• 제목, 요약, 키워드: 비트율 제어

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Rate Control Algorithm Using Temporal Correlation Between Frames for MPEG-4 and H.264/AVC Video Coding (화면간 상관성을 고려한 MPEG-4 및 H.264/AVC 비트율 제어 알고리즘)

  • Kim Seung-Hwan;Ho Yo-Sung
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • pp.65-70
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    • 2004
  • 본 논문에서는 화면간 상관성을 이용한 최적의 비트 할당 알고리즘을 제안한다 제안된 알고리즘은 기존의 Q2 비트율 제어 알고리즘을 기반으로 하며, 인트라(Intra) 화면에 대한 비트할당과 인터(Inter) 화면에 대한 비트 할당으로 구성된다. 일반적으로 비디오 시퀀스(Sequence)의 각 화면들은 서로 많은 상관성을 가지고 있다. 본 논문에서는 이러한 점을 고려하여, 다른 화면들의 화질에 상대적으로 더 많은 영향을 미칠 수 있는 중요한 화면을 선택하고, 선택된 화면들은 각각의 중요도에 따라 더 많은 비트가 할당되어 화질이 향상된다. 선택된 화면의 화질 향상은 이 화면으로부터 움직임 예측과 움직임 보상을 하는 다른 화면의 화질까지도 향상시킨다. 본 논문에서 제안된 방법은 MPEG-4비디오를 비롯하여 최근에 만들어진 H.264/AVC 부호화 표준에서도 좋은 결과를 보였다.

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A Semantic-based rate control method for motion video coding (동영상 부호화를 위한 의미 기반 Rate control 기법)

  • 이봉호;전경재;곽노윤;강태하;황병원
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.3B
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    • pp.529-540
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    • 2000
  • This is paper presents the semantic based rate-control method which is based on very low bit rate video coding standards H.263 plus, applied on very low bit rate applications. Previous rate control methods control the generated bit rates by setting the optimum quantization parameters per macro block unit on frame. But, in this paper, we added the pre-processing algorithm, semantic region recognition and assignment of priority algorithm, to obtain the subjective quality enhancement. This work aims to improve the subjective quality of skin color region or face by using unimportant background region's bit resources.

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An Accurate Bitrate Control Algorithm for MPEG-2 Video Coding (MPEG-2 비디오 부호화를 위한 정확한 비트율 제어 알고리즘)

  • Lee, Jeong-U;Ho, Yo-Seong
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.38 no.2
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    • pp.218-226
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    • 2001
  • The MPEG-2 Test Model 5 (TM5) algorithm is widely used for bit rate control. In TM5, however, the target number of bits and the number of actual coding bits for each picture do not match well. Therefore, buffer overflow and picture quality degradation may occur at the end of the GOP. In this paper, we propose a new bit rate control algorithm for matching the target and the actual coding bits based on accurate bit allocation. The key idea of the proposed algorithm is to determine quantization Parameters which enable us to generate the number of actual coding bits close to the target number of bits for each picture, while maintaining uniform picture quality and supporting real-time processing. The proposed algorithm exploits the relationship between the number of actual coding bits and the number of estimated bits of the previous macroblock.

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Joint Quality Control of MPEG-2 Video Programs for Digital Broadcasting Services (디지털 방송 서비스를 위한 MPEG-2 비디오 프로그램들의 결합 화질 제어)

  • 홍성훈;김성대
    • Journal of Broadcast Engineering
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    • v.3 no.1
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    • pp.69-84
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    • 1998
  • In digital broadcasting, services such as digital satellite TV, cable TV and digital terrestrial TV, several video programs are compressed by MPEG-2, and then simultaneously transmitted over a conventional CBR (Constant Bit Rate) broadcasting channel. In this paper, we propose a joint quality control scheme to be able to accurately control the relative picture quality among the video programs, which is achieved by simdt;,nL'Ously controlling the video encoders to generate the VBR (Variable Bit Rate) compressed video streams. Our quality control scheme can prevent the video buffer overflow and underflow by total target bit allocation process, and also exactly control the relative picture quality in terms of PSNR (Peak Signal to Noise Ratio) between some programs requiring higher picture quality and others by rate-distortion modification. Furthermore we present a rate-distortion estimation method for MPEG-2 video, which is base of our joint quality control, and verify its performance by experiments. The most attractive features of this estimation method are as follows: 1) computational complexity is low because main operation for the estimation is to calculate the histogram of OCT coefficients into quantizer; 2) estimation results are very accurate enough to be applied to the practical MPEG-2 video coding applications. Simulation results show that the proposed joint quality control scheme accurately controls the relative picture quality among the video progran1s transmitted over a single channel as well as provides more consistent and higher picture quality than independent coding scheme that encodes each program independently.

