• Journal of Broadcast Engineering
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• v.8 no.2
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• pp.181-197
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• 2003

Notion Compensation(MC) technique using Sub-Band Coding with the hierarchical structure is efficient to estimate real motion. In the hierarchical pyramid method, low-band MC pyramid method is popular, where the upper layer estimate the glover motion and next lower layer estimate the local motion. The low-band MC pyramid scheme has two problems. First, because the quantization errors at lower layer are accumulated when using coding and quantizing, it is impossible to search the exact Motion Vector(MV) Second, because of the top-down search problem in the hierarchical structure, MV mismatch in upper layer causes serious MV in lower layer So. we propose new hierarchical MC pyramid method based on edge classification. In this Paper, we show that the performance of proposed Pass-band motion compensation pyramid technique is better than low-band motion compensation pyramid. Also, in the pyramid motion estimation, we propose initial MV estimation scheme based on the edge-pattern classification. As a result, we find that PSNR was increased.

• Journal of Broadcast Engineering
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• v.16 no.1
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• pp.123-132
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• 2011

Recently, DVC (Distributed Video Coding) is receiving a lot of attention as one of the low complexity video encoding techniques suitable for various applications with computation-limited and/or power-limited environment, and is being actively studied for improving the coding efficiency. This paper proposes a rate-distortion based selective block encoding scheme. First, the motion information is obtained in the process of generating side information at decoder and received through the feedback channel, and then, based on this information, the proposed method performs a selective block encoding based on rate-distortion optimization. Experimental results show that the performance of the proposed scheme reaches up to 2.2 dB PSNR gain over the existing scheme. Moreover, it is shown that the complexity can be reduced by encoding parts of region considering rate-distortion cost.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1998.06a
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• pp.185-188
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• 1998

본 논문에서는 새로운 예측 방법을 사용한 웨이브릿 영상 압축 방식을 제안한다. 에지는 시각적으로 매우 중요한 성분이며 밴드간에도 높은 상관도를 가지고 있다. 또한 에지는 각 밴드의 성질에 맞는 일정한 방향을 가지고 있다. 본 논문에서는 자식 계수들의 배열이 밴드 방향에 따라 방향성을 가진다는 것을 예측에 이용하여 새로운 트리를 통해 영상을 압축하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2022.06a
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• pp.1236-1238
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• 2022

JVET 은 최신 비디오 부호화 표준인 VVC(Versatile Video Coding) 표준화를 완료한 후, VVC 보다 더 높은 압축 성능을 가지는 새로운 표준기술 탐색을 진행하고 있으며, 이를 위하여 참조 소프트웨어 ECM(Enhanced Compression Model)을 개발하고 있다. 현재 ECM4.0 에는 다양한 후보 구성 및 예측 성능 개선 기법을 추가하여 기존 VVC 의 GPM(Geometric Partitioning Mode)을 확장한 GPM-MMVD(GPM with merge MV differences), GPM-TM(GPM with template matching) 등을 채택하고 있다. 본 논문에서는 ECM 에 채택된 확장된 GPM 기술들의 각 기술 별 선택 빈도를 분석하고 이를 바탕으로 보다 효율적인 GPM 확장 모드 시그널링 방식을 제안한다. 또한 후보 탐색 알고리즘을 간소화한 복잡도 감소 기법을 제시한다. 실험결과 제안하는 시그널링 기법은 ECM4.0 대비 Y와 Cb, Cr 에서 각각 0.02%, 0.16%, 0.09% BD-rate 부호화 성능 향상을 보였고 GPM 인덱스 탐색 간소화 기법은 ECM4.0 대비 Y 와 Cr 에서 각각 0.02%, 0.18% BD-rate 부호화 성능 향상을 보였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2008.11a
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• pp.259-262
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• 2008

본 논문에서는 다시점 비디오와 깊이 정보의 상관도를 이용해서 현재 JVT(joint video team)에서 표준화 된 다시점 비디오 부호화 (multi-view video coding : MVC)의 참조 소프트웨어인 JMVM(joint multi-view video model)을 기반으로 하여 효율적인 다시점 비디오 압축 방법을 제안한다. 기존의 일반적인 비디오 부호화 방식은 단일 시점에 대한 비디오 부호화 기술이기 때문에 다시점 비디오 전송을 위해서는 시점 당 각각 전송 채널에 필요하다. 하지만 다시점 비디오 부호화 기법을 이용하게 되면, 단일 전송 채널을 이용하여 전송이 가능하다. 본 논문에서 제안된 방법은 입력된 다시점 입력 영상과 해당 하는 깊이 정보를 이용하여 시점 간의 예측 방법의 효율성을 높였다. 다시점 입력 영상과 깊이 정보의 전역 변이 벡터 (global disparity vector : GDV)의 상관도를 이용하였으며, 다시점 영상과 깊이 정보를 동시에 전송해야 할 경우 복잡도를 낮출 수 있고, 약 $0.01{\sim}0.1dB$의 PSNR 이득을 얻을 수 있다.

