• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.3
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• pp.1195-1211
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• 2016

The emerging video coding standard High Efficiency Video Coding (HEVC) has shown almost 40% bit-rate reduction over the state-of-the-art Advanced Video Coding (AVC) standard but at about 40% computational complexity overhead. The main reason for HEVC computational complexity is the inter prediction that accounts for 60%-70% of the whole encoding time. In this paper, we propose several fast coding unit (CU) encoding schemes based on the Merge mode and motion estimation information to reduce the computational complexity caused by the HEVC inter prediction. Firstly, an early Merge mode decision method based on motion estimation (EMD) is proposed for each CU size. Then, a Merge mode based early termination method (MET) is developed to determine the CU size at an early stage. To provide a better balance between computational complexity and coding efficiency, several fast CU encoding schemes are surveyed according to the rate-distortion-complexity characteristics of EMD and MET methods as a function of CU sizes. These fast CU encoding schemes can be seamlessly incorporated in the existing control structures of the HEVC encoder without limiting its potential parallelization and hardware acceleration. Experimental results demonstrate that the proposed schemes achieve 19%-46% computational complexity reduction over the HEVC test model reference software, HM 16.4, at a cost of 0.2%-2.4% bit-rate increases under the random access coding configuration. The respective values under the low-delay B coding configuration are 17%-43% and 0.1%-1.2%.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2012.07a
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• pp.361-364
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• 2012

MPEG과 ITU-T에서 최근 표준화가 진행되고 있는 HEVC는 H.264/AVC에 비해, CU(coding unit), PU(prediction unit), TU(transform unit)의 다양한 형태 분할 단위를 갖는 것을 큰 특징으로 한다. 이 중, CU와 TU는 쿼드트리 형태의 재귀적 분할 구조를 가지도록 구성되는데, 압축 효율은 향상시키지만 높은 부호화 복잡도를 갖는 단점이 있다. 본 논문에서는 이러한 재귀적 분할 구조를 변환하여 가장 작은 CU의 정보를 병합하여 큰 CU의 정보를 빠르게 결정하는 방법을 제안한다. 제안한 방법을 HEVC의 CU 부호화에 적용한 결과, 부호화 복잡도를 32-45% 가량 감소시키면서 압축 효율 하락은 0.6-0.9%로 억제할 수 있었다. 또한, HM6.1에 구현되어 있는 고속 탐색 알고리즘과 비교 할 경우, 압축 효율 하락을 0.2-0.3%로 억제하면서 부호화 복잡도를 8-12% 감소시킬 수 있었다.

• 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.

• Journal of Broadcast Engineering
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• v.24 no.6
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• pp.1134-1142
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• 2019

Detection of double compression is one of the most efficient ways of remarking the validity of videos. Many methods have been introduced to detect HEVC double compression with different coding parameters. However, HEVC double compression detection under the same coding environments is still a challenging task in video forensic. In this paper, we introduce a novel method based on the frame partitioning information in intra prediction mode for detecting double compression in with the same coding environments. We propose to extract statistical feature and Deep Convolution Neural Network (DCNN) feature from the difference of partitioning picture including Coding Unit (CU) and Transform Unit (TU) information. Finally, a softmax layer is integrated to perform the classification of the videos into single and double compression by combing the statistical and the DCNN features. Experimental results show the effectiveness of the statistical and the DCNN features with an average accuracy of 87.5% for WVGA and 84.1% for HD dataset.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.4
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• pp.1730-1747
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• 2018

Multi-view video plus depth (MVD) is a mainstream format of 3D scene representation in free viewpoint video systems. The advanced 3D extension of the high efficiency video coding (3D-HEVC) standard introduces new prediction tools to improve the coding performance of depth video. However, the depth video in 3D-HEVC is time consuming. To reduce the complexity of the depth video inter coding, we propose a fast coding unit (CU) size and mode decision algorithm. First, an off-line trained Bayesian model is built which the feature vector contains the depth levels of the corresponding spatial, temporal, and inter-component (texture-depth) neighboring largest CUs (LCUs). Then, the model is used to predict the depth level of the current LCU, and terminate the CU recursive splitting process. Finally, the CU mode search process is early terminated by making use of the mode correlation of spatial, inter-component (texture-depth), and inter-view neighboring CUs. Compared to the 3D-HEVC reference software HTM-10.0, the proposed algorithm reduces the encoding time of depth video and the total encoding time by 65.03% and 41.04% on average, respectively, with negligible quality degradation of the synthesized virtual view.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.260-264
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• 2013

