• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.4
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• pp.891-898
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• 2014

The DVC (Distributed Video Coding) provides a theoretical basis for the implementation of light video encoder. Conventionally, lots of studies have been focused on the codec scheme of Stanford University that has a feedback channel to control the bit rate finely. However, the codec scheme can not evaluate the qualities of the frames reconstructed by the received parity bits at the decoder side. This paper presents an efficient method of estimating distortion by correcting the virtual channel noises in side information and then facilitating the measurements of the visual qualities. Through several simulations, it is shown that the proposed method is very efficient in estimating the visual qualities of the reconstructed WZ frames.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.2
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• pp.383-393
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• 2010

DVC (Distributed Video Coding) allows us to explore the video statistics at the decoder side, resulting in a less complex encoder and more complex decoder. In this approach, it is important to generate a good prediction to the current Wyner-Ziv frame, called side information, which plays a crucial role in the overall performance of a DVC system. Conventional MCFI (motion compensated frame interpolation) techniques, which explore temporal correlations between neighbor frames of the current frame, preform the block-based or object-based motion estimation, but, they do not include the basis frame for the Wyner-Ziv frame. This paper proposes an efficient way to get better side information, by finding the average frame between neighbor frames and by comparing adaptively the candidate blocks. Through computer simulations, it is shown that the proposed method can improve the performance up to 0.4dB and provide better subjective and objective visual qualities in Wyner-Ziv CODEC.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.161-162
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• 2011

Recently, many research works are focusing on DVC (Distributed Video Coding) system for low complexity encoder. However the feedback channel-based parity bit control is a major cause of the high decoding time latency. Spatial and temporal correlation is high in video and, therefore, the statistical property can be applied for the parity bit request of LDPCA frame. By introducing frame adaptive parity bit request estimation method, this paper proposes a new method for reducing the decoding time latency. Through computer simulations, it is shown that the proposed method achieves about 80% of complexity reduction, compared to the conventional no-estimation method.

• The Journal of the Korea Contents Association
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• v.12 no.12
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• pp.14-24
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• 2012

DVC (Distributed Video Coding) techniques need feedback channel for parity bit control to achieve the good RD performances, however, this causes the DVC system to have high decoding latency. In order to implement in real time environments and to accelerate commercializations, many research works have been focusing on the development of fast video decoding algorithm. As one of the real time implementations, this paper deals with a novel DVC scheme suitable for some application areas where source statistics such as motion information can be provided to the encoder side from the decoder side. That is, this paper propose a fast distributed video decoding scheme to improve the decoding speed by using the feedback of motion information derived in SI generation. Through computer simulations, it is shown that the proposed method outperforms the conventional fast DVC decoding schemes.

• The KIPS Transactions:PartC
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• v.19C no.2
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• pp.145-148
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• 2012

In a distributed streaming system using an advanced coding scheme that encodes a video into multiple substreams, the capacity of the system depends on the amount of contribution of participating peers. Thus, an incentive mechanism for peers to contribute voluntarily is needed to increase system capacity. In addition, since peers are not only a provider but also a consumer in the system (i.e. prosumer), the overall capacity of the system must be allocated fairly among the peers while it must be allocated in a way that can maximize the net quality of experience of peers to increase system efficiency. In this paper, we propose a substream allocation method to solve the problems taking an optimization approach. Unlike the other optimization approaches, the proposed method is verified quantitatively in a simulation study that it can use the capacity of video streaming system efficiently while allocating fair amount of substreams among peers because it considers explicitly the prosumer characteristics of peers.

• Journal of Internet Technology
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• v.21 no.1
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• pp.203-219
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• 2020

Compressed video sensing (CVS) is one of the 5G application of compressed sensing (CS) to video coding. Block-based residual reconstruction is used in CVS to explore temporal redundancy in videos. However, most current studies on CVS focus on random measurements without quantization, and thus they are not suitable for practical applications. In this study, an efficient ratecontrol scheme combining measurement rate and quantization for residual reconstruction in CVS is proposed. The quantization effects on CS measurements and recovery for video signals are first analyzed. Based on this, a mathematical relationship between quantitative distortion (QD), sampling rate (SR), and the quantization parameter (QP) is derived. Moreover, a novel distortion model that exhibits the relationship between QD, SR, and QP is presented, if statistical independency between the QD and the CS reconstruction distortion is assumed. Then, using this model, a rate-distortion (RD) optimized rate allocation algorithm is proposed, whereby it is possible to derive the values of SR and QP that maximize visual quality according to the available channel bandwidth.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.11a
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• pp.138-139
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• 2010

