimization problem as a multi-objective optimization problem. Then, a multi-objective particle swarm optimization algorithm is proposed by encoding the neighbors of peers as the position vector of the particles. Through extensive simulations, we demonstrated the MOPSO-DS scheme could improve the system performance effectively.

• 방송공학회논문지
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• 제22권3호
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• pp.405-408
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• 2017

다시점 이미지의 뷰포인트 간에 높은 유사도가 존재함을 바탕으로 MV-HEVC는 뷰포인트 내에서 전통적인 시간적 방향 예측 뿐만 아니라 뷰포인트 간에 예측을 수행함으로써 높은 부호화 효율을 얻는다. 본 논문에서는 HEVC를 기본 계층으로 사용하는 스케일러블다시점 비디오 부호화를 구현하기 위해 SHVC와 MVC를 통합 구현함을 제안한다. 실험결과에 의해 BD-PSNR 개선이 1.5dB에 이르고 동시에 BD-Bitrate를 50~60% 가량 줄일 수 있음을 확인하였다.

• 제어로봇시스템학회논문지
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• 제11권5호
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• pp.471-475
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• 2005

Recently, development of digital technology is occupying a large part of multimedia information like character, voice, image, video, etc. Research about video indexing and retrieval progresses especially in research relative to video. This paper proposes the novel notation in order to retrieve MPEG video in the international standards of moving picture encoding For realizing the retrieval-system, we detect DCT DC coefficient, and then we obtain shot to apply MVC(Mean Value Comparative) notation to image constructed DC coefficient. We choose the key frame for start-frame of a shot, and we have the codebook index generating it using feature of DC image and applying PCA(principal Component Analysis) to the key frame. Also, we realize the retrieval-system through similarity after indexing. We could reduce error detection due to distinguish shot from conventional shot detection algorithm. In the mean time, speed of indexing is faster by PCA due to perform it in the compressed domain, and it has an advantage which is to generate codebook due to use statistical features. Finally, we could realize efficient retrieval-system using MVC and PCA to shot detection and indexing which is important step of retrieval-system, and we using retrieval-system over the internet.