• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.5
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• pp.72-78
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• 2008

Although the H.264 video coding scheme is popular, it is not efficient for high-definition (HD) video coding because the size of its macroblock is relatively small for the HD video resolution. In this paper, we propose a new intra coding scheme based on the enlarged macroblock size. For the luminance component, intra $4{\times}4$ prediction and intra $16{\times}16$ prediction in H.264 are scaled into intra $8{\times}8$ prediction and intra $32{\times}32$ prediction, respectively. For the chrominance components, intra $8{\times}8$ prediction is extended to intra $16{\times}16$ prediction. Along with the $8{\times}8$ basic coding block size, an $8{\times}8$ integer discrete cosine transform (DCT) is used. Experimental results show that the proposed algorithm improves coding efficiency of the intra coding for HD video: PSNR gain by 0.23dB and bit-rate reduction by 5.32% on average.

• ETRI Journal
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• v.28 no.6
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• pp.721-731
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• 2006

A fast intra skip detection algorithm based on the ratedistortion (RD) cost for an inter frame (P-slices) is proposed for H.264/AVC video encoding. In the H.264/AVC coding standard, a robust rate-distortion optimization technique is used to select the best coding mode and reference frame for each macroblock (MB). There are three types of intra predictions according to profiles. These are $16{\times}16$ and $4{\times}4$ intra predictions for luminance and an $8{\times}8$ intra prediction for chroma. For the high profile, an $8{\times}8$ intra prediction has been added for luminance. The $4{\times}4$ prediction mode has 9 prediction directions with 4 directions for $16{\times}16$ and $8{\times}8$ luma, and $8{\times}8$ chrominance. In addition to the inter mode search procedure, an intra mode search causes a significant increase in the complexity and computational load for an inter frame. To reduce the computational load of the intra mode search at the inter frame, the RD costs of the neighborhood MBs for the current MB are used and we propose an adaptive thresholding scheme for the intra skip extraction. We verified the performance of the proposed scheme through comparative analysis of experimental results using joint model reference software. The overall encoding time was reduced up to 32% for the IPPP sequence type and 35% for the IBBPBBP sequence type.

• Journal of Broadcast Engineering
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• v.14 no.5
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• pp.589-600
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• 2009

This paper is ready to change a trend of a ultra high definition (UHD) video image, and it will contribute to improve the performance of the latest H.264 through the Uni-directional $8{\times}8$ intra-prediction idea which is based on developing a intra prediction compression. The Uni-directional $8{\times}8$ intra prediction is focused on a $8{\times}8$ block intra prediction using $4{\times}4$ block based prediction which is using the same direction of intra prediction. This paper describes that the uni-directional $8{\times}8$ intra-prediction gets a improvement around 7.3% BDBR only in the $8{\times}8$ block size, and it gets a improvement around 1.3% BDBR in the H.264 applied to the multi block size structures. In the case of a larger image size, it can be changed to a good algorithm. Because the video codec which is optimized for UHD resolution can be used a different block size which is bigger than before(currently a minimum of $4{\times}4$ blocks of units).

• ETRI Journal
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• v.31 no.5
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• pp.610-612
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• 2009

We present intra-mixture prediction (IMP) mode for intra prediction and an enhanced estimation method for most probable mode (MPM). IMP mode supports more flexibility in intra prediction by mixing $4{\times}4$ blocks and $8{\times}8$ blocks in one macroblock, while the enhanced MPM estimation extends the number of referenced neighboring blocks and efficiently uses their prediction modes depending on their positions. Simulation results show that the combination of both proposed methods provides a bit reduction in the Bj${\phi}$ntegaard delta bitrate by an average of 2.56% compared to H.264/AVC.

