• Journal of KIISE:Information Networking
• /
• v.30 no.6
• /
• pp.695-704
• /
• 2003

A wavelet-based video stream is more susceptible to the network transmission errors than DCT-based video. This is because bit-errors in a subband of a video frame affect not only the other subbands within the current frame but also the subsequent frames. In this paper, we propose a video source coding scheme called IPC(Intra Prediction Coding) scheme in order to reduce the error propagation to the subsequent frames. In the proposed scheme, a subband except LL subband in the current frame refers to the lower-level subband within the same frame. This reduces the error propagation to subsequent frames. We evaluated the performance of our proposed scheme in the simulated wireless network environment. As a result of tests, it was shown that the proposed algorithm shows better performance than MRME in a heavy motion image sequence while IPC outperforms MRME at a high bit-rate in small motion image sequence.

• Journal of Advanced Navigation Technology
• /
• v.13 no.4
• /
• pp.523-531
• /
• 2009

In this study, we propose a joint source/channel rate control algorithm for video encoder targeting packet erasure channel. Based on the buffer constraints of video communication systems, encoding rate constraint is presented. After defining source distortion models for coded and skipped video frames and a channel distortion model for packet errors and their propagation, an average distortion model of received video is proposed for a given encoding window. Finally, we define an optimization problem to minimize the average distortion for given channel rates and packet loss rates by controlling spatio-temporal parameters of source video and FEC block sizes. Then, we propose a window-based algorithm to solve the problem in real-time.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2015.07a
• /
• pp.555-556
• /
• 2015

MPEG 의 Royalty-Free 비디오 코덱의 하나로 표준화 중인 IVC(Internet Video Coding)에서는 화면내(intra) 예측부호화에서 부호화 이득을 위하여 $4{\times}4$ 블록 예측 및 $4{\times}4$ 블록 변환을 포함하고 있다. 반면, 화면간(inter) 예측부호화에서는 $16{\times}16$ 블록에서 최소 $8{\times}8$ 블록까지의 가변크기 블록에 대한 예측만 가능하다. 보다 복잡한 영상의 경우 보다 작은 블록에 대한 화면간 예측을 통하여 부호화의 성능 개선을 개선할 수 있다. 본 논문에서는 기존의 화면간 예측의 블록 크기를 $4{\times}4$ 블록까지 확장하여 화면간 예측부호화 성능을 개선한다. 실험결과 제안기법은 기존의 ITM 12.0 대비 다양한 테스트 시퀀스의 휘도성분에서 평균적으로 비트율 절감의 이득은 없으나 대부분의 클래스에서 성능개선을 보였고 추가적인 최적화가 필요함을 확인하였다.

• Journal of Digital Contents Society
• /
• v.18 no.6
• /
• pp.1009-1015
• /
• 2017

Recently, video surveillance is becoming more and more common as many camera are installed due to crime, terrorism, traffic and security. And systems that control cameras are becoming increasingly general. Video input from the installed camera is monitored by the multiscreen at the central control center, it is essential to simultaneously monitor multiscreen in real-time to quickly respond to situations or dangers. However, monitoring of multiscreen in a mobile environment such as a smart phone is not applied to hardware specifications or network bandwidth problems. For resolving these problems, in this paper, we propose a system that can monitor multiscreen in real-time in mobile-phone environment. We reconstruct the desired multiscreen through transcoding, it is possible to monitor continuously video streaming of multiple cameras, and to have the advantage of being mobile in mobile-phone environment.

• The KIPS Transactions:PartB
• /
• v.13B no.3 s.106
• /
• pp.245-254
• /
• 2006

In this work, a new rate control algorithm for transmission of H.264/AVC video bit stream through CBR(constant bit rate) channel is proposed. The proposed algorithm predicts target bit rate and MAD(mean of absolute difference) for current frame considering image complexity variance between neighboring backward and current images. In details, respective linear regression analysis for MAD and encoded bit rate against image complexity variance produce correlation parameters. Additionally, it uses frame skip technique to maintain bit stream within a manageable range and protect buffer from overflow or underflow. Implementation and experimental results show that the proposed algorithm can provide accurate bit allocation, and can effectively visual degradation after scene changes. Also our proposed algorithm encodes the video sequences with less frame skipping compared to the existing rate control for H.264/AVC.

