• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.12
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• pp.2376-2385
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• 1994

In receiving the digital TV signal, both decoding delay and the channel hopping delay are very critical factors in applications. The intra-slice coding in the MPEG-2 SIMPLE PROFLE of No B-picture is one of the primary methods for short delay time in video decoding. It has the advantage of short decoding delay, but has the drawback of long channel hopping delay time. In this paper, we propose a method to reduce the channel delay with negligible loss in SNR performance. It is shown that dividing pictures into several regions of slices and adding some restriction in motion vector search for inter-frame coding. hence the random acess points are effectively increased. and the channel hopping delay is reduced.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.11
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• pp.2836-2849
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• 1996

Over ATM network, variable bit rate(or VBR) traffic is allowed. Control of VBR traffic is allowed. Control of VBR traffic becomes difficult if it is bursty. VBR video traffic becomes so much bursty during intra frame period that much cell loss would occur when satistical multiplexed in ATM swich. To aviod cellloss, extra communication resources should be allocated, which reduces the capability of an ATM channel. In this paper, we propose two methods which enable a channel limited in resources to serve more VBR MPEG video bit streams. Firstly, we could redue the bitrate fluction of a statiscally multiplexed bundle of VBR video bit streams by reducing the number of intra frames overlapped at the same frame period. This method can be used in ATM switch which controls multiple video sources. Secondary, in two layer enoding, statistical multiplexing gains can be icreased by letting peak bit rate durations of both layers not be overlapped. This results in more smooth traffic. The performance of proposed methods are demonstrated by a proposed calculation method of statistical multiplexing gains(or SMGs.) The proposed SMG is based on both delay and cell loss QoS requirements at the same time.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.425-428
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• 2005

This paper is made up Advanced Image Coding(AIC) that combines algorithms from next generation image coding standard, H.264/MPEG-4 Part 10 advanced video coding(AVC) and still image compression standard, JPEG(Joint Photographic Experts Group). AIC combines intra frame block prediction from H.264 with a JPEG style discrete cosine transform and quantization, followed by Context-based Adaptive Binary Arithmetic Coding(CABAC) as used in H.264. In this paper, we analyzes the efficiency of the AIC algorithm and JPEG and JPEG-2000, and it presents of result.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.5C
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• pp.503-511
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• 2006

H.264 adopts new coding tools such as intra-prediction, loop filter, etc. The adoption of these tools enables an H.264-coded bitstream to have more information compared with previous standards. In this paper we proposed an effective spatial error concealment method for H.264. Among the information included in an H.264-coded bitstream, we use intra-mode for recovering a damaged block. This is because prediction direction in intra-mode is highly correlated to the edge direction of a lost macroblock. We first estimate the edge direction using intra-modes of blocks adjacent to a lost macroblock, and classify the area in a damaged macroblock into the edge and the flat area. And then our method recovers pixel values in the edge area using edge-directed interpolation, and recovers pixel values in the flat area using weighted interpolation. Simulation results show the proposed method yields better video quality than conventional approaches by 0.35 to 5.48 dB.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.12
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• pp.93-101
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• 2007

Small area and low power implementation are important requirements for various multimedia processing hardware, especially for mobile environment. This paper presents a hardware architecture of H.264/AVC Intra Prediction module aiming on small area and low power. A single arithmetic unit was shared and processed sequentially for all mode decisions and computations to predict an image frame. As a result, we could get smaller area and smaller memory size compared to other existing implementations. The proposed architecture was verified using the Altera Excalibur device, and the implemented hardware has been described in Verilog-HDL and synthesized on Samsung STD130 0.18um CMOS Standard Cell Library using Synopsys Design Compiler. The synthesis result was about 11.9K logic gates and 1078 byte internal SRAM and the maximum operating frequency was 107Mhz. It consumes 879,617 clocks to process one QCIF frame, which means it can process 121.5 QCIF$(176\times144)$ frames per second, therefore it shows that it can be used for real time H.264/AVC encoding of various multimedia applications.

