• Title/Summary/Keyword: H263 codec

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An Adaptive Rate-Distortion Optimization Method for H.264 Video Codec (H.264를 위한 적응적인 비트-왜곡 최적화 방법)

  • Oh, Kwan-Jung;Ho, Yo-Sung
    • Proceedings of the IEEK Conference
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    • 2005.11a
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    • pp.323-326
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    • 2005
  • Several video coding standards, such as MPEG-4 and H.263, have been investigated to reduce the resulting number of bits while pursuing the maximum video quality. The recent video coding standard, H.264, provides higher coding efficiency than previous coding standards by using the mode decision scheme. For mode decision, H.264 chooses the best macroblock mode among the several candidates using Lagrangian cost function which reflects both the rate and the distortion. H.264 employs only one rate-distortion optimization (RDO) model for all macroblocks. Since the characteristics of each macroblock is different, each macroblock should have its own RDO model. In this paper, we propose an adaptive rate-distortion optimization algorithm for H.264. We regulate the Lagrangian multiplier considering the picture type and characteristics of each macroblock.

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A Study on An Error-Resilient Constant Bit Rate Video Codec (에러 환경에 강한 항등비트율 동영상 부호화기에 관한 연구)

  • 한동원;송진규;김용구;최윤식
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.9B
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    • pp.1721-1730
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    • 1999
  • In this thesis, an error resilient video coding algorithm, under the error-prone environment such as wireless communication, is suggested. The suggested algorithm adapts the Classified VQ method for intra imagers that reduces some load by searching similar vectors. The Duplicate Vector Position Code is proposed for the higher compression efficiency and the robust decoding in error environment. As a result, the bitstream encoded by the proposed method is in a CBR(Constant Bit Rate) preventing from error propagation. The experiment that adds practical error to the encoded bitsrteam shows the error-robustness superior to H.263.

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A Study of Very Low Bit-Rate Color Video Coding Using Adaptive Wavelet Trasform (적응적 웨이블릿 변환을 이용한 저속 비트율 컬러 비디오 코딩에 관한 연구)

  • Kim, Hye-Gyeong;O, Hae-Seok
    • The Transactions of the Korea Information Processing Society
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    • v.7 no.2S
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    • pp.701-710
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    • 2000
  • This paper presents a new method for an efficient coding of very low bit-rate color video based on adaptive wavelet transform. Our approach reveals that the coding process works more efficiently if the quantized wavelet coefficients are preprocessed by a mechanism exploiting the redundancies in the wavelet subband structure. Thus, we focuses optimized activity of coding part, and exhaustive overlapped block motion compensation is utilized to ensure coherency in motion compensated error frames, and raised cosine window is applied. The horizontal and vertical components of motion vectors are encoded separately using adaptive arithmetic coding while significant wavelet coefficients are encoded in bit-plane order using adaptive arithmetic coding. On average the proposed codec exceeds H.263 and ZTE in peak signal-to-noise ratio by as much as 2.07 and 1.38dB at 28 kbits, respectively. Fore entire sequence coding, 3DWCVC method is superior to H.263 and ZTE by 0.35 and 0.71dB on average, respectively.

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A New Fast Variable Length Decoding Method Based on the Probabilistic Distribution of Symbols in a VLC Table (확률분포기반 고속 가변장 복호화 방법)

  • 김은석;채병조;오승준
    • Proceedings of the IEEK Conference
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    • 2001.06d
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    • pp.41-44
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    • 2001
  • Variable length coding (VLC) has been used in many well known standard video coding algorithms such as MPEG and H.26x. However, VLC can not be processed parallelly because of its sequentiality. This sequentiality is a big barrier for implementing a real-time software video codec since parallel schemes can not be applied. In this paper, we propose a new fast VLD (Variable Length Decoding) method based on the probabilistic distribution of symbols in VLC tables used in MPEG as well as H.263 standard codecs. Even though MPEG suggests the table partitioning method, they do not show theoretically why the number of partitioned tables is two or three. We suggest the method for deciding the number of partitioned tables. Applying our scheme to several well-known MPEG-2 test sequences, we can reduce the computational time up to about 10% without any sacrificing video quality

