• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.9C
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• pp.697-703
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• 2008

The H.264/AVC video coding standard provides higher coding efnciency compared to the conventional MPEG-2 standard. Since a lot of videos have been encoded using MPEG-2, the format conversion from MPEG-2 to H.264 is essential. In this paper, we propose an efficient method for the conversion of DCT coefficients to H.264/AVC transform coefficients. This conversion is essential, since $8{\times}8$ DCT and $4{\times}4$ integer transform are used in MPEG-2 and H.264/AVC, respectively. The mathematical analysis and computer simulation show that the computational complexity of the proposed algorithm is reduced compared to the conventional algorithm, while the loss caused by the conversion is negligible.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.8C
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• pp.729-737
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• 2007

The H.264/AVC video coding standard provides higher coding efficiency compared to the conventional MPEG-2 standard. Since a lot of videos have been encoded using MPEG-2, the format conversion from MPEG-2 to H.264 is essential. In this paper, we propose an efficient method for the conversion of DCT coefficients to H.264/AVC transform coefficients. This conversion is essential, since $8{\times}8$ DCT and $4{\times}4$ integer transform are used in MPEG-2 and H.264/AVC, respectively. The mathematical analysis and computer simulation show that the computational complexity of the proposed algorithm is reduced compared to the conventional algorithm, while the loss caused by the conversion is negligible.

• Journal of Broadcast Engineering
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• v.24 no.4
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• pp.660-669
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• 2019

Recently, with the development of three-dimensional scanning devices and multi-dimensional array cameras, research is continuously conducted on techniques for handling three-dimensional data in application fields such as AR (Augmented Reality) / VR (Virtual Reality) and autonomous traveling. In particular, in the AR / VR field, content that expresses 3D video as point data has appeared, but this requires a larger amount of data than conventional 2D images. Therefore, in order to serve 3D point cloud content to users, various technological developments such as highly efficient encoding / decoding and storage, transfer, etc. are required. In this paper, V-PCC bit stream created using V-PCC encoder proposed in MPEG-I (MPEG-Immersive) V-PCC (Video based Point Cloud Compression) group, It is defined by the MPEG-DASH (Dynamic Adaptive Streaming over HTTP) standard, and provides to be composed of segments. Also, in order to provide the user with the information of the 3D coordinate system, the depth information parameter of the signaling message is additionally defined. Then, we design a verification platform to verify the technology proposed in this paper, and confirm it in terms of the algorithm of the proposed technology.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.337-340
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• 2001

본 논문에서는 MPEG가 비디오 스트림의 형상 정보를 클러스터링 하여 VO(Visual Object)의 동작을 요약하는 새로운 방법을 제안한다. 제안하는 방법은 MPEG-4 비트 스트림의 디코딩 없이 형상 정보를 근사화 한다. 그리고 사용자가 입력한 질의 VOP(Video Object Plane)와 VO의 각 VOP와의 NMHD(Normalized Mean Hausdorff Distance)를 구한 후 클러스터링을 수행하여 키 영역을 분리해낸다. 클러스터링에 의해 시간적으로 분리된 영역의 지속성을 고려하여 Rank를 매김으로써 사용자가 원하는 수의 키 VOP를 선택할 수 있게 한다. 제안하는 방법은 클러스터링을 사용함으로써 키 VOP를 선정하였으며, Rank와 질의 VOP를 사용하여 사용자와의 상호작용이 가능하다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1998.06a
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• pp.121-126
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• 1998

DV(Digital Video) 영상 압축 방식에서 MPEG-2로 변환할 때 처리단계를 줄이기 위하여 DCT 영역에서 변환하였다. DV 방식의 색차신호 포맷인 4:1:1에서 4:2:2로 변환하고, 2-4-8 DCT 모드를 변환할 때 행렬을 이용하여 변환함으로써 중간과정을 줄였으며, DCT 영역에서 MPEG-2의 율 제어를 구현하였다. DV에서 만든 DCT 계수를 이용하여, 단계적으로 움직임 추정을 함으로써 전역탐색 블록 매칭 방식보다 처리 속도를 개선하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.4
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• pp.315-324
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• 2005