• Journal of IKEEE
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• v.13 no.4
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• pp.29-36
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• 2009

The packet loss and the disconnection during handoff are the most critical problems which degrade the video quality in wireless video streaming. To cope with these problems, we propose an efficient video streaming method in this paper, which does not only dynamically adjust the video transmission rate based on the raptor forward error correction (FEC) level, but also minimize the error propagation during handoff. Firstly, the channel bandwidth of the wireless broadband internet, called WiBro, is estimated by analyzing channel parameters including the carrier to interference and noise ratio (CINR) and the handoff. Secondly, the streaming server adjusts the next transmission rate according to the estimated channel bandwidth and the raptor FEC level to avoid packet error. Also, the encoder performs the intra refresh method that inserts an intra frame (I-frame) right after handoff to reduce the error propagation effectively. Experimental results indicate that the proposed method can improve the performance of the video streaming over WiBro network.

• Journal of Korea Multimedia Society
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• v.14 no.7
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• pp.858-865
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• 2011

In order to allow the user to efficiently browse, select, and retrieve a desired video part without having to deal directly with GBytes of compressed data, classification of shot motion characteristic has to be carried out as a preparation for such user interaction. The organization of video information for video database requires segmentation of a video into its constituent shots and their subsequent characterization in terms of content and camera movement in shot. In order to classify shot motion, it is a conventional way to use element of motion vector. However, there is a limit to estimate global camera motion because the way that uses motion vectors only represents local movement. For shot classification in terms of motion information, we propose a new scheme consisting of partial decoding of INTRA pictures and comparing the x, y displacement vector curve between the decoded I-frame and next P-frame in compressed video data.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.689-692
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• 2001

대용량 hard disk를 내장하고 있는 DTV용 PVR(Personal video recorder)에서는 단순히 수신되는 방송 stream을 녹화하고 재생하는 기능 뿐만 아니라 다른 여러 가지의 부가적인 기능들을 지원하는 것이 필요하다. 그 중의 하나가 기존의 아날로그 VCR의 사용자들에게 친숙한 fast-forward play, reverse play, pause 등과 같은 trick mode play기능을 지원하는 것이다. 그러나 MPEG video는 화면간의 상관관계를 이용하여 압축하는 방식을 채택하고 있으므로 재생하고자 하는 frame이 intra frame이 아닌 한 독립적으로 재생할 수가 없어서 trick mode play 기능을 구현하기가 용이하지 않다. 특히 reverse trick mode의 경우에는 original stream에서의 마지막 frame이 먼저 display되어야 하는데 이를 위해 하나의 GOP가 모두 decoding되어야 하므로 더욱 그 구현이 어렵다. 본 논문에서는 reverse trick mode를 구현하기 위한 여러 알고리즘을 소개하고 이에 대한 system 복잡도, 메모리 사용량 성능 등을 분석하고자 한다.

• Proceedings of the KIEE Conference
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• 2005.05a
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• pp.167-169
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• 2005

The occurrence of a single bit error in transmission bitstream leads to serious temporal and spatial errors. Because moving picture coding as MPEG-2 based on block coding algorithm uses variable length coding and motion compensation coding algorithm. In this paper, we propose algorithm to conceal occurred error of I-frames in transmission channel using data of the neighboring blocks in decoder. We divide a damaged macroblock of I-frame into four sub blocks and compose new macroblock using the neighboring blocks for each sub block. We estimate the block with minimum difference value through block matching with previous frame for new macroblocks and replace each estimated block with damaged sub block in the same position. Through simulation results, the proposed algorithm will be applied to a characteristic of moving with effect and shows better performance than conventional error concealment algorithms from visual and PSNR of view.

• Journal of information and communication convergence engineering
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• v.5 no.3
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• pp.269-272
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• 2007

The shortcut shot detection based on MPEG compressed video bitstream is presented in this paper. The detection algorithm is used the video picture frame from MPEG compressed video directly not to be decompressed the original image. For shortcut detection, I and P frame of MPEG video bitstream are classified. The changing scene cuts at I pictures are detected by the decompressed DC image and scene cuts at P picture frame by monitoring the percentage of intra-macroblocks per P picture are detected. Experimental results using test video bitstream QVGA results in average 92% detection rate, searching time is taken around 4.5 times faster in comparison with changing scene shot detection algorithm which is decompressed the compressed bitstream.