• Journal of Information Processing Systems
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• v.15 no.3
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• pp.492-499
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• 2019

HEVC is the high efficiency video coding standard, which provides better coding efficiency contrasted with the other video coding standard. But at the same time the computational complexity increases drastically. Thirty-five kinds of intra-prediction modes are defined in HEVC, while 9 kinds of intra prediction modes are defined in H.264/AVC. This paper proposes a fast rough mode decision (RMD) algorithm which adopts the smoothness of the up-reference pixels and the left-reference pixels to decrease the computational complexity. The three step search method is implemented in RMD process. The experimental results compared with HM13.0 indicate that the proposed algorithm can save 39.7% of the encoding time, while Bjontegaard delta bitrate (BDBR) is increased slightly by 1.35% and Bjontegaard delta peak signal-to-noise ratio (BDPSNR) loss is negligible.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.1
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• pp.385-405
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• 2019

High Efficiency Video Coding (HEVC) enables significantly improved compression performance relative to existing standards. However, the advance also requires high computational complexity. To accelerate the intra prediction mode decision, a minimum risk Bayesian classification framework is introduced. The classifier selects a small number of candidate modes to be evaluated by a rate-distortion optimization process using the sum of absolute Hadamard transformed difference (SATD). Moreover, the proposed method provides a loss factor that is a good trade-off model between computational complexity and coding efficiency. Experimental results show that the proposed method achieves a 31.54% average reduction in the encoding run time with a negligible coding loss of 0.93% BD-rate relative to HEVC test model 16.6 for the Intra_Main common test condition.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2018.06a
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• pp.317-319
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• 2018

최근 인터넷을 통한 UHD (Ultra High Definition) 스트리밍 서비스의 수요가 증가했으며 네트워크에 효율적으로 비디오 스트리밍 서비스를 제공하기 위해 HTTP 적응적 스트리밍 (HTTP Adaptive Streaming, HAS) 서비스가 등장하였다. 그러나 HTTP 적응적 스트리밍은 세그먼트의 ON-OFF 패턴으로 인해 다중 클라이언트 환경에서 공정성 (Fairness), 안정성 (Stability), 효율성 (Efficiency)을 저하시키는 문제가 있다. 본 논문에서는 다수의 HAS 클라이언트 환경에서 공정성, 안정성, 효율성을 향상시키기 위한 홈 공유기에서 인코딩 비트율 기반의 대역폭 할당 기법을 제안한다. 제안 기법은 OFF 구간을 줄이기 위해 인코딩 비트율에 맞추어 할당할 대역폭을 결정함으로써 안정적인 스트리밍을 보장한다. 실험을 통해 다중 HAS 클라이언트 환경에서 공정성, 안정성 및 효율성이 향상된 것을 확인하였다.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.8
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• pp.793-797
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• 2008

To achieve flexible visual contents adaptation for multimedia communications, the ISO/IEC MPEG & ITU-T VCEG form the JVT to develop an SVC amendment for the H.264/AVC standard. JVT uses inter-layer prediction that can improve the rate-distortion efficiency of the enhancement layer. But inter-layer prediction causes computational complexity to be increased. In this paper, we propose a fast mode decision for inter frame coding. It makes use of the correlation between optimized prediction mode and its RD cost. Experimental results show that the proposed schemes save up to 38% of encoding time with a negligible coding loss and bit-rate increase.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.12
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• pp.6017-6037
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• 2017

In a multi-resolution image encoding system, the image is encoded into a single file as a layer of bit streams, and then it is transmitted layer by layer progressively to reduce the transmission time across a low bandwidth connection. This encoding scheme is also suitable for multiple decoders, each with different capabilities ranging from a handheld device to a PC. In our previous work, we proposed an edge adaptive hierarchical interpolation algorithm for multi-resolution image coding system. In this paper, we enhanced its compression efficiency by adding three major components. First, its prediction accuracy is improved using context adaptive error modeling as a feedback. Second, the conditional probability of prediction errors is sharpened by removing the sign redundancy among local prediction errors by applying sign flipping. Third, the conditional probability is sharpened further by reducing the number of distinct error symbols using error remapping function. Experimental results on benchmark data sets reveal that the enhanced algorithm achieves a better compression bit rate than our previous algorithm and other algorithms. It is shown that compression bit rate is much better for images that are rich in directional edges and textures. The enhanced algorithm also shows better rate-distortion performance and visual quality at the intermediate stages of progressive image transmission.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.6
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• pp.2144-2159
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• 2015

