• ETRI Journal
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• 제33권4호
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• pp.641-644
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• 2011

In this letter, we propose a novel bitrate control, using both Kalman and FIR filters, based on a Hamiltonian analysis with respect to the amount of bits from each macroblock, in an encoding of a general video codec such as H.264/AVC. Since the proposed bitrate control is based on the simple computation of an optimal control method based on the Hamiltonian analysis, it is not necessary to use additional computation, such as a DCT or quantization, to estimate the bits for bitrate control. As a result, the proposed algorithm can be applied to single-pass encoding and can provide sufficient encoding speed with respect to various applications, even those requiring real-time control.

• IEIE Transactions on Smart Processing and Computing
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• 제1권3호
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• pp.152-160
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• 2012

This paper proposes a frame-level rate control algorithm for low delay video applications to reduce the fluctuations in the bitrate. The proposed algorithm minimizes the bitrate fluctuations in two ways with minimal coding loss. First, the proposed rate control applies R-Q model to all frames including the first frame of every group of pictures (GOP) except for the first one of a sequence. Conventional rate control algorithms do not use any R-Q models for the first frame of each GOP and do not estimate the generated-bit. An unexpected output rate result from the first frame affects the remainder of the pictures in the rate control. Second, a rate-distortion (R-D) cost is calculated regardless of the hierarchical coding structure for low bitrate fluctuations because the hierarchical coding structure controls the output bitrate in rate distortion optimization (RDO) process. The experimental results show that the average variance of per-frame bits with the proposed algorithm can reduce by approximately 33.8% with a delta peak signal-to-noise ratio (PSNR) degradation of 1.4dB for a "low-delay B" coding structure and by approximately 35.7% with a delta-PSNR degradation of 1.3dB for a "low-delay P" coding structure, compared to HM 8.0 rate control.

• 전자공학회논문지S
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• 제35S권3호
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• pp.159-165
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• 1998

In bitrate control of MPEG-2 TM5, $Q_{j}$, N-act, and mquant, of present macroblock are predicted from those of previous macroblock. It results in poor image quality because of abrups change of them. We proposed a method predicting $Q_{j}$, N-act, and mquant, of present macroblock by averaging those parameters of adjacent previous macroblocks. As a results, it shows improved PSNR compared to bitrate control of MPEG-2 TM5.TM5.

• International Journal of Internet, Broadcasting and Communication
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• 제7권2호
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• pp.168-172
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• 2015

In this paper, a balanced bitrate control in transcoding process based on video complexity measure for multi-view system which simultaneously shows multiple channels or video contents in single screen, is proposed. In order to consider the total quality of multiple video streams, the proposed algorithm reduces the complexity of multiple video stream and video quality differences at the same time by controlling bitrates of each stream by weighting when they are stitched for single screen. For the measure of complexity and quality differences between video streams, two different data: histogram of macroblock type and bitrate for each stream are used. The experimental result indicates that proposed algorithm decreases fluctuation of quality difference between videos in the multi-view system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권12호
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• pp.4476-4491
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• 2021

Video service providers tend to face user network problems in the process of transmitting video streams. They strive to provide user with superior video quality in a limited bitrate environment. It is necessary to accurately determine the target bitrate range of the video under different quality requirements. Recently, several schemes have been proposed to meet this requirement. However, they do not take the impact of visual influence into account. In this paper, we propose a new multi-category model to accurately predict the target bitrate range with target visual quality by machine learning. Firstly, a dataset is constructed to generate multi-category models by machine learning. The quality score ladders and the corresponding bitrate-interval categories are defined in the dataset. Secondly, several types of spatial-temporal features related to VMAF evaluation metrics and visual factors are extracted and processed statistically for classification. Finally, bitrate prediction models trained on the dataset by RandomForest classifier can be used to accurately predict the target bitrate of the input videos with target video quality. The classification prediction accuracy of the model reaches 0.705 and the encoded video which is compressed by the bitrate predicted by the model can achieve the target perceptual quality.

• 한국지능정보시스템학회:학술대회논문집
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• 한국지능정보시스템학회 2001년도 The Pacific Aisan Confrence On Intelligent Systems 2001
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• pp.316-321
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• 2001

When the multiple video sources are together transmitted through the channel of fixed bandwidth, the efficiently picture quality method is necessary. This paper presents the picture quality control method to keep the same distortion level among the video sources. We first find a model of distortion and bitrate for the multiplexing system of multiple sources. Then we obtain the bitrate for each source to have same distortion level among the sources by using the approximated model parameters for simple implementation.

