• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권4호
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• pp.1877-1891
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• 2016

In video coding, the goal of rate control (RC) is not only to avoid the undesirable fluctuation in bit allocation, but also to provide a good visual perception. In this paper, a novel frame-level rate control algorithm for High Efficiency Video Coding (HEVC) is proposed. Firstly a model that reveals the relationship between bit per pixel (bpp), the bitrate of the intra frame and the bitrate of the subsequent inter frames in a group of pictures (GOP) is established, based on which the target bitrate of the first intra frame is well estimated. Then a novel frame-level bit allocation algorithm is developed, which provides a robust bit balancing scheme between the intra frame and the inter frames in a GOP to achieve the visual quality smoothness throughout the whole sequence. Our experimental results show that when compared to the RC scheme for HEVC encoder HM-16.0, the proposed algorithm can produce reconstructed frames with more consistent objective video quality. In addition, the objective visual quality of the reconstructed frames can be improved with less bitrate.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(4)
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• pp.25-28
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• 2002

This paper presents variable bit rate(VBR) rate control scheme based on MPEG-4 VM8 rate control scheme. An initial Q searching method provides more accurate bit allocation for the first frame. A frame skipping and RD Model update scheme when coded frame quality is too low or high prevents image quality fluctuation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권1호
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• pp.426-445
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• 2012

Conventional rate control (RC) schemes for H.264 video coding usually regulate output bit rate to match channel bandwidth by adjusting quantization parameter (QP) at fixed full frame rate, and the passive frame skipping to avoid buffer overflow usually occurs when scene changes or high motions exist in video sequences especially at low bit rate, which degrades spatial-temporal quality and causes jerky effect. In this paper, an active content adaptive frame skipping scheme is proposed instead of passive methods, which skips subjectively trivial frames by structural similarity (SSIM) measurement between the original frame and the interpolated frame via motion vector (MV) copy scheme. The saved bits from skipped frames are allocated to coded key ones to enhance their spatial quality, and the skipped frames are well recovered based on MV copy scheme from adjacent key ones at the decoder side to maintain constant frame rate. Experimental results show that the proposed active SSIM-based frameskip scheme acquires better and more consistent spatial-temporal quality both in objective (PSNR) and subjective (SSIM) sense with low complexity compared to classic fixed frame rate control method JVT-G012 and prior objective metric based frameskip method.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송∙미디어공학회 2021년도 하계학술대회
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• pp.52-54
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• 2021

In this paper we propose a method predict whether a video frame contains motion according to the invoking situation of the coding unit mode in HEVC. The motion prediction of video frames is conducive for use in video compression and video data extraction. In the existing technology, motion prediction is usually performed by high complexity computer vision technology. However, we proposed to analyze the motion frame based on HEVC coding unit mode which does not need to use the static background frame. And the prediction accuracy rate of motion frame analysis by our method has exceeded 80%.

• 대한전자공학회논문지SD
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• 제44권6호
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• pp.77-82
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• 2007

기존 H.264 프레임 단위 데이터율 제어는 버퍼 상태와 영상의 복잡도를 효율적으로 사용치 못하여 움직임이 많은 영상에 있어 영상 품질의 변화가 심한 단점이 있다. 특히 인코딩시 설정된 비트율이 낮고 (19.2 kbps 이하) 프레임율이 높아 (30 fps), 영상 프레임당 사용할 수 있는 비트가 작아지면 영상 품질의 변화는 더욱 심해진다. 본 논문에서는 안정된 영상품질과 버퍼상태를 얻기 위해 향상된 H.264 프레임 단위 데이터율 제어 알고리즘을 제안한다. 실험 결과, 제안한 알고리즘은 기존 알고리즘에 비해 향상된 결과를 보였다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2022년도 춘계학술대회
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• pp.650-652
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• 2022

Frame rate up-conversion (FRUC) 알고리즘은 동영상의 프레임율을 향상시키는 영상 보간 기술이다. 이는 고화질 디지털 비디오 시스템에서 저프레임율 동영상으로 인한 화면 떨림이나 흐릿한 움직임 등의 문제를 해소하고 시청자에게 보다 자유롭고 매끄러운 시각 경험을 제공한다. 본 논문에서는 딥러닝 기반의 FRUC 알고리즘을 이용하여 동영상을 압축하는 기술을 제안한다. 제안 방법은 원시 동영상에서 일부 영상을 제외한 후 압축 및 전송하고, 복호화 과정에서 딥러닝 기반의 보간 방법을 이용하여 제외된 영상을 복원함으로써 고효율로 압축한다. 실험에서는 동영상을 1, 3장 단위로 건너뛰며 부호화한 후 복호된 영상과 FRUC 알고리즘에 의해 복원한 영상으로 압축 성능을 평가했다. 1장 및 3장씩 제외했을 때 실험결과는 평균 81.22%, 27.80% BD-rate 감소를 보였다. 3 장씩 제외하는 것이 1장의 제외에 비해 부호화 효율이 낮은 이유는 FRUC 방법으로 복원한 영상의 PSNR이 낮기 때문이다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권11호
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• pp.4170-4188
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• 2014