CISCO VNI predicted an average annual growth rate of 66% for mobile video traffic between 2014 and 2019 and accordingly much academic research related to video streaming has been initiated. In video streaming, Adaptive Bitrate (ABR) is a streaming technique in which a source video is stored on a server at variable encoding rates and each streaming user requests the most appropriate video encoding rate considering their channel capacity. However, these days, ABR related studies are only focusing on real-time rate adaptation omitting energy efficiency though it is one of the most important requirement for mobile devices, which may cause dissatisfaction for streaming users. In this paper, we propose an energy efficient prefetching based dynamic adaptive streaming technique by considering the limited characteristics of the batteries used in mobile devices, in order to reduce the energy waste and provide a similar level of service in terms of the average video rate compared to the latest ABR streaming technique which does not consider the energy consumption. The simulation results is showing that our proposed scheme saves 65~68% of energy at the average global mobile download speed compared to the latest high performance ABR algorithm while providing similar rate adaptation performance.

• Journal of Korea Multimedia Society
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• v.18 no.2
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• pp.149-157
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• 2015

The 3D-AVC standard aims at improving coding efficiency by applying new techniques for utilizing intra, inter and view predictions. 3D video scenes are rendered with existing texture video and additional depth map. The depth map comes at the expense of increased computational complexity of the encoding process. For real-time applications, reducing the complexity of 3D-AVC is very important. In this paper, we present a fast intra mode decision algorithm to reduce the complexity burden in the 3D video system. The proposed algorithm uses similarity between texture video and depth map. The best intra prediction mode of the depth map is similar to that of the corresponding texture video. The early decision algorithm can be made on the intra prediction of depth map coding by using the coded intra mode of texture video. Adaptive threshold for early termination is also proposed. Experimental results show that the proposed algorithm saves the encoding time on average 29.7% without any significant loss in terms of the bit rate or PSNR value.

• Journal of Plant Biotechnology
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• v.38 no.1
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• pp.77-86
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• 2011

Alcohol dehydrogenase (E.C.1.1.1.1) is an enzyme present in higher plants involved in the anaerobic fermentation pathway that catalyzes the reduction of pyruvate to ethanol, resulting in continuous $NAD^+$ regeneration. It also plays an important role in many plant developments including tolerance to anoxia condition. Here, a cDNA clone encoding alcohol dehydrogenase (ADH) was isolated from Chinese cabbage (Brassica rapa) seedlings. The gene named Bradh1 had a total length of 1,326 bp that contains a single open reading frame of 1,140 bp. The predicted protein consists of 379 amino acid residues with a calculated molecular mass of 41.17 kDa. Expression pattern analysis revealed a tissue-specific expressing gene in different tissues and strongly expressed in the shoot, roots and seeds of Chinese cabbage. Agrobacterium transformation of full-length cDNA Bradh1 into rice Gopumbyeo showed high efficiency. Furthermore, induction of ADH in transgenic rice enhanced tolerance to anaerobiosis stresses and elevated mRNA transcripts. The overexpression of Bradh1 in rice increases germination under anaerobiosis stresses, implying the possibility of developing new varieties suited for direct seeding or flood-prone rice field.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.7
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• pp.3286-3300
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• 2016

High Efficiency Video Coding (HEVC) Standard, as the latest coding standard, introduces satisfying compression structures with respect to its predecessor Advanced Video Coding (H.264/AVC). The new coding standard can offer improved encoding performance compared with H.264/AVC. However, it also leads to enormous computational complexity that makes it considerably difficult to be implemented in real time application. In this paper, based on machine learning, a fast partitioning method is proposed, which can search for the best splitting structures for Intra-Prediction. In view of the video texture characteristics, we choose the entropy of Gray-Scale Difference Statistics (GDS) and the minimum of Sum of Absolute Transformed Difference (SATD) as two important features, which can make a balance between the computation complexity and classification performance. According to the selected features, adaptive decision trees can be built for the Coding Units (CU) with different size by offline training. Furthermore, by this way, the partition of CUs can be resolved as a binary classification problem. Experimental results have shown that the proposed algorithm can save over 34% encoding time on average, with a negligible Bjontegaard Delta (BD)-rate increase.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.48 no.1
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• pp.132-140
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• 2011

Ultra-High Definition Television (U-HDTV) is a promising candidate for the next generation television. Since the U-HDTV video signal requires a huge amount of data, parallel implementation of the U-HDTV compression system is highly demanding. In the conventional parallel video codec, a video is divided into sub-sequences and the sub-sequences are independently encoded. In this paper, for efficient parallel processing, we propose a pipelined encoding structure which exploits cross-correlation among the sub-sequences. The experimental results demonstrate that the proposed technique improves the coding efficiency and provides the sub-sequences of the balanced visual quality.