VOD(video on demand) is a video service by users' order, that is, a video service on demand. That means the users can select and watch the video content that has been saved on sewer, out of broadcasting in the usual process like TV. At present the client of VOD system bases on PC. As the PC-based client uses the software MPEG decoder, the main processor specification has an effect on the capacity. Also people, who don't know how to use their PC, cannot be provided the VOD service. The purpose of this paper is to show the process of the development the VOD client system Into the embedded type with hardware MPEG-4 decoder. The main processor is the SC1200 of x86 Family in National Semiconductor with a built-in video processor and the memory is 128Mbyte SDRAM. Also, in order that the VOD service can be provided using the Internet, the Ethernet controller is included. As the hardware MPEG-4 decoder is used in the embedded VOD client system, which is developed, it can make the low capacity of the main processor. Therefore it is able to be developed as a low-price system. The embedded VOD client system is easy for anyone to control easily with the remote control and can be played through TV.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10b
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• pp.259-261
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• 1999

본 논문은 MPEG-2 TM 5 video 부호기의 전체구조 및 처리과정을 기술한다. MPEG-2는 저장 매체, 통신, 방송 매체 등을 위한 동영상 압축이 표준이다. MPEG-2 압축 방법에는 공간적 압축과 시간적 압축 방법이 있다. 공간적 압축 방법에는 화면에서의 중복성을 줄이기 위한 표본화 주파수(4:4:4, 4:2:2, 4:2:0, format), DCT, scanning(zigzag 혹은 alternate scanning)과 quantization이 있고 시간적 압축 방법에는 움직임 예측(motion estimation)과 I, P, B-picture를 사용하는 방법이 있다. 본 논문에서는 MPEG-2 부호기의 핵심을 전체 구조, DPCM, MPEG bitstream syntax, MPEG-2 부호화 알고리즘, 움직임 예측, 움직임 벡터, rate control 그리고 가변길이 코딩(variable length coding)으로 구분하여 소개한다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.39 no.6
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• pp.641-651
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• 2002

Recently, many advanced video application services over the mobile wireless networks have required a transcoder which can efficiently reduce the size of compressed video bitstreams. The transcoder can be worked in either the spatial domain or the DCT domain. In this paper, we propose a new fast hybrid-type transcoder which can efficiently reduce the frame size with keeping the visual quality. The proposed scheme consists of two major processes: a transform domain process and a spatial domain process. We also propose a scheme for coding mode selection and motion vector refinement. Experimental results show that our approach can reduce the computational complexity more than any other conventional spatial-domain transcoder with keeping the visual quality.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.8B
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• pp.1424-1435
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• 2000

A bit-rate controller that can achieve a constant bit rate when coding object-based video sequences is an important part to achieve an adaptation to bit-rate constraints, desired video quality, distribution of bits among objects, relationship between texture and shape coding, and determination of frame skip or not. Therefore we design content-based bit rate controller which will be used for relevant bit-rate control. The implementation is an extension of MPEG-4 rate control algorithm which employs a quadratic rate-quantizer model. The importance of different objects in a video is analyzed and segmented into a number of VOPs which are adaptively bit-allocated using the object-based modelling. Some test sequences are observed by a number of non-experts and interests in each object are analysed. The initial total target bit-rate for all objects is obtained by using the proposed technique. Then the total target bits are jointly analyzed for preventing from overflow or underflow of the buffer fullness. The target bits are distributed to each object in view of its importance, not only of statistical analysis such as motion vector magnitude, size of object shape, and coding distortion of previous frame. The scheme is compared with the rate controller adopted by the MPEG-4 VM8 video coder by representing their statistics and performance.

• IEMEK Journal of Embedded Systems and Applications
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• v.2 no.3
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• pp.129-137
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• 2007

MPEG-4 FGS is one of scalable video coding schemes specified In ISO/IEC 14496-2 Amendment 2, and particularly standardized as a scheme for providing fine granular quality and temporal scalabilities. In this paper, we propose a sign-bit reduction technique in embedded bit-plane coding to enhance the coding efficiency of MPEG-4 FGS system. The general structure of the FGS system for the proposed scheme is based on the standard MPEG-4 FGS system. The proposed FGS enhancement-layer encoder takes as input the difference between the original DCT coefficient and the decision level of the quantizer instead of the difference between the original DCT coefficient and its reconstruction level. By this approach, the sign information of the enhancement-layer DCT coefficients can be the same as that of the base-layer ones at the same frequency index in DCT domain. Thus, overhead bits required for coding a lot of sign information of the enhancement-layer DCT coefficients in embedded bit-plane coding can be removed from the generated bitstream. It is shown by simulations that the proposed FGS coding system provides better coding performance, compared to the MPEG-4 FGS system in terms of compression efficiency.