본 논문은 저복잡도 비디오 부/복호화를 위한 엔트로피 부호화 기반의 분산 비디오 코딩 방법을 제안한다. 제안하는 엔트로피 부호화 기반의 분산 비디오 코딩은 복호기의 복잡도를 줄이기 위하여 기존의 분산 비디오 코딩에서 사용하는 채널코딩을 이용하는 것이 아니라 엔트로피 코딩을 이용하여 부호화를 수행한다. 제안하는 방법에서 복호가는 움집임 추정을 수행하고 그 결과인 움직임 백터를 부호기로 전송하며, 부호기는 전송받은 움직임 백터를 초기 움직임 백터로 하여 움직임 백터 값의 갱신을 수행한다. 제안한 방법의 성능을 평가하기 위하여 기존의 분산 비디오 코딩 방법과 복호기 복잡도를 비교한 결과 99%의 복잡도 감소가 있었고, H.264/AVC의 All Intra 방법과 비교하여 20.3%의 비트율 감소가 있었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.2C
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• pp.172-181
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• 2010

In this paper, we propose an adaptive block quantization method. The propose method perfrect reconstructs side information without high complexity in the encoder side, as transmitting motion vectors from a decoder to an encoder side. Also, at the encoder side, residual signals between reconstructed side information and original frame are adaptively quantized to minimize parity bits to be transmitted to the decoder. The proposed method can effectively allocate bits based on bit error rate of side information. Also, we can achieved bit-saving by transmission of parity bits based on the error correction ability of the LDPC channel decoder, because we can know bit error rate and positions of error bit in encoder side. Experimental results show that the proposed algorithm achieves bit-saving by around 66% and delay of feedback channel, compared with the convntional algorithm.

• Journal of Broadcast Engineering
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• v.15 no.1
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• pp.52-62
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• 2010

Recently, DVC (Distributed Video Coding) is attracting a lot of research works since this enables us to implement a light-weight video encoder by distributing the high complex tasks such as motion estimation into the decoder side. In order to improve the coding efficiency of the DVC, the existing works have been focused on the efficient generation of side information (SI) or the virtual channel modeling which can describe the statistical channel noise well. But, in order to improve the overall performance, this paper proposes a new scheme that can be implemented with simple bit operations without introducing complex operation. That is, the performance of the proposed scheme is enhanced by using the fact that the Wyner-Ziv (WZ) frame and side information are highly correlated, and by reducing the effect of virtual channel noise which tends to be clustered in some regions. For this aim, this paper proposes an efficient pixel-domain WZ (PDWZ) CODEC which effectively exploits the statistical redundancy by using the code conversion and Gray code, and then reduces the channel noise by using the bit interleaver. Through computer simulations, it is shown that the proposed scheme can improve the performance up to 0.5 dB in objective visual quality.

• Journal of Broadcast Engineering
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• v.16 no.1
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• pp.108-122
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• 2011

In this paper, a transcoding method with low computational complexity and high coding efficiency is proposed to transcode distributed video coding (DVC) bitstreams to H.264/AVC ones. For the proposed high-performance transcoding with low complexity, not only Wyner-Ziv frames but also key frames can be transcoded with motion vectors estimated in generation of side information. As a motion vector is estimated from a key frame to a prior key frame for side information generation, the motion vector can be used to encode the intra key frame as a predicted frame. Motion estimation is performed with two predicted motion vectors. One is the motion vector from side information generation and the other is median of motion vectors of neighboring blocks. The proposed method selects the best motion vector between two motion vectors based on rate-distortion optimization. Coding efficiency can be improved with a small size of search range, because a motion vector estimated in side information generation is used as an initial motion vector for transcoding. In the experimental results, complexity of transcoder is reduced about 12% and bitrate performance increases about 28.7%.