• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.3C
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• pp.249-255
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• 2007

In general, a large amount of the memory accesses are required for the CAVLC decoding in H.264/AVC. It is a serious problem for the applications such as a DMB and videophone services because the considerable power is consumed for accessing the memory. In order to solve this problem, we propose an efficient decoding method for the coeff-token which is one of the syntax elements of CAVLC. In this paper, the variable length code table is re-designed with the new codewords which are defined by investigating the architecture of the conventional codeword for the coeff_token element. A new coeff_token decoding method is developed based on the suggested table. The simulation results show that the proposed algorithm achieves an approximately 85% memory access saving without video-quality degradation, compared to the conventional CAVLC decoding.

• Proceedings of the Korean Information Science Society Conference
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• 2008.06b
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• pp.464-468
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• 2008

본 논문은, H,264/AVC 비디오 코덱의 저전력용 CAVLC 디코더를 위한 coeff_token 회로의 면적을 최적화 한 설계를 제시한다. CAVLC 디코더의 전력 소비를 줄이기 위해서 coeff_token 회로에서의 메모리 참조 빈도수를 줄이는 여러 가지 방법이 제안되어 왔다. 본 논문에서는 기존의 저전력용으로 개발된 coeff_token 회로 중 가장 전력 소비가 낮은 방식의 메모리 구조와 수식 계산 회로를 변형시켜서 전력 소비를 같은 수준으로 유지하면서도 면적을 더욱 줄이는 방법을 제안한다. 본 연구결과를 삼성 0.18 um 공정을 대상으로 합성한 결과 기존 방식에 비해서 1.1% 면적이 줄어드는 성과를 거두었다.

• IEMEK Journal of Embedded Systems and Applications
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• v.5 no.2
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• pp.77-83
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• 2010

In this paper, we propose an efficient memory architecture for coeff_token encoding in H.264/AVC standard. The VLCTs used to encode the coeff_token syntax element are implemented with the memory. In general, the size of memory must be reduced because it affects the cost and operation speed of the system. Based on the analysis for the codewords in VLCTs, new memory architecture is designed in this paper. The proposed memory architecture results in about 24% memory saving, compared to the conventional memory architecture.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.5
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• pp.35-42
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• 2008

In this paper, we propose a fast coeff_token decoding method based on the re-constructed VLCT. Since the conventional decoding method is still based on large memory accesses, it is not suitable for the multimedia services such as PMP, PMB, DVH-H where fast decoding and low power consumption are required. Based on the analysis for the codeword structure, new structure of the codeword and the corresponding memory architecture are developed in this paper. The simulation results show that the proposed algorithm achieves memory access saving from 10% to 57%, compared to the conventional decoding method. This meant that the issues of tow power consumption and high speed decoding can be resolved without video-quality and coding efficiency degradation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.7
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• pp.1485-1490
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• 2005

Variable length code is an integral component of many international standards on image and video compression currently. Context-based Adaptive Variable Length Coding(CAVLC) is adopted by the emerging JVT(also called H.264, and AVC in MPEG-4). In this paper, we design an architecture for CAVLC encoder, including a coeff_token encoder, level encoder, total_zeros encoder and run_before encoder. The designed CAVLC encoder can encode one syntax element in one clock cycle. As a result of implementation by Vertex-1000e of Xilinx, its operation frequency is 68MHz. Therefore, it is very suitable for video applications that require high throughput.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.6
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• pp.1104-1114
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• 2007

Digital video compression technique has played an important role that enables efficient transmission and storage of multimedia data where bandwidth and storage space are limited. The new video coding standard, H.264/AVC, developed by Joint Video Team(JVT) significantly outperforms previous standards in compression performance. Especially, variable length code(VLC) plays a crucial pun in video and image compression applications. H.264/AVC standard adopted Context-based Adaptive Variable Length Coding(CAVLC) as the entropy coding method. CAVLC of H.264/AVC requires a large number of the memory accesses. This is a serious problem for applications such as DMB and video phone service because of the considerable amount of power that is consumed in accessing the memory. In order to overcome this problem in this paper, we propose a variable length technique that implements memory-free coeff_token, level, and run_before decoding based on arithmetic operations and using only 70% of the required memory at total_zero variable length decoding.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.299-302
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• 2005

요즘 시대는 영상 기술과 IT 발전으로 다양한 멀티미디어 서비스를 제공하기 위해 고품질의 비디오와 높은 데이터 압축을 요구하게 되었고, 이를 위해 MPEG-4 AVC/H.264에서는 기존의 MPEG-4에서 채택한 VLC 기술과 유사한 Context-based Adaptive Variable Length Code(CAVLC)기술을 채택하여 이를 가능하게 하였다. 특히 CAVLC 기술은 HDTV처럼 큰 영상 뿐 아니라 카메라폰이나 DMB등과 같은 영상에서 고품질의 영상을 보다 효율적으로 제공 한다. 본 논문은 최근의 이미지와 비디오 압축에 대한 요구에 따라 H.264/AVC와 MPEG4-PART 1-에서 표준으로 채택한 CAVLC의 부호화 과정을 연구하여 Visual C++언어를 이용한 최적화된 시뮬레이션과 CAVLC의 성능평가를 통한 최적화를 실시하였고, 최적화된 예측 정보를 바탕으로 CAVLC를 VHDL언어를 이용하여 하드웨어로 구현하였다.