• Journal of Advanced Navigation Technology
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• v.14 no.1
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• pp.102-107
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• 2010

This paper presented a rate-distortion estimation method for effective mode decision in H.264/AVC. In this approach, in order to decide a mode, laplacian distribution modeling of DCT coefficients is utilized, which do not need to such process as quantization, entropy coding. From the simulation results, proposed a method showed that rate-distortion between proposed scheme and practical value was almost the same and performed 0.02dB of PSNR gain.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2016.06a
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• pp.204-206
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• 2016

본 논문에서는 template matching을 이용한 PMMVD(Pattern Matched Motion Vector Derivation)기술에 대해 움직임 추정 방식에 따라 복잡도를 분석한다. PMMVD 기술은 HEVC의 화면 간 예측 기술과는 다르게 움직임과 관련된 정보를 부호화하지 않으며, 복호화기에서 움직임 벡터를 추정하는 방식이다. 따라서 종래의 기술 대비 높은 효율이 발생하지만 복호화기의 복잡도는 급격히 증가하게 된다. 이러한 이유로 다양한 움직임 추정 방식에 따라 성능을 분석하여 최적의 조합을 찾는 것은 매우 중요한 이슈임을 알 수 있다. 이를 위하여 현재 JVET(Joint Video Exploration Team)에서 FVC(Future Video Coding)를 위해 발표한 참조 소프트웨이인 JEM 2.0(Joint Exploration Test Model 2)을 이용하여 실험을 수행하고 향후 연구 방향을 논의한다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.42 no.2 s.302
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• pp.131-142
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• 2005

The low rate speech coders under 4 kbit/s are based on sinusoidal transform coding (STC) or multiband excitation (MBE). Since the harmonic coders are not efficient to reconstruct the transient segments of speech signals such as onsets, offsets, non-periodic signals, etc, the coders do not provide a natural speech quality. This paper proposes method of a efficient transient model :d a multi-mode low rate coder at 2.4 kbit/s that uses harmonic model for the voiced speech, stochastic model for the unvoiced speech and a model using aperiodic pulse location tracking (APPT) for the transient segments, respectively. The APPT utilizes the harmonic model. The proposed method uses different models depending on the characteristics of LPC residual signals. In addition, it can combine synthesized excitation in CELP coding at time domain with that in harmonic coding at frequency domain efficiently. The proposed coder shows a better speech quality than 2.4 kbit/s version of the mixed excitation linear prediction (MELP) coder that is a U.S. Federal Standard for speech coder.

• Journal of Broadcast Engineering
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• v.15 no.5
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• pp.672-680
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• 2010

This paper presents an adaptive quantization matrix selection scheme for H.264 video encoding. Conventional H.264 coding standard applies the same quantization matrix to the entire video sequence without considering local characteristics in each frame. In this paper, we propose block adaptive selection of quantization matrix according to edge directivity of each block. Firstly, edge directivity of each block is determined using intra prediction modes of its spatially adjacent blocks. If the block is decided as a directional block, new weighted quantization matrix is applied to the block. Otherwise, conventional quantization matrix is used for quantization of the non-directional block. Since the proposed weighted quantization is designed based on statistical distribution of transform coefficients in accordance with intra prediction modes, we can achieve high coding efficiency. Experimental results show that the proposed scheme can improve coding efficiency by about 2% in terms of BD bit-rate.

• Journal of Broadcast Engineering
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• v.13 no.6
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• pp.804-816
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• 2008

In this paper, we propose an adaptive rate control in frame-level for real-time H.264/AVC. For given QP, bits according to video characteristics, and current frame is close correlation between the adjacent frames. Using the statistical characteristic, we obtain change of occurrence bit about QP to apply the bit amount by QP from the video characteristic and applied in the estimated bit amount of the current frame. In addition, we use weight with QP and occurrence bit amount that is statistical information of encoded previous frames. Simulation results show that the proposed rate control scheme achieves time saving of more than 99% over JM 12.1 rate control algorithm. Nevertheless, PSNR and bit rate were almost same as the performances of JM.