• Title, Summary, Keyword: 비트율 제어

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Macroblock Layer Bit-rates Control Algorithm based on the Linear Source Model (선형 모델 기반 매크로블록 레이어 비트율 제어 기법)

  • Seo Dong-Wan;Choe Yoonsik
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.42 no.6
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    • pp.63-72
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    • 2005
  • In this paper, we propose the bit-rate control algorithm for the block based image compression like H.263, H.263+ or MPEG-4. The proposed algorithm is designed to identify the quantization parameter set through the Lagrangian optimization technique based on the well-known linear source model. We set the Lagrangian cost function with the rates and distortion calculated from the linear source model. We calculate the quantization parameter set using the Vitervi algorithm to solve the Lagrangian optimization problem considering the Dquant method of H.263 and MPEG-4. The proposed algorithm improves the video quality by up to 1.5 dB compared with the TMN8 scheme, and is more effective in the video sources with dynamic activities than the consistent quality approaches.

An Effective of Rate Control for Scene Change in H.264/AVC (장면전환에 효율적인 H.264/AVC 비트율 제어 기법)

  • Son, Nam-Rye;Shin, Yoon-Jeong;Lee, Guee-Sang
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.44 no.1
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    • pp.26-39
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    • 2007
  • In recent years, rate control is an important technique in real time video communication applications using H.264/AVC. Many existing rate control algorithms employ the quadratic rate-distortion model, which is determine the target bits for each P frame. In this paper, 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 an adaptive QP(Quantization Parameter) for improving video distortion, due to high motion and abruptly scene change, which target bit rate and MAD(Mean of Absolute Difference) for current frame considering image complexity variance between previous and current frames. Additionally, it uses frame skip technique to maintain bit stream within a manageable range and protect buffer from overflow or underflow. Experimental results show that the proposed method gives a quality improvement of about 0.5dB when compared to previous rate control algorithm. Also our proposed algorithm encodes the video sequences with less frame skipping compared to the existing rate control for H.264/AVC.

Adaptive Rate Control in Frame-level for Real-time H.264/AVC (실시간 H.264/AVC를 위한 적응적인 프레임 단위 비트율 제어 기법)

  • Kim, Myoung-Jin;Kim, Kyoung-Hwan;Hong, Min-Cheol
    • Journal of Broadcast Engineering
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    • v.13 no.6
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    • pp.804-816
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    • 2008
  • In this paper, we propose an adaptive rate control in frame-level for real-time H.264/AVC. For given QP, bits according to video characteristics, and current frame is close correlation between the adjacent frames. Using the statistical characteristic, we obtain change of occurrence bit about QP to apply the bit amount by QP from the video characteristic and applied in the estimated bit amount of the current frame. In addition, we use weight with QP and occurrence bit amount that is statistical information of encoded previous frames. Simulation results show that the proposed rate control scheme achieves time saving of more than 99% over JM 12.1 rate control algorithm. Nevertheless, PSNR and bit rate were almost same as the performances of JM.

Real-Time Rate Control with Token Bucket for Low Bit Rate Video (토큰 버킷을 이용한 낮은 비트율 비디오의 실시간 비트율 제어)

  • Park, Sang-Hyun;Oh, Won-Geun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.10 no.12
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    • pp.2315-2320
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    • 2006
  • A real-time frame-layer rate control algorithm with a token bucket traffic shaper is proposed for low bit rate video coding. The proposed rate control method uses a non-iterative optimization method for low computational complexity, and performs bit allocation at the frame level to minimize the average distortion over an entire sequence as well as variations in distortion between frames. In order to reduce the quality fluctuation, we use a sliding window scheme which does not require the pre-analysis process. Therefore, the proposed algorithm does not produce time delay from encoding, and is suitable for real-time low-complexity video encoder. Experimental results indicate that the proposed control method provides better visual and PSNR performances than the existing rate control method.

An Efficiency Intra frame coding for low bit-rate video coding (낮은 비트 레이트에서의 동영상 부호화를 위한 I-frame의 고능율 부호화)

  • 조경식;이연문;정차근
    • Proceedings of the IEEK Conference
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    • pp.23-26
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    • 2000
  • 본 논문에서는 정확한 비트 제어가 가능한 I-frame의 효율적인 부호화 방법을 제안한다. 기존 H.263+의 DCT 계수들을 트리 구조로 재구성하여 각 계수에 대해 임베이드 제로트리 부호화 알고리즘을 적용시켜 부호화함으로써 코딩 효율을 향상시킴과 동시에 비트 율의 제어가 용이하도록 한다. 제안 방법의 유효성을 검증하기 위해 표준 동영상에 대한 컴퓨터 모의 실험 결과 제안 방법은 기존의 부호화 방법에 비해 비트 제어가 용이하고 부호화 성능이 개선됨을 확인했다.

