• Journal of IKEEE
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• v.3 no.1 s.4
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• pp.93-100
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• 1999

When providing MPEG-2 video service through the ATM network, the degradation of QoS caused by cell losses and cell errors occuring from ATM netwok was assessed by the end-users subjectively and then the relation between CLR, CER and subjective QoS of MPEG-2 video was analyzed. Cell losses and cell errors occuring from the ATM network were generated according to the normal and exponential distribution by NEM module. Video sources were divided into sports and drama by moving feature and were tested. The results of our experiments show that the excellent quality of subjective QoS grade 5 was achieved for a cell loss rate of $2{\times}10^{-7}$ and for a cell error rate of $2{\times}10^{-7}$ and the good quality of subjective QoS grade 4 was achieved for a cell loss rate of $2{\times}10^{-6}$ and for a cell error rate of $2{\times}10^{-6}$ When providing MPEC-2 video service through the ATM network, the results of our experiments will be used as valuable information to determine the network performance objectives for satisfying the QoS required by the end-users and to design the network.

• Journal of Broadcast Engineering
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• v.7 no.4
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• pp.355-361
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• 2002

In this paper, several methods which guarantee the seamless editing when the splicing is applied to the MPEG-2 system streams are described. In the MPEG-2 system standard, it is recommended that the splicing technique is applied in the Transport Stream(TS) domain. However, in view of the video editing, the splicing at an arbitrary picture unit can not be guaranteed. The splicing in the PES domain is only considered in this paper because the PES is one of the MPEG-2 system streams and this result could be directly extended to the video splicing techniques in the TS or PS domain. Thus. the problems that might occur when different two PES streams are spliced and its effects to the video quality are compared and analyzed. Based on this analysis. several methods that can resolve these problems directly in the PES domain are proposed. Consequently, the computer simulation demonstrates that the splicing at a GOP modulo is guaranteed to have good video quality even without considering the state of the PES packet only if the PES_packet_length field of the PES packet header is used.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.8
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• pp.30-38
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• 1999

On providing MPEG-2 video service through the ATM network, it is necessary for network provider to have the ATM QoS objectives in order to guarantee quality of service required by end users at the application layer. In this paper, the degradation of QoS caused by cell losses at application layer is assessed quantitatively by GIQ model considering AAL layer and is evaluated qualitatively by MOS from the viewpoint of the end users in order to analyze the relation between CLR and QoS of MPEG-2 video. From the simulation and empirical results, we know that CLR and $GIQ_{mean}$ for guaranteeing QoS of MOS grade 5(Excellent) are $CLR{\le}4{\times}10^7$ & $GIQ_{mean}{\ge}99.4%$ and those for guaranteeing QoS of MOS grade 4(Good) are $CLR{\le}2{\times}10^6$ & $GIQ_{mean}{\ge}99.705%$.

• Journal of Electrical Engineering and Technology
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• v.9 no.4
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• pp.1411-1417
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• 2014

An MPEG-2 AAC Huffman decoding method based on the fixed length compacted codeword tables, where each codeword can contain multiple number of Huffman codes, was proposed. The proposed method enhances the searching efficiency by finding multiple symbols in a single search, i.e., a direct memory reading of the compacted codeword table. The memory usage is significantly saved by separately handling the Huffman codes that exceed the length of the compacted codewords. The trade-off relation between the computational complexity and the amount of memory usage was analytically derived to find the proper codeword length of the compacted codewords for the design of MPEG-2 AAC decoder. To validate the proposed algorithm, its performance was experimentally evaluated with an implemented MPEG-2 AAC decoder. The results showed that the computational complexity of the proposed method is reduced to 54% of that of the most up-to-date method.

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.4
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• pp.309-318
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• 2004

