• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.196-198
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• 2011

MPEG 과 VCEG 의 공동협력팀인 JCT-VC(Joint Collaboration Team on Video Coding)에서는 H.264/AVC 보다 두 배 이상의 높은 부호화 효율을 목표로 HEVC(High Efficiency Video Coding) 표준화를 진행하고 있다. HEVC 표준화에서는 압축 효율뿐만 아니라 부호화기의 복잡도도 중요하게 고려되고 있다. 본 논문에서는 HEVC 부호화기의 높은 복잡도를 줄이기 위하여 상위 깊이의 부호화 단위(Coding Unit: CU)의 움직임 정보를 이용하여 현재 부호화하는 예측단위(Prediction Unit: PU)의 참조영상의 후보의 수를 제한하는 고속 부호화 알고리즘을 제안한다. 모의실험을 통하여 제안한 알고리즘은 HM3.0 에 비해 평균 10.8% 정도의 부호화 시간을 감소시키며, 이때 평균 비트율은 0.5%로 부호화 효율의 감소가 미미함을 확인 하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.07a
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• pp.425-427
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• 2012

H.264/AVC 는 움직임 예측/보상을 수행할 때, 하나 이상의 다중 참조영상을 허용하여 예측 정확성을 높임으로써 높은 압축효율을 얻을 수 있지만, 부호화기가 높은 복잡도를 갖는 단점이 있다. 본 논문에서는 H.264/AVC 부호화기의 높은 복잡도를 줄이기 위하여 이미 부호화된 주변 블록의 부호화 정보와 현재 부호화하는 매크로블록(MB)의 $16{\times}16$ 화면간 예측 결과를 적응적으로 이용하여 현재 부호화하는 매크로블록의 참조영상 후보의 수를 줄이는 고속 부호화 알고리즘을 제안한다. 모의실험을 통하여 제안한 알고리즘은 JM17.2 에 비해 평균 47% 정도의 부호화 시간을 감소시키며, 이때 평균 비트율은 1.4%로 부호화 효율의 감소가 미미함을 확인 하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2015.11a
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• pp.141-142
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• 2015

본 논문에서는 HEVC(High Efficiency Video Coding)을 위한 고속 부호화 알고리즘을 제안한다. 제안 방법은 HEVC 의 화면내 부호화 과정에서 주변 부호화 모드 정보인 MPM(Most Probable Mode)과 RMD(Rough Mode Decision) 과정의 결과로 얻어지는 후보 모드들의 상관관계를 이용하여 높은 계산 복잡도를 가지는 RDO(Rate-Distortion Optimization) 과정이 고려하는 후보의 개수를 줄여 전체 부호화기의 부호화 복잡도를 낮춘다. 실험 결과에서는 제안 방법이 약 0.29% BD-rate 의 부호화 손실만으로 20.43%의 부호화 복잡도를 감소시켰음을 보인다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.3
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• pp.88-96
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• 2007

H.264 is a new international video coding standard that can achieve considerably higher coding efficiency than conventional standards. Its coding gain has been achieved by employing advanced video coding methods. Specially, the increased number of macroblock modes and the complex mode decision procedure using the Lagrangian optimization are the main factors for increasing coding efficiency. Although H.264 obtains improved coding efficiency, it is difficult to do an real-time encoding because it considers all coding parameters in the mode decision procedure. In this paper, we propose a fast mode decision algorithm which classifies the macroblock modes in order to determine the optimal mode having low complexity quickly. Simulation results show that the proposed algorithm can reduce the encoding time by 34.95% on average without significant PSNR degradation or bit-rate increment. In addition, in order to show the validity of simulation results, we set up a low boundary condition for coding efficiency and complexity and show that the proposed algorithm satisfies the low boundary condition.