In this study, we present a denoising algorithm for high-frame-rate videos in an ultra-low illumination environment on the basis of Kalman filtering model and a new motion segmentation scheme. The Kalman filter removes temporal noise from signals by propagating error covariance statistics. Regarded as the process noise for imaging, motion is important in Kalman filtering. We propose a new motion estimation scheme that is suitable for serious noise. This scheme employs the small motion vector characteristic of high-frame-rate videos. Small changing patches are intentionally neglected because distinguishing details from large-scale noise is difficult and unimportant. Finally, a spatial bilateral filter is used to improve denoising capability in the motion area. Experiments are performed on videos with both synthetic and real noises. Results show that the proposed algorithm outperforms other state-of-the-art methods in both peak signal-to-noise ratio objective evaluation and visual quality.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 신호처리소사이어티 추계학술대회 논문집
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• pp.517-520
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• 2003

Commercial video scope use CCD sensor and frame grabber for image capture and A/D interface but application limited by input resolution and high cost. In this paper we introduce portable video scope using CMOS sensor, USB pen and tuner card (low frame grabber) in place of commercial CCD sensor and frame grabber. Our video scope serves as an essential link between advancing commercial technology and research, providing cost effective solutions for educational, engineering and medical applications across an entire spectrum of needs. The software implementation is done using Direct Show in second version after initial trials using First version VFW (video for window), which gave very low frame rate. Our video scope operates on windows 98, ME, XP, 2000. The drawback of our video scope is crossover problem in output images caused due to interpolation, which has to be rectified for more efficient performance.

• ETRI Journal
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• 제38권1호
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• pp.185-194
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• 2016

In this paper, a novel rate control scheme for low delay video coding of High Efficiency Video Coding (HEVC) is proposed. The proposed scheme is developed by considering a new temporal prediction structure of HEVC. In the proposed scheme, the relationship between bit rate and quantization step is exploited firstly to formulate an accurate quadratic rate-quantization (R-Q) model. Secondly, a method of determining the quantization parameters (QPs) for the first frames within a group of pictures is proposed. Thirdly, an accurate frame-level bit allocation method is proposed for HEVC. Finally, based on the proposed R-Q model and the target bit allocated for the frame, the QPs are predicted for coding tree units by using rate-distortion (R-D) optimization. We compare our scheme against that of three other state-of-the-art rate control schemes. Experimental results show that the proposed rate control scheme can increase the Bjøntegaard delta peak signal-to-noise ratio by 0.65 dB and 0.09 dB on average compared with the JCTVC-I0094 and JCTVC-M0036 schemes, respectively, both of which have been implemented in an HEVC test model encoder; furthermore, the proposed scheme achieves a similar R-D performance to Wang's scheme, as well as obtaining the smallest bit rate mismatch error of all the schemes.

• 한국경영과학회지
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• 제24권3호
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• pp.63-72
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• 1999

Recent studies on the Constant Bit Rate and Variable Bit Rate transmissions have mainly focused on the frame by frame encoder rate control based on the quantization parameter. With the existing approaches it is difficult to guarantee a consistent video quality. Also, the rate control overhead is too high for the real-time video sources. In this paper, a channel rate allocation scheme based on the control period is proposed to transmit a real-time video, in which the control period is defined by a pre-specified number of frames or group of pictures. At each control period, video traffic information is collected to determine the channel rate at the next control period. The channel rate is allocated to satisfy various channel rate constraints such that the buffer occupancy at the decoder is maintained at a target level. If the allocated channel rate approaches the level at which the negotiated traffic descriptions may be violated, the encoder rate is decreased through adjusting quantization parameters in the MPEG encoder. In the experimental results, the video quality and the overflow and underflow probabilities at the buffer are compared at different control periods. Experiments show that the video quality and the utilization of network bandwidth resources can be optimized through the suitable selection of the control period.