• The Journal of the Korea Contents Association
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• v.17 no.5
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• pp.1-7
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• 2017

Joint Collaborative Team on Video Coding (JCT-VC) of ISO/IEC MPEG and ITU-T developed the HEVC Screen Content Coding (HEVC SCC) standard as the HEVC extension for the screen content video coding. The Intra Block Copy (IBC) is the most effective tool adopted in HEVC SCC and predicts current block from already reconstructed neighboring blocks in the same picture. To reduce the amount of data in BV (Block Vector) to be transmitted, a BV predictor (BVP) is used to generate the BV differences in the IBC BV coding. In this paper, we analyze the current BV prediction process using HEVC reference software SCM-2.0 and SCM-4.0. Based on the analysis results, we propose an improved BVP candidate selection algorithm by adding a search process for adjacent BVs in addition to the existing spatial BVP candidates. Experimental results show that the BD-rate reduction of our proposed improvements ranges from 0.2% to 1%.

• Broadcasting and Media Magazine
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• v.24 no.4
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• pp.102-108
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• 2019

VVC(Versatile Video Coding)는 H.264/AVC(Advanced Video Coding)와 H.265/HEVC(High Efficiency Video Coding)의 엔트로피 코딩 기술로 사용되었던 CABAC(Context-based Adaptive Binary Arithmetic Coding)을 기반으로하여 압축율과 처리율을 향상시킬 수 있는 다양한 기술들이 채택되어 현재 CD(Committee Draft)가 완성되었고 참조 모델인 VTM6.0이 정식으로 배포되었다. 본 논문에서는 VVC Draft 6에 채택된 엔트로피 코딩 관련 기술들과 H.265/HEVC의 엔트로피 코딩의 차이점을 설명하고 엔트로피 코딩의 압축 성능과 엔트로피 코딩의 복잡도를 분석한다.

• Broadcasting and Media Magazine
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• v.15 no.4
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• pp.95-107
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• 2010

최근 MPEG에서는 ITU-T와 함께 JCT-VC(Joint Collaboration Team on Video Coding)를 구성하여 H.264/AVC 보다 두 배 이상 높은 고효율의 비디오 압축 표준을 진행하고 있으며, 이 새로운 표준을 가칭으로 HEVC(High Efficiency Video Coding)라 부른다. HEVC는 기존의 비디오 압축 표준들과 같이 하이브리드 부호화 구조를 사용하고 있으며, 고해상도 및 고효율의 압축을 실현하기 위해서 많은 새로운 기술들이 소개되었다. UHD급 이상의 고해상도 영상을 위해 큰 블록 단위의 부호화 처리와 변환 부호화 기술이 제안되었다. 그리고 H.264/AVC의 화면 내 예측과 화면 간 예측에 대한 성능 향상을 위해 많은 기술들이 소개되었다. 본 기고에서는 다양한 HEVC 기술 중에 엔트로피 부호화 방법에 대해서 소개한다.

• Journal of Broadcast Engineering
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• v.19 no.5
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• pp.627-630
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• 2014

The latest video coding standard, high efficiency video coding (HEVC) achieves high coding efficiency by employing a quadtree-based coding unit (CU) block partitioning structure which allows recursive splitting into four equally sized blocks. At each depth level, each CU is partitioned into variable sized blocks of prediction units (PUs). However, the determination of the best CU partition for each coding tree unit (CTU) and the best PU mode for each CU causes a dramatic increase in computational complexity. To reduce such computational complexity, we propose a fast PU decision algorithm that early terminates PU search. The proposed method skips the computation of R-D cost for certain PU modes in the current CU based on the best mode and the rate-distortion (RD) cost of the upper depth CU. Experimental results show that the proposed method reduces the computational complexity of HM12.0 to 18.1% with only 0.2% increases in BD-rate.

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.1
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• pp.22-27
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• 2015

Transform-domain JND (Just Noticeable Difference)-based for PVC (Perceptual Video Coding) is often performed in quantization processes to effectively remove perceptual redundancy. This study examined the JND-suppression effects on quantized coefficients of transform in HEVC (High Efficiency Video Coding). To reveal the JND-suppression effect in quantization, the properties of the floor functions were used for modeling the quantized coefficients, and a JND-adjustment process in an HEVC-compliant PVC scheme was used to tune the JND values by analyzing the JND suppression effect. In the experimental results, the bitrate reduction decreases slightly, but the PSNR and perceptual quality are improved significantly when the proposed JND adjustment process is applied.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.06a
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• pp.176-179
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• 2013

