• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.800-803
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• 2005

모바일 단말 기반 동영상 서비스 기술에 관한 연구는 최근에 이르기까지 활발히 수행되고 있으며, 인터넷 기반에서 상용화가 가능한 기술 분야를 모바일에 응용하는 시도가 계속되고 있다. 모바일 단말 기반 영상서비스와 관련하여 최신형 모바일 단말에서는 관련기술을 하드웨어적으로 구현하거나 독자적 동영상 압축기술을 적용한 소프트웨어적 구현을 통하여 동영상 서비스를 제공하고 있다. 그러나 상당한 비율을 점하고 있는 기존 모바일 단말에서는 이들 하드웨어 칩이 없거나 추가적으로 애드온(add-on) 할 수 있는 표준적인 방법이 정해지지 않아 최신의 동영상 서비스 기술을 제공받을 수 없다. 따라서 시시각각으로 변화하는 모바일 동영상 서비스 환경에 적극적으로 대처하기 위해서는 소프트웨어적 해결방안이 필수적이라는 인식이 대두되고 있다. 본 연구에서는 모바일 단말에서 소프트웨어 디코더를 이용하여 기존 단말에서 뿐만 아니라 향후 최신단말에서도 적극적으로 대처하기 위하여 H.264/AVC 기반 소프트웨어 디코더를 모바일 단말에 적용하는 방안에 대하여 제안한다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.12
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• pp.58-65
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• 2011

This paper presents an ASIP (Application-specific Instruction Processor) for motion estimation that employs specific IME instructions and its programmable and reconfigurable hardware architecture for various video codecs, such as H.264/AVC, MPEG4, etc. With the proposed specific instructions and variable point 2D SAD hardware accelerator, it can handle the real-time processing requirement of High Definition (HD) video. With the SAD unit and its parallel operations using pattern information, the proposed IME instructions support not only full search algorithms but also other fast search algorithms. The hardware size is 25.5K gates for each Processing Element Group (PEG) which has 128 SAD Processor Elements (PEs). The proposed ASIP has been verified by the Synopsys Processor Designer and implemented by the Design Compiler using the IBM 90nm process technology. The hardware size is 453K gates for the IME unit and the operating frequency is 188MHz for 1080p@30 frame in real time. The proposed ASIP can reduce the hardware size about 26% and the number of operation cycles about 18%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.5C
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• pp.371-381
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• 2005

In this paper, we propose an advanced hardware architecture for the CAVLC entropy encoder/decoder engine for real time video compression. The CAVLC (Context-based Adaptive Variable Length Coding) is a lossless compression method in H.264/AVC and it has high compression efficiency but has computational complexity. The reference memory size is optimized using partitioned storing method and memory reuse method which are based on partiality of memory referencing. We choose the hardware architecture which has the most suitable one in several encoder/decoder architectures for the mobile devices and improve its performance using parallel processing. The proposed architecture has been verified by ARM-interfaced emulation board using Altera Excalibur and also synthesized on Samsung 0.18 um CMOS technology. The synthesis result shows that the encoder can process about 300 CIF frames/s at 150MHz and the decoder can process about 250 CIF frames/s at 140Mhz. The hardware architectures are being used as core modules when implementing a complete H.264/AVC video encoder/decoder chip for real-time multimedia application.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.11
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• pp.71-76
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• 2008

H.264(or MPEG-4/AVC pt.10) is a high performance video coding standard, and is widely used. Variable length code (VLC) of the H.264 standard compresses data using the statistical distribution of values. A decoder parses the compressed bit stream and searches decoded values in lookup tables, and the decoding process is not easy to implement by hardware. We propose an architecture of variable length decoder(VLD) for the H.264 baseline profile(BP) L4. The CAVLD decodes syntax elements using the combination of arithmetic units and lookup tables for the optimized hardware architecture. A barral shifter and a first 1's detector parse NAL bit stream, and are shared by Exp-Golomb decoder and CAVLD. A FIFO memory between CAVLD and the reorder unit and a buffer at the output of the reorder unit eliminate the bottleneck of data stream. The proposed VLD is designed using Verilog-HDL and is implemented using an FPGA. The synthesis result using a 0.18um standard CMOS technology shows that the gate count is 22,604 and the decoder can process HD($1920{\times}1080$) video at 120MHz.

