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MPEG 비트스트림의 비트율 변환을 위한 비트율 제어기 개발
박구만,이광직 서울産業大學校 2000 논문집 Vol.51 No.2
The concept of MPEG-2 transcoding is related to the changing or scaling the amount of data in a previously encoded MPEG bitstream. The development of the bit rate converting transcoder consists of three parts which are the coding structure, the bit rate controller and the quantizer. We introduced a new rate-quantization model based on the macroblock activity and DCT coefficients. This model can be commonly used among different type of pictures such as I-, P-, and B-pictures. A new bit rate control algorithm is proposed that uses a priori knowledge from the given bitstream and it showed a better performance over the MPEG-2 TM5 algorithm by the computer simulation.
Background Initialization by Spatiotemporal Similarity
박구만,Park, Goo-Man The Korean Institute of Broadcast and Media Engine 2007 방송공학회논문지 Vol.12 No.3
A background initialization algorithm based on the spatiotemporal similarity measure in a motion tracking system is proposed. From the accumulated difference between the base frame and the other frames in a subinterval, the regions affected by moving objects are located. The median is applied over the subsequence in the subinterval in which co-located regions share the similarity. The outputs from each subinterval are filtered by second stage median filter. The proposed method showed good results even in the busy and crowded sequences where the real background does not exit.
박구만 호남대학교 1997 호남대학교 학술논문집 Vol.18 No.4
For the consumer use VCR, the quantizer is selected based on CLASS and QNO. CLASS is determined for each DCT block according to the characteristics of the block, for example, the maximum value of AC coefficients. Six DCT blocks comprise a macroblock for which a QNO is determined. All of the quantizers defined in the specifications are numvbered from 0 to 15 by QNO. Different quantizers can be referenced by the same QNO and are discriminated by CLASS. In this paper, we propose a new method to determine these parameters, QNO and CLASS, for the selection of a quantizer per each DCT block. We first determine QNO for a macroblock and then fine-tune the quantizers by adjusting CLASS of each DCT block. For this we propose a modified quantizer map with a reduced set of quantizers, which preserves the compatibility with the conventional one. The results of our experiment show that our method outperforms the conventional method.
자유시점 비디오 기술동향 및 확장형 자유선택시점 개발 사례
박구만 한국통신학회 2019 정보와 통신 Vol.36 No.12
자유시점 비디오 기술은 부드럽게 시점을 이동시켜주는 기술이다. 본 고에서는 자유시점 비디오 기술을 제공하기 위한 구성요소와 최근까지의 개발동향을 소개한다. 본 기술은 기존의 영상기술들과 차별화되는 실감성을 제공하지만 동시에 대단히 많은 수의 카메라, 고성능 연산 장비, 많은 데이터량의 발생과 같은 해결해야할 과제들도 동시에 안고 있다. 이러한 점들을 해결하고자 하는 방법들에 대해서도 언급을 하였다. 또한 실제로 개발하고 있는 사례도 소개한다.