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Adaptive Model-Based Quantization Parameter Decision for Video Rate Control (비디오 비트율 제어를 위한 적응적 모델 기반의 양자화 변수 결정 방법)

  • Kim, Seon-Ki;Ho, Yo-Sung
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.4C
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    • pp.411-417
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    • 2007
  • The rate control is an essential component in video coding to provide better quality under given coding constraints, such as channel capacity, frame rates, etc. In general, source data cannot be described as a single distribution in a video coding, hence it can cause an exhaustive approximation problem. It drops a coding efficiency under weak channel environments, such as mobile communications. In this paper, we design a new quantization parameter decision model that is based on a rate-distortion function of generalized Gaussian distribution. In order to adaptively express various source data distribution, we decide a shape parameter by observing a ratio of samples, which have a small value. For experiment, the proposed algorithm is implemented into H.264/AVC video codec, and its performance is compared with that of MPEG-2 TM5, H.263 TMN8 rate control algorithm. As shown in simulation results, the proposed algorithm provides an improved quality rather than previous algorithms and generates the number of bits closed to the target bits.

Implementation of MPEG-4 Codec for Real-time DVR System Based on PC (PC 기반 실시간 DVR 시스템을 위한 MPEG-4 코덱 구현)

  • Jang Kyung Hyun;Park Ki Tae;Kim Chan Gyu;Hong In Hwa;Kim Jin Kook;Yeo Hun Gu;Moon Young Shik
    • Proceedings of the Korean Information Science Society Conference
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    • 2005.11b
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    • pp.607-609
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    • 2005
  • 본 논문에서는 실시간으로 다채널의 카메라에서 입력되는 영상을 동시에 압축 및 복원할 수 있는 PC 기반의 DVR (Digital Video Recording) 시스템을 위한 MPEG-4 방식의 코덱을 구현하고자 한다. 현재까지의 일반적인 압축 방식은 화상회의 용도의 H.263, VCD 화질의 MPEG-1, DVD급 화질인 MPEG-2가 널리 적용되고 있다. 하지만 이러한 방법들은 저장 데이터의 양이 커서 효율적인 저장이 어렵다. 따라서 본 논문에서는 이러한 문제점을 해결하면서 실시간적으로 다채널 영상 데이터 저장이 가능한 MPEG-4 압축 방식을 적용한 코덱을 제작한다.

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Region-based H.263 Video Codec with Effective Rate Control Algorithm for Low VBR Video (개선된 특징차 비교 방법을 이용한 컷 검출 알고리즘에 관한 연구)

  • 최인호;이대영
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.24 no.9B
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    • pp.1690-1696
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    • 1999
  • Video sequence should be hierachically classified for the content-based retrieval. Cut detection algorithm is an essential process to classify shots. It is generally difficult for cut detection algorithms to detect cut points since a current frame is compared with a previous one, because movement of camera or object made adrupt scene change. We reduce ratio of failed cut detection so that compare the difference between frames of predicted cut point and their neighbors. In this paper, first we get predicted cut point, then we judge that the predicted cut point is true point or not. And we extracted DC images in MPEG video sequence for comparison. As a result of experiments. We confirmed that the cut detection ratio of the proposed algorithm is higher than of any other algorithms.

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Design and Implementation of Visual/Control Communication Protocol for Home Automated Robot Interaction and Control (홈오토메이션을 위한 영상/로봇제어 시스템의 설계와 구현)

  • Cho, Myung-Ji;Kim, Seong-Whan
    • Journal of Internet Computing and Services
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    • v.10 no.6
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    • pp.27-36
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    • 2009
  • PSTN (public switched telephone network) provides voice communication service, whereas IP network provides data oriented service, and we can use IP network for multimedia transport service (e.g. voice over IP service) with economic price. In this paper, we propose RoIP (robot on IP) service scenario, signaling call flow, and implementation to provide home automation and monitoring service for remote site users. In our scheme, we used a extended SIP (session initiation protocol) for signaling protocol between remote site users and home robots. For our bearer transport control, we implemented H.263 video codec over RTP (real-time transport protocol) and additionally DTMF (dual tone multi-frequency) transport for robot actuator control. We implemented our scheme on home robots and experimented with KTF operator network, and it shows good communication quality (average MOS = 9.15) and flexible robot controls.

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