• Electronics and Telecommunications Trends
• /
• v.12 no.1 s.43
• /
• pp.27-42
• /
• 1997

영상 합성 기술이란 영화 및 비디오 제작에 있어 비디오 화면을 다양한 효과를 사용하여 편집하는 기술이다. 비디오 분야에서 디지털 기술이 도입되어 사용된 이 기술은 영상 산업을 급격히 변화시키는 응용 기술의 하나로 본 고에서는 이 분야에서 현재 사용되는 시스템의 특징과 그러한 시스템의 공통된 기술을 분석하여 이 분야의 기술 개발에 활용하고자 한다.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2015.10a
• /
• pp.1603-1606
• /
• 2015

본 논문은 JCT-VC의 표준 레퍼런스 소프트웨어인 HM15.0을 통해서 HEVC 비디오를 다양한 크기와 모드로 인코딩한 뒤 동일한 워크스테이션에서 디코딩 작업을 수행한다. 이 결과로 나오는 디코딩 시간을 토대로 비디오 크기별 디코딩 복잡도에 관한 다중회귀분석을 진행한다.

• Journal of KIISE
• /
• v.41 no.11
• /
• pp.900-910
• /
• 2014

Multi-view video is obtained by capturing one three-dimensional scene with many cameras at different positions. The computational complexity of multi view video coding increases in proportion to the number of cameras. To reduce computational complexity and maintain the image quality, improved prediction structure and motion estimation method is proposed in this paper. The proposed prediction structure exploits an average distance between the current picture and its reference pictures. The proposed prediction structure divides every GOP into several groups to decide the maximum index of hierarchical B layer and the number of pictures of each B layer. And the proposed motion estimation method uses a hierarchical search strategy. This strategy method consists of modified diamond search pattern, progressive diamond search pattern and modified raster search pattern. Experiment results show that the complexity reduction of the proposed prediction structure and motion estimation method over JMVC (Joint Multiview Video Coding) reference model using hierarchical B pictures of Fraunhofer-HHI and TZ search method can be up to 40~70% while maintaining similar video quality and bit rates.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.12C
• /
• pp.721-726
• /
• 2011

The compression performance of HEVC (high efficiency video coding) is improved 40%, compared to H.264/AVC. Since the existing 3D video CODEC is based on H.264/AVC or MPEG-2, we can improve the compression performance when we use the proposed stereoscopic video coding method based on HEVC. Since the stereoscopic video has the temporal and inter-view correlations, the videos of the left and right cameras encode together to improve the performance. Especially, we implemented the proposed technique using HM(HEVC test model) 3.4. To compare the performance of the proposed method, we only compare the right view video which is coded using the inter-view prediction. The proposed method which is considered inter-view correlation is improved the performance which BDBR reduce about 36.24% and BDPSNR increase approximately 1.19 dB compared to the separated-coding method.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.33 no.4C
• /
• pp.321-329
• /
• 2008

H.264/AVC video coding standard enables a considerably higher improvement in coding efficiency compared with previous standards such as MPEG-2, H.263 and MPEG-4. To achieve this, for each macro-block in H.264/AVC, Rate-Distortion Optimization (RDO) technique is employed to select the best motion vector, reference frame, and macro-block mode. As a result, computational complexity is increased significantly whereas RDO achieve higher improvement. This paper presents fast intra mode selection algorithm based on constraints of frequency characteristics which are derived from intra coding modes of H.264/AVC. First of all, we observe the features of each intra mode through the frequency analysis of image. And then proposed Frequency Error Costs (FECs) are calculated to select the best mode which has minimum cost. Computational complexity is considerably reduced because rate-distortion costs only calculate the candidate modes which are set of best mode and its neighbouring two modes. Experimental results show that proposed algorithm reduces the complexity dramatically maintaining the rate-distortion performance compared with H.264/AVC reference software.