• The Transactions of the Korean Institute of Electrical Engineers P
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• v.52 no.2
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• pp.85-90
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• 2003

This paper has presented the efficient implementation of MPEG-4 simple profile video decoder, which is used as video compression standard in mobile video communication. We have used the ARM9 processor in implementing this MPEG-4 simple profile, which requires much processing power and low power implementation. At first we implemented with C-language under the PC environment with ADS(ARM Developer Suite) environment, and then we have tried to reduce a clock cycle for a power consumption optimization through conversion an assembly language for C-code partly. We have verified the processor is operated at 22.47MHz operation after optimization, but 148MHz before optimization.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.47 no.3
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• pp.87-95
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• 2010

Portable multi-media products which can service the highest audio-quality by using lossless audio codec has been released and the international lossless codecs, MPEG-4 audio lossless coding(ALS) and MPEG-4 scalable lossless coding(SLS), were standardized by MPEG in 2006. The simple profile of MPEG-4 ALS, it supports up to stereo, was defined by MPEG in 2009. The lossless audio codec should have low-complexity in stereo to be widely used in portable multi-media products. But the previous researches of MPEG-4 ALS have focused on an improvement of compression ratio, a complexity reduction in multi-channels coding, and a selection of linear prediction coefficients(LPCs) order. In this paper, the complexity and compression ratio of MPEG-4 ALS encoder is analyzed in simple profile of MPEG-4 ALS, the method to reduce a complexity of MPEG-4 ALS encoder is proposed. Based on an analysis of complexity of MPEG-4 ALS encoder, the complexity of short-term prediction filter of MPEG-4 ALS encoder is reduced by using the low-complexity filter that is proposed in previous research to reduce the complexity of MPEG-4 ALS decoder. Also, we propose a joint coding decision method, it reduces the complexity and keeps the compression ratio of MPEG-4 ALS encoder. In proposed method, the operation of joint coding is decided based on the relation between cross-correlation of residual and compression ratio of joint coding. The performance of MPEG-4 ALS encoder that has the method and low-complexity filter is evaluated by using the MPEG-4 ALS conformance test file and normal music files. The complexity of MPEG-4 ALS encoder is reduced by about 24% by comparing with MPEG-4 ALS reference encoder, while the compression ratio by the proposed method is comparable to MPEG-4 ALS reference encoder.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.5
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• pp.203-216
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• 2004

Recent advances in video coding technology have resulted in rapid growth of application in mobile communication, With this explosive growth reliable transmission and error resilient technique become increasingly necessary to offer high quality multimedia service. In this paper, we present the result of our investigation on the error resilient performance evaluation of the MPEG-4 simple profile under the H.324/M and the H.264/AVC baseline under the IP packet networks. Especially, we have tested error resilient tools of MPEG-4 simple profile such as resynchronization marker insertion, data partitioning, and of H.264/AVC baseline such as the flexible macroblock ordering (FMO) scheme. The objective quality of decoded video is measured in terms of rate and PSNR under various random bit and burst error conditions.

• Journal of IKEEE
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• v.5 no.2 s.9
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• pp.221-231
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• 2001

In this paper, we propose an efficient requantization method for INTRA frames in heterogeneous transcoding from MPEG-1 to MPEG-4 simple profile. The quantizer for MPEG-1 INTRA MB usually uses a quantization weighting matrix while the quantizer for MPEG-4 simple profile doesn't. As a result, the quantization step sizes of the two quantizers may not be the same even for the same quantization parameter. Due to this mismatch in the quantization step site, the transcoded MPEG-4 sequence suffers from serious quality degradation and the number of bits produced by transcoding increases from the original MPEG-1 video sequence. To solve these problems, we propose an efficient method to find a near-optimum reconstruction level in the transcoder. We also present a PDF (probability distribution function) estimation method for the original DCT coefficients of MPEG-1 video sequence, which is required for the proposed requantization. Experimental results show that the proposed method gives $0.3{\sim}0.6dB$ improvement in PSNR over the conventional method, even at the reduced bit-rate about $5{\sim}7%$ from the conventional method.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2004.11a
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• pp.53-56
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• 2004

H.264/AVC (baseline profile)은 MPEG-4 (simple profile)에 비하여 약 2배정도 향상된 압축 성능을 나타내는 것으로 알려져, DMB 방송, DVD 등에 사용될 예정이며, 다양한 멀티미디어 서비스에 사용될 차세대 비디오 압축 표준으로 인정받고 있다 하지만, 부호기의 복잡도는 MPEG-4 simple profile에 비하여 16배정도 높아져서, 실시간을 요구하는 서비스, 또는 임베디드 환경을 갖는 서비스에 사용하는데 심각한 제약을 갖는다. 따라서, 기존의 표준 코덱들을 대체하여 다양한 통신 환경에서 향상된 화질의 비디오 서비스를 제공하기 위해서는 코덱의 복잡도 개선이 매우 중요하다. 본 논문은 H.264/AVC 비디오 코덱을 임베디드 환경을 갖는 통신 서비스에 적용하기 위하여 코덱의 복잡도를 개선하기 위한 방법을 제시한다

