• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.99-102
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• 2003

Computing environments of Embedded Systems are different from those of desktop computers so that they have resource constraints such as CPU processing, memory capacity, power, and etc.. Thus, when a desktop S/W is ported into embedded systems, optimization should be seriously considered. In this paper, we investigate several S/W optimization techniques to be considered for porting H.263 encoder into a high performance DSP, TMS320C6711. Through experiments, it is found that optimization techniques employed can make a big performance improvement.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.352-358
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• 2004

This paper is studied the improvement of performance for moving picture encoder using H.263. This is used the new motion vector search algorithm using a relation with neighborhood search point and is applied the integer DCT for the encoder. The integer DCT behaves DCT by the addition operation of the integer using WHT and a integer lifting than conventional DCT that needs the multiplication operation of a floating point number. Therefore, the integer Dn can reduce the operation amount than basis DCT with having an equal PSNR. The new motion vector search algorithm is showed almost similar PSNR as reducing the operation amount than the conventional motion vector search algorithm. To experiment a compatibility of the integer DCT and the conventional DCT, according to result compare case that uses a method only and case that uses the alternate two methods of the integer DCT or the conventional DCT to H.263 encoder and decoder, case that uses the alternate two methods is showed doing not deteriorate PSNR-and being each other compatible visually than case that uses an equal method only.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.656-658
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• 1998

실시간 인터넷 화상회의 시스템을 위한 H.263 동화상 부호화 소프트웨어의 처리속도를 개선하는 기법을 개발하였다. 화상회의 영상의 특성과 H.263 프로토콜의 구조를 분석하여 데이터의 압축률이나 화질에 미치는 영향을 최소화하면서 처리시간을 크게 단축하는 기법을 개발하였다. 처리 속도의 개선을 위해서 움직임 조기 검출 기법을 개발, 적용하므로서 압축률과 화질에 미치는 영향을 최소화하면서 계산량을 크게 줄이도록 하였다.

• Proceedings of the IEEK Conference
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• 2001.09a
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• pp.63-66
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• 2001

본 논문에서는 TI사의 TMS320C6201 DSP를 이용하여 H.263 동영상 부호화기를 실시간 구현하고자 한다. 구현한 부호화기는 QCIF 형식의 영상을 사용하여 ITU-T H.263 권고안의 기본 모드를 따라 주로 C 언어와 intrinsics를 사용하여 구현하였다. 특히, 속도 향상을 위해서 고속 메모리의 사용을 극대화하는데 중점을 두었고, 연산량이 많은 모듈에 대한 최적화와 데이터의 병렬 처리 및 DMA (Direct Memory Access) 전송 등을 고려하여 구현하였다.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10b
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• pp.392-394
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• 1999

PSTN(Public Switch Telephone Network)에서 동영상을 전송하기 위해 H.263이라는 표준이 발표되었다. 저속의 전송률을 가지는 PSTN을 이용해서 영상회의나 영상전화 등을 구현하기 위해서는 기존의 코딩방식으로는 데이터를 전송하는데 문제점이 많았다. 이를 위해서 개발된 것이 H.263이다. H.263은 H.261에 기반을 두고 있으며 .261에 비해서 동일화질을 제공하는데 반정도의 데이터 양으로도 가능하게 해준다. 영상 압축 Encoder는 일반적으로 Decoder에 비하여 영상을 처리하는데 많은 시간이 소요된다. 그러나 VOD등과 같은 실시간으로 압축할 필요가 없는 경우에 대해서는 인코더가 많은 시간을 소비하더라고 큰 문제가 없는 반면에, 영상 회의나 영상 전화 등은 실시간 영상 Encoding, Decoding을 수행해야 한다. 그러기 위해서 고가의 하드웨어를 사용하게 된다. 이와 같은 이유에서 본 연구에서는 H.263을 소프트웨어만으로 Encoding 속도향상을 꾀하고자 하는 것이 이 논문의 목표이다.

• Journal of KIISE:Computer Systems and Theory
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• v.31 no.10
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• pp.543-552
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• 2004

This paper proposes an energy optimization technique for latency and quality constrained video applications. It consists of two key techniques: frame-skipping technique and buffering technique. While buffering increases the slack time utilization at the OS level. frame skipping Increases the slack time itself at the application level, and both enhance the effectiveness of the dynamic voltage scaling technique. We use an H.263 encoder application as a test vehicle to which the proposed technique is applied. Experiments demonstrate that the proposed technique achieves noticeable energy reduction satisfying the given latency and video quality constraints.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.40 no.5
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• pp.417-425
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• 2003

H.264, which is the latest video coding standard of both ITU-T(International Telecommunication Union-Telecommunication standardization sector) and MPEG(Moving Picture Experts Group), adopts new video coding tools such as variable block size motion estimation, multiple reference frames, quarter-pel motion estimation/compensation(ME/MC), 4${\times}$4 Integer DCT(Discrete Cosine Transform), and Rate-Distortion Optimization, etc. These new video coding tools provide good coding of efficiency compared with existing video coding standards as H.263, MPEG-4, etc. However, these new coding tools require the increase of encoder complexity. Therefore, in order to apply H.264 to many real applications, fast algorithms are required for H.264 coding tools. In this paper, when encoder MacroBlock(MB) mode is decided by rate-distortion optimization tool, fast mode decision algorithm by skipping variable block size ME/MC and spatial-predictive coding, which occupies most encoder complexity, is proposed. In terms of computational complexity, the proposed method runs about 4 times as far as JM(Joint Model) 42 encoder of H.264, while the PSNR(peak signal-to-noise ratio)s of the decoded images are maintained.

• Journal of the Korea Computer Industry Society
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• v.5 no.1
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• pp.123-130
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• 2004

In this paper, an advanced error tracking algorithm by using feedback channel was proposed for error resilient transmission. Using this proposed algorithm, the propagation of errors were reduced within the decoded data over bit error prone network. The addresses of corrupted blocks are reported to encoder by decoder. With negative acknowledgments of feedback channel, the encoder can precisely calculate negative acknowledgments and track the propagated errors by examining the backward motion dependency for proper pixel in the current encoding frame. The error-propagation effects can be terminated completely by INTRA refreshing the affected macro-blocks by using proposed error tracking algorithm. By utilizing the selective four-corner error tracking approximation, the error tracking computations of the proposed algorithm is less than that of the algorithm using full pixel without substantial degradation in video quality. The proposed algorithm can track errors rapidly and accurately.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.2072-2075
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• 2003

This paper is studied the high speed processing moving picture encodec to compress and encode a moving picture by real time. This is used the new motion vector search algorithm with smallest search point in H.263 encodec, and is applied the integer DCT for the encodec by converting a moving picture. The integer DCT behaves DCT by the addition operation of the integer using WHT and a integer lifting than conventional DCT that needs the multiplication operation of a floating point number. Therefore, the integer DCT can reduce the operation amount than basis DCT with having an equal PSNR because the multiplication operation of a floating point number does not need.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.285-286
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• 2006

H.264 provide good coding efficiency compared with existing video coding standards as H.263, MPEG-4, etc. However, H.264 require the increase of encoder complexity. In this paper, fast mode decision algorithm by skipping variable block size motion estimation and spatial-predictive coding, which occupies most encoder complexity, is proposed. Experimental results show that the proposed approach can save encoding time to 55% compared with the H.264 standard.