• Journal of Broadcast Engineering
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• v.15 no.6
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• pp.815-829
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• 2010

In this paper, we propose a new $4{\times}4$ intra coding method by unidirectional prediction for improvement of intra-frame coding efficiency of H.264/AVC. There are $4{\times}4$, $8{\times}8$, and $16{\times}16$ intra prediction modes in the current H.264/AVC. For the $4{\times}4$ intra prediction, coding efficiency is achieved by accurate prediction with small block size in relatively complicated regions, and the $16{\times}16$ intra prediction method can predict more accurately compared to $4{\times}4$ intra prediction with only one directional information in relatively homogeneous regions. We propose a unidirectional $4{\times}4$ intra prediction method adopting a small-size prediction and one directional prediction approaches. In order to improve coding efficiency, the proposed method is conducted by $4{\times}4$ block and their prediction directions are all the same, resulting that we need to send only one directional information for each macroblock. For intra-frame coding setting, we achieve 10.47% and 1.57% coding efficiency in BD-bitrate for only $16{\times}16$ intra mode and $4{\times}4$, $16{\times}16$ intra mode, respectively.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.5
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• pp.1-9
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• 2010

In this paper, the novel architecture of Intra-prediction & DCTQ hardware, which can process for the Full HD image($1980{\times}1088$@30fps) in realtime, is proposed. The cycle optimization method for the overall cycle of prediction, transform, scaling, descaling, and reconstruction is proposed. To reduce the cycle in the $4{\times}4$ prediction, the quantization process is performed during the prediction cycle and pre-selection of 2 modes among the 9 modes is performed to reduce the hardware area. To reduce the hardware of $16{\times}16$ and $8{\times}8$ prediction, the sharing logic between 2 prediction is utilized. The proposed architecture can process the 30frame/sec of full HD image in 108 MHz clock and operate 425 cycle for one macroblock.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.9
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• pp.103-109
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• 2008

This paper presents the architecture and design of intra prediction circuit for H.264 decoder. There are a total of 17 operational modes in the intra prediction of H.264- nine modes for a luma $4\times4$ block, four modes for a luma $16\times16$ block and four modes for a chroma $8\times8$ block. We extracted common operations included in all prediction modes and defined the common operations unit to perform those operations. The proposed circuit architecture sharing this unit in all prediction modes is systematic from the design point of view and efficient in terms of circuit size.

• Journal of Korea Multimedia Society
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• v.11 no.7
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• pp.956-965
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• 2008

H.264/AVC is the newest video coding standard of ITU-T VCEG and the ISO/IEC MPEG, offering a significant performance improvement over previous video coding standards. However, the computational complexity of H.264/AVC is drastically increased because of new technologies such as intra prediction, variable block size, quarter-pels motion estimation/compensation, etc. In this paper, we propose a fast intra prediction scheme which has two step processing. The first step is a fast block size decision which can be calculated only in one block without considering all cases of $4{\times}4$ block and $16{\times}16$ block. The complexity of the intra prediction can be reduced by using boundary difference values of macroblock. After selecting the block size, we can make mode decision using the neighbouring reference pixels and representative pixels of the block in the second step. The experimental results show that the proposed algorithm saved on the average 41.5% encoding time without any significant PSNR losses.

• Proceedings of the Korean Information Science Society Conference
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• 2004.10c
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• pp.460-462
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• 2004

최신의 동영상 압축 표준인 H.264[1]는 기존의 동영상 압축 표준에 비해 압축 성능이 매우 높으며 4$\times$4 DCT(Discrete Cosine Transform)를 수행하는 특징이 있다. H.264 표준에서는 압축 효율을 높이기 위해 Intra 프레임 내의 이웃한 픽셀칸의 연관성을 이용한 프레임 내 창조(Intra Prediction)를 수행한다. 그러므로 기존의 동영상 압축 데이터를 H.264로 변환하기 위해서는 intra 프레임의 프레임 내 창조와 8$\times$8 DCT 블록의 4$\times$4 정수형 DCT 블록으로의 변환을 필수적으로 수행해야 한다. 또한, Intra 프레임은 GOP 내의 다른 프레임의 창조 대상이 되므로 변환 시 화질의 최적화가 필수적이다[2]. 본 논문에서는 Intra 프레임의 변환 시 화질의 최적화를 위해 DCT 도메인 상에서 프레임 내 창조를 수행하는 기법을 제안한다. 제안된 기법은 추가적인 계산없이 DCT 변환으로 인한 오류를 줄여 변환된 intra 프레임의 화질을 개선할 수 있다.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.993-994
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• 2008

There are nine modes of the intra prediction for $4{\times}4$ luma blocks in H.264/AVC, each of which is identified by the prediction direction and reference pixels. Especially, mode 8 is modified to enhance coding efficiency, considering that the mode does not use left-bottom pixels although they are available. That is, we propose a modified intra prediction method of mode 8 which uses left-bottom pixels if available.