• Journal of Korea Multimedia Society
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• v.14 no.7
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• pp.849-857
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• 2011

Gaming on demand(GOD) makes people enjoy games by encoding and transmitting game screen at a server side, and decoding the video at a client side. In this paper, we propose a fast game video encoder for multiple users over network with low-powered devices. In the proposed system, the computational complexity of game encoders is reduced by using scene descriptors, which consists of an object motion vector, global motion, and scene change. With additional information from game engines, the proposed encoder does not need to perform various complexity processes such as motion estimation and ratedistortion optimization. The motion estimation and rate-distortion optimization skipped by scene descriptors. We found that the proposed method improved 192 % in terms of FPS, compared with x264 software. With partial assembly code, we also improved coding speed by 86 % in terms of FPS. We found that the proposed fast encoder could encode over 60 FPS for real-time GOD applications.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.40 no.4
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• pp.275-285
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• 2003

The now video coding standard H.264 employs variable block size motion compensation, multiple references, and quarter-pel motion vector accuracy. These techniques are key features to accomplish higher coding gain, however, at the same time main factors that increase overall computational complexity. Therefore, in order to apply H.264 to many applications, key techniques are requested to improve their speed. For this reason, we propose a fast motion estimation which is suited for variable block size motion communication. In addition, we propose a fast mode decision method to choose the best mode at early stage. Experimental results show the reduction of the number of SAT SATD calculations by a factor of 4.5 and 2.6 times respectively, when we compare the proposed fast motion estimation and the conventional MVFAS $T^{［8-10］}$. Besides, the number of RDcost computations is reduced by about 45%. Therefore, the proposed methods reduces significantly its computational complexity without noticeable coding loss.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2014.06a
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• pp.268-270
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• 2014

본 논문은 FME (Fractional Motion Estimation)의 선택적 수행을 통한 HEVC (High Efficiency Video Coding)의 부호화 고속화 방법을 제안한다. HEVC 는 H.264/AVC 에 비해 약 2 배의 압축 효율을 보이지만, 쿼드트리 구조의 재귀적 호출은 복잡도를 크게 증가시켰다. 이러한 이유로 인하여 HEVC 부호화기의 고속 모드 결정 및 고속화 연구가 활발히 진행되고 있다. 본 논문에서는 HEVC 부호화기 중 가장 높은 복잡도를 갖는 화면 간 예측 모드의 부화소 움직임 추정 (FME: Fractional Motion Estimation)의 선택적 수행을 통하여 부호화기를 고속화하는 방법을 제안한다. 제안하는 방법을 HEVC 레퍼런스 소프트웨어인 HM-12.0 에 적용하여 평균 2.0%의 BD-BR 가 증가하였으나, 평균 36.0%의 부호화 시간 감소 효과를 얻을 수 있었다.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.827-830
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• 1998

멀티미디어 응용분야에 사용하는 데이터는 매우 크다. 이러한 대용량의 데이터를 관리하기 위해서 압축은 반듯이 필요하다. 본 논문에서는 허프만 부호화, 복호호 과정의 불규칙한 정렬구조와, 검색과정을 없애서 고속의 허프만 부호화 및 복호화가 가능한 허프만 코덱의 하드웨어 구조를 제안하였다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.1
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• pp.32-39
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• 2002

Vector quantization for image compression needs expensive encoding time to find the closest codeword to the input vector. This paper proposes a search algorithm for fast vector quantization encoding. Firstly, we derive a robust condition based on the efficient topological structure of the codebook to dramatically eliminate unnecessary matching operations from the search procedure. Then, we Propose a fast search algorithm using the elimination condition. Simulation results show that with little preprocessing and memory cost, the encoding time of the proposed algorithm is reduced significantly while the encoding quality remains the same with respect to the full search algorithm. It is also found that the Proposed algorithm outperforms the existing search algorithms.

• The Journal of the Korea Contents Association
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• v.14 no.9
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• pp.102-109
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• 2014

Intra prediction in HEVC is also significantly improved from H.264/AVC with the increased prediction modes up to 35 that results in increase of the complexity cost. Hence, a fast intra mode decision algorithm is required for real-time applications. A fast intra mode decision is proposed in this paper for further complexity reduction in addition to the RMD (Rough Mode Decision) that has been adopted into the HEVC reference software, referred to as HM, for fast intra prediction. The proposed method reduces the complexity of intra mode decision by limiting the number of search modes in both steps of RMD and the final mode decision. Experimental results show that the proposed method provide about 13.2% encoding time reduction with 1.0% BD-rate increase on average over test sequences in HM 12.0.