본 논문에서는 JCT-VC 에서 2013 년 1 월에 표준화가 완료된 High Efficiency Video Coding (HEVC)과 구글에서 2013 년 6 월에 개발 완료 예정인 VP9 의 압축 효율 비교를 수행한다. HEVC 는 UHD 등 고화질 방송 등에 대응하도록 디자인 되었으며, VP9 은 유튜브 (YouTube) 등과 같은 인터넷 비디오 스트리밍에 적합하도록 디자인되었다. VP9 의 경우 HEVC 와는 달리 로열티 프리 (royalty-free)를 지향하며 오픈소스 (open source) 방식으로 개발이 진행되고 있다. 본 논문에서는 HEVC 와 VP9 의 디자인 차별점을 소개하고, 랜덤 액세스 환경(Random Access, RA)과 저지연 환경 (Low Delay, LD)에서 HEVC 와 VP9 의 압축 효율을 비교한다. 실험 결과에 따르면, 방송 및 패키지 미디어 등에서 많이 사용될 랜덤 액세스 환경에서는 VP9 이 HEVC 대비 32.7% 열세를 보인다. 비디오 컨퍼런스등과 같은 저지연 환경에서는 VP9 이 HEVC 대비 26.7% 열세를 보인다. VP9 의 경우 개발이 완료된 것이 아니므로, 향후 압축 효율의 향상이 있을 것으로 기대된다.

• Journal of Broadcast Engineering
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• v.23 no.4
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• pp.495-502
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• 2018

JVET (Joint Video Exploration Team) which explored evolving technologies of video coding with capabilities beyond HEVC (High Efficiency Video Coding), released a references software codec named the Joint Exploration Model (JEM) for performance verification of coding technologies. JEM has 67 intra prediction modes that extend the 35 modes of HEVC for intra prediction. Therefore, the enhancement of the coding performance is limited due to the overhead of prediction mode coding. In this paper, we analyze the probabilities of prediction modes selections, and then we propose a more efficient intra prediction mode coding based on the results of analyzed mode occurrence. In addition, we propose a context modeling for CABAC (Context-Adaptive Binary Arithmetic Coding) of the proposed mode coding. Experimental results show that the BD-rate gain is 0.02% on the AI (All Intra) coding structure compared to JEM 7.0. We need to optimize context modeling for additional coding performance enhancement.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.5
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• pp.114-124
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• 2014

HEVC is a state-of-the-art video coding standard developed by JCT-VC. HEVC provides about 2 times higher subjective coding efficiency than H.264/AVC. One of the main goal of HEVC development is to efficiently coding UHD resolution video so that HEVC is expected to be widely used for coding UHD resolution video. Decoding such high resolution video generates a large number of memory accesses, so a decoding system needs high-bandwidth for memory system and/or internal communication architecture. In order to determine such requirements, this paper presents an analysis of the memory access complexity for HEVC decoder. we first estimate the amount of memory access performed by software HEVC decoder on an embedded system and a desktop computer. Then, we present the memory bandwidth models for HEVC decoder by analyzing the data flow of HEVC decoding tools. Experimental results show the software decoder produce 6.9-40.5 GB/s of DRAM accesses. also, the analysis reveals the hardware decoder requires 2.4 GB/s of DRAM bandwidth.

• Journal of Broadcast Engineering
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• v.18 no.6
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• pp.816-822
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• 2013

The latest video coding standard HEVC was developed by the joint work of JCT-VC(Joint Collaborative Team on Video Coding) from ITU-T VCEG and ISO/IEC MPEG. The HEVC standard reduces the BD-Bitrate of about 50% compared with the H.264/AVC standard. However, using the various methods for obtaining the coding gains has increased complexity problems. The proposed method reduces the complexity of HEVC by using both CPU parallel processing and GPU-accelerated processing. The experiment result for UHD($3840{\times}2144$) video sequences achieves 15fps encoding/decoding performance by applying the proposed method. Sooner or later, we expect that the H/W speedup of data transfer rates between CPU and GPU will result in reducing the encoding/decoding times much more.

• Journal of Broadcast Engineering
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• v.19 no.3
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• pp.307-315
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• 2014

A new modified lossless intra-coding method based on a cross residual transform is applied to HEVC(High Efficiency Video Coding). The HEVC standard including a multi-directional spatial prediction method to reduce spatial redundancy encodes the pixels in a PU (Prediction Unit) by using neighboring pixels. In the new modified lossless intra-coding method, the spatial prediction is performed by pixel-based DPCM but is implemented by block-based manner by using cross residual transform on the HEVC standard. The experimental results show that the new lossless intra-coding method reduces the bit rate of approximately 8.4% in comparison with the lossless-intra coding method in the HEVC standard and the proposed method results in slightly better compression ratio than the JPEG2000 lossless coding.