This paper proposes a fast enhancement layer coding method to reduce computational complexity for Scalable HEVC (SHVC) which is based on High Efficiency Video Coding (HEVC). The proposed method decreases encoding time by simplifying Rate Distortion Optimization (RDO)for enhancement layers (EL). The simplification is achieved by restricting CU depths based on the correlation of coding unit (CU) depths between adjacent layers and scalability (spatial or quality) of EL. Comparing with the performance of SHM 1.0 software encoder, the proposed method reduces the encoding time by up to 31.5%.

• ETRI Journal
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• v.35 no.2
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• pp.270-280
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• 2013

A fast intra-prediction method is proposed for High Efficiency Video Coding (HEVC) using a fast intra-mode decision and fast coding unit (CU) size decision. HEVC supports very sophisticated intra modes and a recursive quadtree-based CU structure. To provide a high coding efficiency, the mode and CU size are selected in a rate-distortion optimized manner. This causes a high computational complexity in the encoder, and, for practical applications, the complexity should be significantly reduced. In this paper, among the many predefined modes, the intra-prediction mode is chosen without rate-distortion optimization processes, instead using the difference between the minimum and second minimum of the rate-distortion cost estimation based on the Hadamard transform. The experiment results show that the proposed method achieves a 49.04% reduction in the intra-prediction time and a 32.74% reduction in the total encoding time with a nearly similar coding performance to that of HEVC test model 2.1.

• Journal of Broadcast Engineering
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• v.18 no.2
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• pp.271-282
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• 2013

Recently, ITU-T/VCEG and ISO/IEC MPEG have started a new joint standardization activity on video coding, called High Efficiency Video Coding (HEVC). This new standard gives significant improvement in terms of picture quality for high resolution video. The main challenge in this upcoming standard is the time complexity. In this paper we have focused on CU splitting algorithm. We have proposed a novel algorithm which can terminate the CU splitting process early based on the RD cost of the parent and current level and the motion vector value of the current CU. Experimental result shows that our proposed algorithm gives on average more than about 10% decrement in time over ECU [8] with on average 1.78% of BD loss on the original.

• Journal of Broadcast Engineering
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• v.16 no.5
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• pp.762-772
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• 2011

In this paper, a method of rate control for constant bitrate (CBR) coding of High Efficiency Video Coding (HEVC) is addressed. The existing rate control of H.264/AVC may not provide exact rate control in the case of hierarchical coding structure since it doesn't consider the characteristics of the hierarchical coding structure. It is expected that a rate control is added to the reference software called HM for CBR encoding in the near future. More accurate rate control may be required in a hierarchical structure of random access (RA) mode defined in the common test condition of HM. In this paper, we propose a method of rate control based on quadratic Rate-Distortion (R-D) model considering temporal layers and frame types in hierarchical coding structure for efficient rate control. In the consideration of the trade-off relationship between the bit fluctuation and the average PSNR, both of frame and coding unit (CU) are set as the basic unit of rate control. The performance of the proposed rate control method is verified by simulations along with the trade-off relationships for the both cases of basic unit.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2018.06a
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• pp.270-271
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• 2018

본 논문에서는 새로이 시작된 비디오 압축 표준인 VVC(Versatile Video Coding)의 인-루프(in-loop) 필터링을 위한 CNN 구조를 제안한다. 제안하는 CNN 구조는 복호화된 영상을 입력으로 하고 원본 영상과 복호화된 영상의 오차를 손실함수로 사용하여 학습을 진행한다. 또한, 비디오 부호화에서의 다양한 크기의 CU(Coding Unit)를 고려한 다양한 크기의 컨볼루션 필터를 사용하여 특징을 추출하는 구조에 기반하고 있다. 실험을 통하여 제안한 CNN 기반의 필터링이 VVC 의 시험모델인 VTM(VVC Test Model)의 인-루프 필터링의 성능을 개선할 수 있음을 확인하였다.