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1288-1291
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• 2002

In this paper, we present a design of mpeg-4 video codec chip to reduce the power consumption using frame level clock gating and motion estimation skip scheme. It performs 30 grames/s of codec (encoding and decoding) mode with quarter-common intermediate format(QCIF) at 27MHz. A novel low-power techniques were implemented in architectural level, which is 35% of the power dissipation for a conventional CMOS design. This chip performs MPEG-4 Simple Profile Level 2(Simple@L2) and H.263 base mode. Its contains 388,885 gates, 662k bits memory, and the chip size was 9.7 mm x 9.7 mm which was fabricated using 0.35 micron 3-layers metal CMOS technology.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.5
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• pp.275-282
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• 2004

In this paper, a transcoding method that transforms MPEG-4 video bitstream coded in 30 Hz frame rate into H.264 video bitstream of 15 Hz frame rate is proposed. The block modes and motion vectors in MPEG-4 is utilized in H.264 for block mode conversion and motion vector (MV) interpolation methods. The proposed three types of MV interpolation method can be used without performing full motion estimation in H.264. The proposed transcoder reduces computation amount for full motion estimation in H.264 and provides good quality of H.264 video at low bitrates. In experimental results, the proposed methods achieves 3.2-4 times improvement in computational complexity compared to the cascaded pixel-domain transcoding, while the PSNR (peak signal to noise ratio) is degraded with 0.2-0.9dB depending on video sizes.

• Journal of Broadcast Engineering
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• v.9 no.4 s.25
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• pp.434-445
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• 2004

Motion Estimation is an essential module in video encoders based on international standards such as H.263 and MPEG. Many fast motion estimation algorithms have been proposed in order to reduce the computational complexity of a well-known full search algorithms(FS). However, these fast algorithms can not work efficiently in DSP processors recently developed for video processing. To solve for this. we propose an efficient motion estimation scheme optimized in the DSP processor like Philips TM1300. A motion vector predictor is pre-estimated and a small search range is chosen in the proposed scheme using strong motion vector correlation between a current macro block (MB) and its neighboring MB's to reduce computation time. An MPEG-4 SP@L3(Simple Profile at Level 3) encoding system is implemented in Philips TM1300 to verify the effectiveness of the proposed method. In that processor, we can achieve better performance using our method than other conventional ones while keeping visual quality as good as that of the FS.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2003.11a
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• pp.143-146
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• 2003

최근 디지털 당송과 이동통신 단말기의 대중화가 이루어짐에 따라 고화질 고해상도의 멀티미디어 컨텐츠의 이동통신 단말기에서의 재생 서비스에 대한 수요가 증가하고 있다 이동통신 단말기에서 멀티미디어 컨텐츠 재생 서비스를 제공하기 위해서는 디지털 방송 컨텐츠를 단말기에 적합한 컨텐츠로 변환할 필요가 있다. 본 논문은 디지털 방송 규격인 MPEG-2 컨텐츠를 이동통신 단말기에서 지원하는 MPEG-4 SP(Simple Profile) 컨텐츠로 실시간으로 변환하는 트랜스 코더에 대한 설계와 구현 기술을 제안한다. 구현된 트래스코더는 화질 유지와 계산량 감소를 위한 적응적 움직임벡터 재구성, 매크로블록 모드 선택, 그리고 움직임벡터 scaling 등의 알고리즘을 포함하고, 인텔사에서 제공하는 SIMD(Single Instruction Multiple Data) 명령어를 이용하여 최적화되었다. 트랜스코더는 30fps, 8Mbps, $720\times480$ 해상도의 멀티미디어 컨텐츠를 다양한 비트율의 30fps, $352\times240$ 해상도의 MPEG-4 컨텐츠로 실시간 변환할 수 있다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.6C
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• pp.459-470
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• 2008

In this paper, we propose a fast ME (motion estimation) algorithm for MPEG-4 to H.264 Transcoder. Whereas 2 modes ($8{\times}8$, $16{\times}16$) are used for ME in MPEG-4 simple profile, ME using 7 modes is supported for further enhanced coding efficiency in H.264. The transcoding speed is affected dominantly by the computational complexity of encoder part in transcoder, where ME module of H.264 encoder has high complexity due to using 7 modes. In order to increase the speed of transcoding between MPEG-4 and H.264, we use 3 PMVs (predicted motion vectors) and the mode information of MBs (macroblocks) provided from the decoder part of transcoder. Since the proposed 3 PMVs are very close to an optimal motion vector, and we consider only some restricted modes according to the MB information transferred from decoder part, the proposed scheme can speed up the transcoding procedure without loss of image quality. We show experimental results which demonstrate the effectiveness of the proposed algorithm, where performance of our scheme is compared with that of the conventional fast algorithm for H.264.