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DCT-based Embedded Image Sequence Coding and Bit Allocation Scheme (DCT 기반 임베디드 동영상 부호화 및 최적 비트 배분의 기법)

  • Cheong, Cha-Keon
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.39 no.6
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    • pp.575-584
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    • 2002
  • This paper presents a novel DCT-based embedded zero-tree coding and optimal bit allocation algorithm for image sequence coding. In order to fully utilize the structure of the conventional standard coding algorithm and improve the coding efficiency, motion estimation and compensation(ME/MC)-DCT hybrid coding structure and a modified zero-tree coding algorithm are applied. After the rearrangement DCT coefficients into pyramidal structure according to their significance on the decoded image quality, the modified embedded zero-tree coding is performed on layered coefficients. Moreover, for a given overall bit rates, a new optimal bit control scheme is proposed to achieve the best decoded image quality in the consecutive frames. The rate control scheme can also provide the equal quality of decoded image with the control of bit rate and distortion for each frame. The various simulation results are provided to evaluate the coding performance of the proposed scheme.

Adaptive Rate Control in Unit-level for Real-time H.264/AVC (실시간 H.264/AVC를 위한 적응적인 Unit-level 비트율 제어 기법)

  • Kim, Myoung-Jin;Joo, Won-Hee;Hong, Min-Cheol
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.2C
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    • pp.161-171
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    • 2010
  • In this paper, we propose an adaptive rate control in Unit-level for real-time H.264/AVC. For given QP, bits according to video characteristics, and current frame is close correlation between the adjacent frames. Using the statistical characteristic, we obtain change of occurrence bit about QP to apply the bit amount by QP from the video characteristic and applied in the estimated bit amount of the each unit of current frame. In addition, we use weight with QP and occurrence bit amount that is statistical information of encoded previous frames. Simulation results show that the proposed rate control scheme achieves time saving of more than 99% over JM 12.1 rate control algorithm. Nevertheless, PSNR and bit rate were almost same as the performances of JM.

The Study on the MPEG-2 Video Bitrate Control using GOP Structure (GOP구조를 이용한 MPEG2 비디오 비트율 제어에 관한 연구)

  • Kim, Sang-Dong
    • Proceedings of the Korean Information Science Society Conference
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    • pp.889-891
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    • 2005
  • 디지털 기술과 통신 기술의 발전으로 멀티미디어 컨텐츠가 급격히 증가하고 있다. 이러한 멀티미디어 컨텐츠는 다양한 유무선 서비스 환경에서 실시간 서비스가 가능해야 한다. 그러기 위해서는 멀티미디어 컨텐츠 중 가장 큰 비중을 차지하는 영상 및 오디오 컨텐츠에 대한 압축 및 전송 기술이 요구된다. 현재 여러 분야에서 영상 및 오디오에 대한 압축 표준으로는 MPEG 이 자리잡았다. 그리고 MPEG에 대한 많은 개선 노력이 있었으며 특히 테스트 모델인 TM5를 비롯한 많은 연구에서 벡터 추출이나 양자화를 이용한 방법을 중심으로 비트율을 제어하기 위한 부호화기 모델이 제시되었다. 본 논문에서는 기존의 연구 접근 방식과는 다르게 프레임 유형간의 거리를 이용하여 영상의 특성에 따라 보다 적합한 프레임 구조를 찾아 제안하였다. 즉 영상의 복잡도와 변화도에 따라 영상의 종류를 구분하고 각 종류별 영상에 대한 표준 MPEG 인코딩 화질을 기준으로 삼은 후, GOP구조 내에서 프레임 유형간의 거리를 조정하여 화질을 손상하지 않고 가장 적은 비트율을 보상하는 프레임구조를 실험 및 분석을 통해 찾아 제안하였다.

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An Effective Quality Estimation in Pixel-domain Distributed Video Coding (화소영역 분산비디오 부호화기법에서 효과적인 화질 예측방법)

  • Kim, Jin-soo
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.1024-1026
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    • 2013
  • DVC (Distributed Video Coding) techniques provides a basic theory for the implementation of low-power video encoder. Conventional methods decide the parity bit request at decoder side. These are effective in controlling the bit-rate, but, are not able to control the visual quality. Thus, this paper presents an effective method of estimating visual quality improved by correcting the virtual channel noise for the reconstructed frame. Through several experiments, it is shown that the proposed method are able to estimate effectively the decoded visual quality.

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The First Quantization Parameter Decision Algorithm for the H.264/AVC Encoder (H.264/AVC를 위한 초기 Quantization Parameter 결정 알고리즘)

  • Kwon, Soon-Young;Lee, Sang-Heon;Lee, Dong-Ha
    • Journal of KIISE:Information Networking
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    • v.35 no.3
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    • pp.235-242
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    • 2008
  • To improve video quality and coding efficiency, H.264/AVC adopted an adaptive rate control. But this method has a problem as it cannot predict an accurate quantization parameter(QP) for the first frame. The first QP is decided among four constant values by using encoder input parameters. It does not consider encoding bits, results in significant fluctuation of the image quality and decreases the average quality of the whole coded sequence. In this paper, we propose a new algorithm for the first frame QP decision in the H.264/AVC encoder. The QP is decided by the existing algorithm and the first frame is encoded. According to the encoded bits, the new initial QP is decided. We can predict optimal value because there is a linear relationship between encoded bits and the new initial QP. Next, we re-encode the first frame using the new initial QP. Experimental results show that the proposed algorithm not only achieves better quality than the state of the art algorithm, but also adopts a rate control forthe sequence that was impossible with the existing algorithm. By reducing fluctuation, subjective quality also improved.