• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.18 no.7
• /
• pp.1663-1670
• /
• 2014

Recently, lots of research works have been actively focused on the DVC (Distributed Video Coding) techniques which provide a theoretical basis for the implementation of light video encoder. However, most of these studies have showed poorer performances than the conventional standard video coding schemes such as MPEG-1/2, MPEG-4, H.264 etc. In order to overcome the performance limits of the conventional approaches, several channel-divided distributed video coding schemes have been designed in such a way that some information are obtained while generating side information at decoder side and then these are provided to the encoder side, resulting in channel-divided video coding scheme. In this paper, the interpolation scheme by weighted sum of multiple motion-compensated interpolation frames is introduced and a new channel-divided DVC scheme is designed to effectively describe noisy channels based on the motion vector and its matching characteristics. Through several simulations, it is shown that the proposed method performs better than the conventional methods at low bit-rate and keeps the reconstructed visual quality constantly.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.3C
• /
• pp.278-286
• /
• 2010

Motion Compensated Frame Interpolation(MCFI) has been used to reduce motion jerkiness for dynamic scenes and motion blurriness for LCD-panel display as post processing for large screen and full HD(high definition) display. Conventionally, block matching algorithms (BMA) are widely used to do motion estimation for simplicity of implementation. However, there are still several drawbacks. So in this paper, we propose a novel shape-based ME algorithm to increase accuracy and reduce ME computational cost. To increase ME accuracy, we do motion estimation based on shape of moving objects. And only moving areas are included for motion estimation to reduce computational cost. The results show that the computational cost is 25 % lower than full search BMA, while the performance is similar or is better, especially in the fast moving region.

• Journal of Broadcast Engineering
• /
• v.10 no.3
• /
• pp.392-400
• /
• 2005

Highly integrated MPEG-4@SP video compression engine, VideoCore, is proposed for mobile application. The primary components of video compression require the high memory bandwidth since they access the external memory frequently. They include motion estimation, motion compensation, quantization, discrete cosine transform, variable length coding, and so on. The motion estimation processor adopted in VideoCore utilizes the small-size local memories such that the video compression system accesses external memory as less frequently as possible. The entire video compression system is divided into two distinct sub-systems: the integer-unit motion estimation part and the others, and both operate concurrently in a pipelined architecture. Thus the VideoCore enables the real-time high-quality video compression with a relatively low operation frequency.

• Journal of Broadcast Engineering
• /
• v.9 no.3
• /
• pp.236-245
• /
• 2004

A multiview sequence CODEC with view scaiability is proposed in this paper. We define a GGOP (Group of GOP) structure as a basic coding unit to efficiently code multiview sequences. 7he proposed CODEC provides flexible GGOP structures based on the number of views and baseline distances among cameras. Multiview sequences encode consists of disparity estimation/compensation, motion estimation/compensation, residual coding and rate control and generates multiview sequence bitstream. The main bitstream is the same as an MPEG-2 mono-sequence bitstream for MPEG-2 compatibility. The auxiliary bitstream contains information concerning the remaining multiview sequences except for the reference sequences. The proposed CODEC with view scalability provides that a number of view flints are selectively determined at the receiver according to the type of display modes. The proposed multiview sequence CODEC is tested with several multiview sequences to determine its flexibility. compatibility with MPEG-2 and view scaiability. In addition, we subjectively confirm that the decoded bitstreams with view scaiability can be Properly displayed by several types of display modes. including 3D monitors.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.46 no.4
• /
• pp.108-115
• /
• 2009

In this paper, we propose a novel true-motion estimation technique supporting efficient frame error concealment for error-resilient video coding. In general, it is important to accurately obtain the true-motion of objects in video sequences for effectively recovering the corrupted frame due to transmission errors. However, the conventional motion estimation (ME) technique, which minimizes a sum of absolute different (SAD) between pixels of the current block and the motion-compensated block, does not always reflect the true-movement of objects. To solve this problem, we introduce a new metric called an absolute difference of motion vectors (ADMV) which is the distance between motion vectors of the current block and its motion-compensated block. The proposed ME method can prevent unreliable motion vectors by minimizing the weighted combination of SAD and ADMV. In addition, the proposed ME method can significantly improve the performance of error concealment at the decoder since error concealment using the ADMV can effectively recover the missing motion vector without any information of the lost frame. Experimental results show that the proposed method provides similar coding efficiency to the conventional ME method and outperforms the existing error-resilient method.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.12
• /
• pp.150-159
• /
• 2014