This paper proposes the H.264-based selective fine granular scalable (FGS) coding scheme that selectively uses the temporal prediction data in the enhancement layer. The base layer of the proposed scheme is basically coded by the H.264 (MPEG-4 Part 10 AVC) visual coding scheme that is the state-of-art in codig efficiency. The enhancement layer is basically coded by the same bitplane-based algorithm of the MPEG-4 (Part 2) fine granular scalable coding scheme. In this paper, we introduce a new algorithm that uses the temproal prediction mechanism inside the enhancement layer and the effective selection mechanism to decide whether the temporally-predicted data would be sent to the decoder or not. Whenever applying the temporal prediction inside the enhancement layer, the temporal redundancies may be effectively reduced, however the drift problem would be severly occurred especially at the low bitrate transmission, due to the mismatch bewteen the encoder's and decoder's reference frame images. Proposed algorithm selectively uses the temporal-prediction data inside the enhancement layer only in case those data could siginificantly reduce the temporal redundancies, to minimize the drift error and thus to improve the overall coding efficiency. Simulation results, based on several test image sequences, show that the proposed scheme has 1∼3 dB higher coding efficiency than the H.264-based FGS coding scheme, even 3∼5 dB higher coding efficiency than the MPEG-4 FGS international standard.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.353-353
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• 2004

• Proceedings of the IEEK Conference
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• 2001.06d
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• pp.97-100
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• 2001

In this paper, We propose a new semiautomatic segmentation method using spatio-temporal similarity. In the proposed scheme, segmentation is performed using gradual region merging and hi-direction at spatio-temporal refinement. Simulation results show the efficiency of the proposed method in semantic object extraction.

• Proceedings of the IEEK Conference
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• 2002.06d
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• pp.37-40
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• 2002

MPEG-4 부호화기는 16×16 픽셀로 이루어진 매크로 블록을 기본 단위로 하는 비디오 객체에 대해 움직임 추정과 움직임 보상을 수행한다. 이때 이전 블록과 현재 블록간의 차이를 8×8 블록으로 BCT하여 압축한다. DCT는 영상 신호의 에너지를 낮은 대역으로 집중시켜 낮은 에너지를 갖는 고주파 성분을 제거하여 정보를 압축하므로 복원된 영상은 블록의 경계선이 표시되는 블록킹 현상이 발생한다. 본 논문에서는 4×4 블록과 8×8 블록을 이용하여 DCT하는 가변 블록 변환 방식을 사용한다. 이는 작은 크기의 블록을 사용하므로 블록내 주파수의 분포를 비교적 좁은 영역으로 변환할 수 있어 블록킹 현상을 줄일 수 있다. 또한 INTRA 프레임의 DCT 과정에서 4개의 DCT 변환 블록중 하나를 이웃하는 블록의 DC 계수와 화소값들을 이용하여 그 값을 예측하여 DCT계수를 결정하고 INTER 프레임에서는 간략화된 정수 DCT의 사용과 작은 블록단위의 작업으로 인한 부호화의 부담을 줄인 다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.2
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• pp.85-92
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• 2009

This paper proposes a full-search block-matching motion estimation circuit with hybrid architecture combining systolic arrays and adder trees for an MPEG-4 encoder. The proposed circuit uses systolic arrays for motion estimation with a small number of clock cycles and adder trees to reduce required circuit resources. The interpolation circuit for 1/2 pixel motion estimation consists of six adders, four subtracters and ten registers. We improved the circuit performance by resource sharing and efficient scheduling techniques. We described the motion estimation circuit for integer and 1/2 pixels at RTL in Verilog HDL. The logic-level circuit synthesized by using 130nm standard cell library contains 218,257 gates and can process 94 D1($720{\times}480$) image frames per second.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.5
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• pp.925-938
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• 2010

Depending on network conditions, a communication network could be overloaded when media are transmitted. Research has been carried out to lessen network overloading, such as by filtering, load distribution, frame dropping, and other methods. Among these methods, one of the most effective is frame dropping, which reduces specified video frames for bandwidth diminution. In frame dropping, B-frames are dropped and then I- and P-frames are dropped, based on the dependency among the frames. This paper proposes a scheme for protecting copyrights by encryption, when frame dropping is applied to reduce the bandwidth of media based on the MPEG-4 file format. We designed two kinds of frame dropping: the first stores and then sends the dropped files and the other drops frames in real time when transmitting. We designed three kinds of encryption methods using the DES algorithm to encrypt MPEG-4 data: macro block encryption in I-VOP, macro block and motion vector encryption in P-VOP, and macro block and motion vector encryption in I-, P-VOP. Based on these three methods, we implemented a digital rights management solution for MPEG-4 data streaming. We compared the results of dropping, encryption, decryption, and the quality of the video sequences to select an optimal method, and found that there was no noticeable difference between the video sequences recovered after frame dropping and the ones recovered without frame dropping. The best performance in the encryption and decryption of frames was obtained when we applied the macro block and motion vector encryption in I-, P-VOP.