• 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.

• 한국정보과학회논문지:소프트웨어및응용
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• 제29권6호
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• pp.355-366
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• 2002

본 논문에서는 2차원 히스토리 풀과 슬라이딩 윈도우를 이용한 MPEG-4 비디오 프레임 기반 비트 생성을 제어 방법을 제안한다. 제안된 방법은 먼저 영상 특성에 따라 코딩 결과를 분류하여 2차원 히스토리 풀에 저장한다. 슬라이딩 윈도우를 이용하여 코딩하려는 영상 프레임의 특성과 비슷한 특성을 갖는 코딩 결과들을 풀에 저장된 결과로부터 수집한다. 마지막으로 수집된 코딩 결과를 이용하여 귀환회귀를 수행하는 방법이다. 제안된 방법을 이용하면 양자화 스텝 결정 시 외삽이 발생되는 경우를 줄여줌으로써 급변하는 영상 특성 변화에 적극적으로 대처할 수 있다. 제안된 비트 생성을 제어 방법은 기존의 MPEG-4 프레임 기반 비트 생성을 제어 방법에 비해 전송선로의 제약을 만족하는 프레임 당 발생된 비트량, 피크 신호 대 잡음비 그리고 프레임 스킵 수의 비교에 있어서 성능이 우수함을 확인하였다.

• 방송공학회논문지
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• 제23권1호
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• pp.104-114
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• 2018

최근 HTTP 기반 비디오 스트리밍 트래픽이 계속해서 증가함에 따라 HTTP 기반 적응적 스트리밍(HTTP-based Adaptive Streaming : HAS) 기술 중 하나인 DASH(Dynamic Adaptive Streaming over HTTP)가 주목받고 있다. 이에 따라 DASH 환경에서 클라이언트에게 높은 QoE(Quality of Experience)를 제공하기 위한 많은 비디오 품질 조절 기법들이 제안되어왔다. 본 논문에서는 뉴로 퍼지 시스템의 구조 중 하나인 ANFIS(Adaptive Network based Fuzzy Inference System)를 이용한 새로운 품질 조절 기법을 제안한다. 제안하는 기법은 ANFIS를 이용하여 클라이언트에게 적절한 세그먼트 비트율을 선택하는 퍼지 파라미터를 찾고, VBR(Variable Bit-Rate) 비디오의 특성을 고려하여 실제 세그먼트의 크기를 이용해 다음 세그먼트 다운로드 시간을 보다 정확하게 예측한다. 그리고 이를 이용해 시변 네트워크에서 적절하게 비디오 품질을 조절한다. NS-3를 이용한 모의실험에서 제안된 기법이 기존 기법들에 비해 높은 평균 세그먼트 비트율과 낮은 비트율 변화 횟수를 보여 클라이언트에게 향상된 QoE를 제공함을 보인다.

• 한국멀티미디어학회논문지
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• 제9권7호
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• pp.818-826
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• 2006

본 논문에서는 특정 부호화율을 가지는 H.264 비트열을 다른 부호화율로 바꾸어 전송하는 비트열변환 방법에서 필요되는 부호화율-양자화변수 사이의 모델 관계식을 규명한다. 그리고 H.264 동영상 부호화된 비트열간 부호화율을 변환하기 위한 새로운 기법을 제안한다. 제안된 비트열 변환기법은 근사화된 부호화율-양자화 계단 크기 사이의 관계식을 사용하여 이전 부호화화면, 이전 슬라이스에서 부호화된 결과로부터 모델변수를 갱신하고, 이로부터 목표되는 양자화 계단 크기를 찾아 재 양자화 이후의 부호화 과정만을 수행하여 목표되는 부호화율로 비트량을 발생시킨다. 따라서, 제안된 방식은 비트열변환에서 복잡한 부호화율 제어를 필요로 하지 않으며, 간단한 구현만으로 목표되는 부호화율로 변환시킨다. 모의실험으로부터 제안된 비트열변환방법이 4가지 다른 특성의 실험영상에 대하여 설정된 비트열로 정확하게 변환됨을 보인다.