• Journal of Broadcast Engineering
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• v.17 no.4
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• pp.640-658
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• 2012

One of the existing terrestrial multi-channel DTV service frameworks, called KoreaView, provides four programs, composed of MPEG-2 based one HD video and H.264/AVC based three SD videos within one single 6MHz frequency bandwidth. However the additional 3 SD videos can not provide enough quality due to its reduced spatial resolution and low target bitrates. In this paper, we propose a framework, which is called a terrestrial multi-channel high quality hybrid DTV service, to overcome such a weakness of KoreaView services. In the proposed framework, the three additional SD videos are encoded based on an H.264/SVC Spatial Base layer, which is compliant with H.264/AVC, and are delivered via broadcasting networks. On the other hand, and the corresponding three additional HD videos are encoded based on an H.264/SVC Spatial Enhancement layer, which are transmitted over broadband networks such as Internet, thus allowing the three additional videos for users with better quality of experience. In order to verify the effectiveness of the proposed framework, various experimental results are provided for real video contents being used for DTV services. First, the experimental results show that, when the SD sequences are encoded by the H.264/SVC Spatial Base layer at a target bitrate of 1.5Mbps, the resulting PSNR values are ranged from 34.5dB to 42.9dB, which is a sufficient level of service quality. Also it is noted that 690kbps-8,200kbps are needed for the HD test sequences when they are encoded in the H.264/SVC Spatial Enhancement layer at similar PSNR values for the same HD sequences encoded by MPEG-2 at a target bitrate of 12 Mbps.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.193-195
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• 2009

Bluetooth is a popluar wireless data transmission method with low power consumption. In this paper, we present a open source based player of video stream encoded by H.264 codec, which is transmitted via Bluetooth. An open source JM is used for H.264 decoding and modified for reading H.264 encoded data via Bluetooth. For display of decoded video data, SDL was utilized.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.12C
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• pp.1669-1676
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• 2004

In H.264, 7 modes {16${\times}$16, 16${\times}$8, 8${\times}$16, 8${\times}$8, 8${\times}$4, 4${\times}$8, 4${\times}$4) are used to enhance the coding efficiency. The motion vector estimation with 7 modes may require huge computing time. In this paper, to speed up the motion vector estimation procedure while the high image quality remains, we propose a motion vector refinement scheme using the temporary motion vector generated with little computation. The proposed estimation process consists of three phases: Mode decision for a 16${\times}$16 macroblock, Composing a temporary motion vector, Refinement of the temporary motion vector. We demonstrate the effectiveness of the proposed method by computer simulation. In the results, the encoding time consumed by the proposed scheme has been reduced significantly while the encoded video quality remains unchanged.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.2C
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• pp.181-188
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• 2007

This paper proposed a watermark embedding/extracting method using CABAC(Context-based Adaptive Binary Arithmetic Coding) which is the entropy encoder for the main profile of MPEG-4 Part 10 H.264/AVC. This algorithm selects the blocks and the coefficients in a block on the bases of the contexts extracted from the relationship to the adjacent blocks and coefficients. A watermark bit is embedded without any modification of coefficient or with replacing the LSB(Least Significant Bit) of the coefficient with a watermark bit by considering both the absolute value of the selected coefficient and the watermark bit. Therefore, it makes it hard for an attacker to find out the watermarked locations. By selecting a few coefficients near the DC coefficient according to the contexts, this algorithm satisfies the robustness requirement. From the results from experiments with various kinds and various strengths of attacks the maximum error ratio of the extracted watermark was 5.02% in maximum, which makes certain that the proposed algorithm has very high level of robustness. Because it embeds the watermark during the context modeling and binarization process of CABAC, the additional amount of calculation for locating and selecting the coefficients to embed watermark is very small. Consequently, it is highly expected that it is very useful in the application area that the video must be compressed right after acquisition.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.146-147
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• 2009

본 논문에서는 단일 프레임 내에서 인접한 매크로 블록 간의 움직임의 유사도를 이용한 개선된 PDE 알고리즘을 제안한다. 제안한 방법은 기존의 방법보다 불필요한 후보 블록을 효율적으로 제거하기 위하여 인접한 매크로블록간의 유사도를 고려하여 인접 4개의 매크로블록 가운데 서브 블록간 최대 복잡도를 가지는 서브블록의 CDF(cumulative distribution function)와 개선된 매칭스캔 방법을 이용하여 효율적으로 계산량을 줄였다. 제안한 알고리즘은 화질의 저하 없이 기존의 PDE 알고리즘에 비해 55% 이상의 계산량을 줄였으며, MPEG-2 및 MPEG-4 AVC를 이용하는 비디오 압축 응용분야에 유용하게 사용될 수 있을 것이다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2008.11a
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• pp.263-266
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• 2008

최근 MPEG에서 HD (High Definition) 해상도 이상의 초고해상도 비디오를 위한 HVC 표준화에 대해 논의가 되고 있다. 본 논문에서는 HVC 표준화를 위해 기본적으로 필요한 H.264를 HD 이상의 초고해상도 부호화 적용시 문제점을 분석하기 위해 SVT 4K UHD테스트 시퀀스와 이를 SVC Downsampling 필터를 이용하여 HD, QHD, QQHD로 변환한 시퀀스들을 이용하여 부호화 실험을 수행 하였고, 실험 결과 분석을 통해 개선 방안에 대해 논하였다.