• Journal of the Institute of Electronics Engineers of Korea CI
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• v.45 no.2
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• pp.26-32
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• 2008

Video compression schemes have been developed and used for many years. Currently, H.264/AVC is the most efficient video coding standard. The H.264/AVC baseline profile adopts CAVLC(Context-Adaptive Variable Length Coding) method as an entropy coding method. CAVLC gives better performance in compression ratios than conventional VLC(Variable Length Coding). However, because CAVLC decoder uses a lot of VLC tables, the CAVLC decoder requires a lot of area in terms of hardware. Conversely, since it must look up the VLC tables, it gives a worse performance in terms of software. In this paper, we propose a new hierarchical grouping method for the VLC tables. We can obtain an index of codes in the reconstructed VLC tables by simple arithmetic operations. In this method, the VLC tables are accessed just once in decoding a symbol. We modeled the proposed algorithm in C language, compiled under ARM ADS1.2 and simulated it with Armulator. Experimental results show that the proposed algorithm reduces execution time by about 80% and 15% compared with the H.264/AVC reference program JM(Joint Model) 10.2 and the arithmetic operation algorithm which is recently proposed, respectively.

• Journal of the Korea Society of Computer and Information
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• v.21 no.5
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• pp.31-40
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• 2016

In this paper, we analyse the characteristics of the edge image and propose a new entropy coding optimized to the compression of the edge image. The pixel values of the edge image have the Gaussian distribution around '0', and most of the pixel values are '0'. By using this analysis, the Zero Block technique is utilized in spatial domain. And the Intra Prediction Mode of the edge image is similar to the mode of the surrounding blocks or likely to be the Planar Mode or the Horizontal Mode. In this paper, we make use of the MPM technique that produces the Intra Prediction Mode with high probability modes. By utilizing the above properties, we design a new entropy coding method that is suitable for edge image and perform the compression. In case the existing compression techniques are applied to edge image, compression ratio is low and the algorithm is complicated as more than necessity and the running time is very long, because those techniques are based on the natural images. However, the compression ratio and the running time of the proposed technique is high and very short, respectively, because the proposed algorithm is optimized to the compression of the edge image. Experimental results indicate that the proposed algorithm provides better visual and PSNR performance up to 11 times than the JPEG.

• Journal of IKEEE
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• v.19 no.2
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• pp.254-259
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• 2015

CABAC is a context-based adaptive binary arithmetic coding method. It increases the encoding efficiency by updating the probability based on the information of the previously coded symbols. Context modeler is a core block of CABAC, which designs a probability model according to the symbol considering statistical correlations. In this paper, an efficient hardware architecture of CABAC context modeler is proposed. The proposed context modeler was designed in Verilog HDL and it was implemented in 0.18 um technology. Its gate count is 29,832 gates including memory. Its operating speed and throughput are 200 MHz and 200 Mbin/s, respectively.

• ETRI Journal
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• v.30 no.1
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• pp.167-169
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• 2008

In this paper, we propose hardware architecture for a high-speed context-adaptive variable length coding (CAVLC) decoder in H.264. In the CAVLC decoder, the codeword length of the current decoding block is used to determine the next input bitstreams (valid bits). Since the computation of valid bits increases the total processing time of CAVLC, we propose two techniques to reduce processing time: one is to reduce the number of decoding steps by introducing a lookup table, and the other is to reduce cycles for calculating the valid bits. The proposed CAVLC decoder can decode $1920{\times}1088$ 30 fps video in real time at a 30.8 MHz clock.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2017.06a
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• pp.254-255
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• 2017

HEVC(High Efficiency Video Coding) 보다 뛰어난 압축 성능을 갖는 차세대 비디오 부호화 표준 기술 탐색을 하고 있는 JVET(Joint Video Exploratory Team)에서는 기술 검증을 위한 참조 SW 코덱인 JEM(Joint Exploration Model)을 공개하고 있다. JEM 의 화면내 예측 부호화에서는 67 가지의 예측모드를 사용하고 6 개의 MPM(Most Probable Mode)을 이용하여 예측모드를 부호화 한다. 본 논문에서는 코딩블록에서의 화면내 예측모드의 선택 확률을 바탕으로 보다 효율적인 예측모드 부호화 기법을 제안한다. 실험결과 JEM 5.0 대비 MPM 을 포함한 예측모드 부호화 정보의 CABAC(Context Adaptive Binary Arithmetic Coding) 엔트로피 부호화를 제외하고, AI(All Intra) 부호화 구조에서 0.23% 정도의 BD-rate 감소를 보임을 확일 할 수 있었다.

• Journal of IKEEE
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• v.18 no.4
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• pp.630-635
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• 2014

In this paper, hardware architecture of BAE (binary arithmetic encoder) was proposed for HEVC (high efficiency video coding) CABAC (context-based adaptive binary arithmetic coding) encoder. It can encode each bin in a single cycle. It consists of controller, regular encoding engine, bypass encoding engine, and termination engine. The proposed BAE was designed in Verilog HDL, and it was implemented in 180 nm technology. Its operating speed, gate count, and power consumption are 180 MHz, 3,690 gates, and 2.88 mW, respectively.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.3
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• pp.119-126
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• 2013

Achieve real-time encryption and video data transcoding, current video encryption methods usually integrate encryption algorithm with video compression course. This paper is devoted to discussing the video encryption technology, by encrypting to avoid unauthorized person getting video data. This paper studied the H.264 entropy coding and proposed of CAVLC video encryption scheme which is combined with the process of entropy coding of H.264 CAVLC encryption scheme. Three encryption levels are proposed. In addition, a scrambling method is also proposed which makes the encrypted frames more robust in anti crack. This method showed more robust video data encryption function and compressive rate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.3A
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• pp.157-162
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• 2012

In this paper, we propose a new intra mode coding method using the candidate mode table. In the conventional HEVC, if the predicted most probable mode (MPM) is not same with the current prediction mode, the current prediction mode is encoded using the fixed length code (FLC). However, since a large number of modes are used in HEVC, the codeword length of FLC gets longer. In this paper, we generate the candidate mode table from neighboring blocks and encode the obtained intra mode index using Golomb-Rice code instead of FLC, when the predicted MPM is not identical to the current mode. From the experiment, we verified that the proposed method reduces the BD-rate by 0.5% on average, compared to the HEVC intra mode coding method.

• 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.