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TCP-Friendly Rate Control for Vertical Handover over Wireless Heterogeneous Network (무선 이종망 환경에서 Vertical Handover를 위한 TCP-Friendly 비트율 제어)

  • Pyun, Jae-Young
    • Journal of the Institute of Electronics Engineers of Korea CI
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    • v.45 no.2
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    • pp.33-40
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    • 2008
  • Streaming video has become a popular form of transferring media over the wired/wireless network. TCP-friendly rate control (TFRC) is used as a streaming media transport protocol. Using the TCP congestion response function and current network conditions, TFRC adjusts its sending rate to yield the maximum TCP-friendly throughput. Since TFRC was designed for applications that would prefer to maintain a slowly-changing sending rate, it is less responsive to changes in handover between wireless heterogeneous networks such as 3G network, WLAN, and so on. This paper shows a new TFRC method for vertical handover over wireless heterogeneous network. The proposed TFRC method has features of low quality interruption and fast rate adaptation to a new target network. The simulation results show that the proposed one provides better QoS and throughput support than the traditional TFRC scheme during vertical handover.

Adaptive Usage Parameter Control Mechanism using a Variable Token Pool in ATM Networks (ATM망에서 가변 토큰풀을 이용한 적응적 사용 파라메터 제어 메카니즘)

  • Koo, Ja-Gwang;Lee, Hwan-Chung;Kim, Chong-Gun
    • The Transactions of the Korea Information Processing Society
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    • v.4 no.9
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    • pp.2366-2377
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    • 1997
  • An Adaptive Usage Parameter Control(UPC) mechanism using a Variable Token Pool(VTP) which is kind of preventive traffic control in the Asynchronous Transfer Mode(ATM) networks is described. The VTP mechanism can monitor violations of the average bit rate and burst duration as well as peak bit rate for the ON-OFF type traffic. The VTP can vary the token pool size by monitoring burst duration and silence duration for a long term. It also improves the sensitivity against the violation of burst duration and average bit rate and enables to response for the violating traffic situation quickly. The variable token pool size is varied in step size by every burst duration and silence duration. Two important parameters for controlling token pool size are Down_size and Up_size. We compare the performance of LB and JW mechanism with the proposed VTP mechanism by computer simulations. We have known that the proposed method is more effective than the previous mechanisms. It is shown that the cell loss rate of the VTP quite depends on the value of Down_size and Up_size. The two parameters should be decided as a propr value according to traffic situations.

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Model Parameter-based Rate Control Algorithm for Constant Quality Real-Time Video Coding (실시간 부호화를 위한 모델 파라미터 기반 일정 화질 비트율 제어 기법)

  • Jeong, Jin-Woo;Cho, Kyung-Min;Choe, Yoon-Sik
    • Journal of the Institute of Electronics Engineers of Korea SP
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    • v.45 no.3
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    • pp.93-102
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    • 2008
  • In this paper, we propose a rate control algorithm for constant quality real time video coding. To achieve constant quality, previous algorithm exploit mean absolute of difference(MAD) as measure of frame complexity. However, if scene is abruptly changed or if quantization parameter is not constant, encoder produces various output bits with same MAD. Therefore we know that MAD does not appropriately reflect characteristic of frame. To solve this problem, we exploit model parameter as measure of frame complexity. Because model parameter means slope between output bits and MAD, it reflects correctly complexity of frame. And because previous model, R-MAD model, is not considered quantization parameter, as quantization parameter increases or decreases, model parameter of frame also vary. So model parameter obtained using previous model cannot reflect internal characteristic of video. We solve this problem using proposed model, which is considered quantization parameter. Experiment results show that our algorithm provide better performance, in terms of quality smoothness than previous algorithm. Especially, when scene is abruptly changed, our algorithm alleviates quality drop.

Adaptive Macroblock Quantization Method for H.264 Codec (H.264 코덱을 위한 적응적 매크로블록 양자화 방법)

  • Park, Sang-Hyun
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.14 no.5
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    • pp.1193-1200
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    • 2010
  • This paper presents a new adaptive macroblock quantization algorithm which generates the output bits corresponding to the target bit budget. The H.264 standard uses various coding modes and optimization methods to improve the compression performance, which makes it difficult to control the amount of the generated traffic accurately. In the proposed scheme, linear regression analysis is used to analyze the relationship between the bit rate of each macroblock and the quantization parameter and to predict the MAD values. Using the predicted values, the quantization parameter of each macroblock is determined by the Lagrange multiplier method and then modified according to the difference between the bit budget and the generated bits. It is shown by experimental results that the new algorithm can generate output bits accurately corresponding to the target bit rates.

Weight-based Congestion Control Algorithms for H.264/SVC Streaming (H.264/SVC 스트리밍을 위한 가중치 기반 혼잡 제어 알고리즘)

  • Kim, Nam-Yun
    • The Journal of The Institute of Internet, Broadcasting and Communication
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    • v.12 no.2
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    • pp.9-17
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    • 2012
  • Because best-effort Internet provides no guarantees on packet delay and loss, transient network congestion may cause negative effects on H.264/SVC streaming. Thus, the congestion control is required to adjust bit rate by dropping enhancement layers of H.264/SVC streams. This paper differentiates the video streams according to different levels of importance and proposes weighted-based congestion control algorithms to use the rate-distortion characteristics of streams. To maximize the weighted sum of PSNR values of all streams on a bandwidth-constrained node, this paper proposes WNS(Weighted Near-Sighted) and WFS(Weighted Far-Sighted) algorithms to control the number of enhancement layers of streams. Through simulation, this paper shows that weighted-based congestion control algorithm can efficiently adapt streams to network conditions and analyzes the characteristics of congestion control algorithms.