The latest video coding standard, HEVC can improve the coding efficiency significantly compared with the H.264/AVC. However the HEVC encoder requires much larger computational complexities. The longer 8-tap interpolation filter of the HEVC which is used in a non-integer motion estimation is one of the reasons and this paper aims to reduce the computational complexities. First of all, three shorter-tap interpolation filters for a motion estimation process are tested rather than the use of a standard interpolation filter. In addition, the fast searching strategies to reduce the number of comparisons for choosing the best non-integer motion vector are proposed. Finally, the interpolation process is selectively applied according to the searching strategy. By combining all of the techniques, the experimental results show that the encoding times can be reduced by 13.6%, 18.5% and 21.1% with the coding efficiency penalties of 0.7%, 1.5% and 2.5%, respectively. For the full-HD video sequences, the coding efficiency penalties are reduced to 0.4%, 1.1% and 1.6% at the same level of the encoding time savings, which shows the effectiveness of the proposed schemes for the high resolution video sequences.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.1C
• /
• pp.69-77
• /
• 2002

Sine digital signal processing for motion pictures requires huge amount of data computation to store, manipulate and transmit, more effective data compression is necessary. Therefore, the ITU-T recommended H.26x as data compression standards for digital motion pictures. The data compression method that eliminates time redundancies by motion estimation using relationship between picture frames has been widely used. Most video conding systems employ block matching algorithm for the motion estimation and compensation, and the algorithm is based on the minimun value of cast functions. Therefore, fast search algorithm rather than full search algorithm is more effective in real time low data rates encodings such as H.26x. In this paper, motion estimation employing the Nearest-Neighbors algorithm is designed to reduce search time using FPGA, coded in VHDL, and simulated and verified using Xilink Foundation.

• Journal of Broadcast Engineering
• /
• v.15 no.3
• /
• pp.426-433
• /
• 2010

The H.264/AVC video coding standard performs inter prediction using variable block sizes to improve coding efficiency. Since we predict not only the motion of homogeneous regions but also the motion of non-homogeneous regions accurately using variable block sizes, we can reduce residual information effectively. However, each motion vector should be transmitted to the decoder. In low bit rate environments, motion vector information takes approximately 40% of the total bitstream. Thus, motion vector competition was proposed to reduce the amount of motion vector information. Since the size of the motion vector difference is reduced by motion vector competition, it requires only a small number of bits for motion vector information. However, we need to send the corresponding index of the best motion vector predictor for decoding. In this paper, we propose a new codeword table based on the phased-in code to encode the index of motion vector predictor efficiently. Experimental results show that the proposed algorithm reduces the average bit rate by 7.24% for similar PSNR values, and it improves the average image quality by 0.36dB at similar bit rates.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.12C
• /
• pp.1232-1239
• /
• 2006

In video standards such as MPEG-1/2/4 and H.264/AVC, motion estimation / compensation(ME/MC) process causes the most encoding complexity of video encoder. The full search method, which is used in general video codecs, exhausts much encoding time because it compares current macroblock with those at all positions within search window for searching a matched block. For the alleviation of this problem, the fast search methods such as TSS, NTSS, DS and HEXBS are exploited at first. Thereafter, DS based MVFAST, PMVFAST, MAS and FAME, which utilize temporal or spacial correlation characteristics of motion vectors, are developed. But there remain the problems of image quality degradation and algorithm complexity increase. In this thesis, the proposed algorithm maximizes search speed and minimizes the degradation of image quality by determining initial search point correctly and using simple one-dimension search patterns considering motion characteristics of each frame.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2011.07a
• /
• pp.287-290
• /
• 2011

분산 동영상 부호화 시스템에서는 복호기에서 움직임 보상 보간 기법을 이용하여 부가정보를 생성한다. 생성된 부가정보와 원 Wyner-Ziv 프레임간의 차이를 채널 부호로 오류 정정하게 되는데 이때 부호기에서는 복호기에서의 오류 정정을 위하여 패리티 비트인 Wyner-Ziv 비트를 복호기로 보내게 되고 복호기에서는 이 Wyner-Ziv 비트를 이용하여 Wyner-Ziv 프레임을 복원하는데 더 많은 Wyner-Ziv 비트가 필요할 경우 피드백 채널을 통해 Wyner-Ziv 비트를 요청하게 된다. 이때 부호기에서 조건부 엔트로피를 구할 수 있다면 이를 이용하여 Wyner-Ziv 비트 전송량을 제어함으로써 피드백 채널을 제거 할 수 있다. 이를 위해 부호기에서도 부가정보를 알아야하는데 복호기에서 사용하는 부가정보 생성 기법은 복잡도가 높기 때문에 사용할 수 없다. 본 논문에서는 부호기에서 간단한 부가정보를 생성하는 방법을 제안하고 분산 동영상 부호화 시스템에 적용하여 피드백 채널을 제거하였을 때의 성능을 분석하였다.