• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.4
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• pp.23-30
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• 2004

In MPEG-4 video, Motion Adaptive Intra Refresh (MAIR) encodes a motion area macroblock in intra mode, thereby preventing the error propagation. Motion area is selected by difference of between current macroblock and previous macroblock. An effective implementation of the AIR is to reduce the maximum refresh time and estimate the error prone macroblock. However in the case or the MAIR, unnecessary macroblock can be encoded in intra mode. in this paper, a bitrate AIR is proposed that reduces the maximum refresh time by estimating the error prone macroblock more efficiently.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.2
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• pp.281-288
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• 2011

In this paper, a variable quantization coefficient scanning for macroblock considering the histogram value of previous macroblock's quantization coefficient is proposed. In order to scan a quantization coefficient, the proposed method makes $4{\times}4$ histograms for various prediction modes($16{\times}16$, $16{\times}8$, $8{\times}16$, $8{\times}8$) by adding 1 if the value of quantization coefficient is not 0. After a final mode decision procedure, the $4{\times}4$ histogram of the final mode will be sorted. Then, quantization coefficients in corresponding macroblock of the next frame are scanned using the sorted order. The experimental results show that the proposed scheme reduces the total bits by approximately 0.01~2.25% with similar PSNR performance compared with the previous method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.7C
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• pp.706-715
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• 2005

In this paper, we present a transcoding algorithm for converting an MPEG-2 video bitstream to an H.264 bitstream. The proposed transcoder consists of two parts. One is MPEG2 decoding part and the other is H.264 encoding part Because our algorithm is for transcoding in the spatial domain, MPEG2 decoding part carries out full decoding of MPEG2 bitstream. While, because macroblock type and coded block pattern in MPEG2 are significantly related to macroblock mode in H.264, macroblock mode is selected adaptively according to macroblock type and coded block pattern in H.264 decoding part. Furthermore, motion vector is also used as side-information for 16$\ctimes$16 macroblock mode. Simulation results show that the proposed transcoder yields high reduction of total transcoding time at comparable PSNR.

• Journal of the Institute of Convergence Signal Processing
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• v.7 no.1
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• pp.1-10
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• 2006

To reduce the complexity of video transcoder, transcoding techniques generally use intermediate data such as macroblock types, motion vectors, DCT coefficients, which are extracted from incoming video bitstream. In this Paper, we Propose a new adaptive INTRA update scheme utilizing the importance of each macroblock in a given frame. The importance measure is calculated from the motion vectors which are extracted from the decoding procedure of a incomming video data.'rho ratio of the macroblock to be referred by the next frame is calculated by the motion vectors of the next frame and the macroblocks to be refered higher ratio has more effect on the next frame and the followed frames. The proposed scheme can obtain transcoded bitstreams which has better image quality and more improved resilience against transmission errors.

• ETRI Journal
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• v.32 no.2
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• pp.336-338
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• 2010

A macroblock-level deblocking method is proposed for H.264/AVC, in which blocking artifacts are effectively eliminated in the discrete cosine transform domain at the macroblock encoding stage. Experimental results show that the proposed algorithm outperforms conventional H.264 in terms of coding efficiency, and the bitrate saving is up to 5.7% without reconstruction quality loss.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.3
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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.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.323-326
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• 2005

Several video coding standards, such as MPEG-4 and H.263, have been investigated to reduce the resulting number of bits while pursuing the maximum video quality. The recent video coding standard, H.264, provides higher coding efficiency than previous coding standards by using the mode decision scheme. For mode decision, H.264 chooses the best macroblock mode among the several candidates using Lagrangian cost function which reflects both the rate and the distortion. H.264 employs only one rate-distortion optimization (RDO) model for all macroblocks. Since the characteristics of each macroblock is different, each macroblock should have its own RDO model. In this paper, we propose an adaptive rate-distortion optimization algorithm for H.264. We regulate the Lagrangian multiplier considering the picture type and characteristics of each macroblock.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.2C
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• pp.49-58
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• 2005

For the improvement of coding efficiency, the H.264 standard uses new coding tools. Using these coding tools, H.264 has achieved significant improvements from rate-distortion point of view. The adoption of these tools enables a macroblock in H.264 to have more information, sixteen motion vectors, four reference frames and a macroblock mode. In this paper, we present an efficient temporal error concealment algorithm by using not only motion vectors and reference frames but also macroblock mode of neighbor macroblocks. Our algorithm conceals the macroblock error with variable sizes, $16{\times}16,\;16{\times}8,\;8{\times}16,\;8{\times}8$ depending on the macroblock modes of neighbor macroblocks. Simulation results show that the proposed method increase the objective quality regardless of bit-rate and block error rate.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.6
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• pp.99-105
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• 2014

The performance improvement in MPEG-4 AVC is provided at the expense for higher computational complexity. Most of the complexity is caused by Inter prediction. To improve coding efficiency, some functions are added in H.264/MPEG-4 AVC, such as variable block size motion compensation, multi reference frame and quarter-pel motion compensation. A fast macroblock partition decision method is proposed in this paper. The macroblock size is efficiently determined by using the pixel value difference between encoding and the referred macroblock.

• 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.