• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.2
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• pp.408-427
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• 2011

Intensive computational complexity is an obstacle of enabling multiview video coding for real-time applications. In this paper, we present a fast macroblock (MB) mode selection algorithm for B frames which are based on the computational complexity analyses between the MB mode selection and reference frame selection. Three strategies are proposed to reduce the coding complexity jointly. First, the temporal correlation of MB modes between current MB and its temporal corresponding MBs is utilized to reduce computational complexity in determining the optimal MB mode. Secondly, Lagrangian cost of SKIP mode is compared with that of Inter $16{\times}16$ modes to early terminate the mode selection process. Thirdly, reference frame correlation among different Inter modes is exploited to reduce the number of reference frames. Experimental results show that the proposed algorithm can promote the encoding speed by 3.71~7.22 times with 0.08dB PSNR degradation and 2.03% bitrate increase on average compared with the joint multiview video model.

• Proceedings of the Korea Information Processing Society Conference
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• 2007.05a
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• pp.297-300
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• 2007

Due to its impressive compression performance, the H.264 video coder is highlighted in the video communications industry, such as DMB (Digital Multimedia Broadcasting), PMP (Portable Multimedia Player), etc. The main bottleneck to use the H.264 coder lays in the computational complexity, i.e. five times more complex than the market leading MPEG-4 Simple Profile codec. In this paper, we propose the hierarchical mode decision method for intraframe coding for the reduction of the computation complexity of the encoder. By determining the mode group early, the propose algorithm can skip the computationally demanding computation in the mode decision. The proposed algorithm is composed of three steps: $16{\times}16$ mode decision, $4{\times}4$ mode-group decisions, and final mode decision among the selected mode group. The simulation results show that the proposed algorithm achieves 20% to 50% reduction in the computational complexity compared with the conventional algorithm.

• Journal of English Language & Literature
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• v.57 no.6
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• pp.911-938
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• 2011

The present study examined the effect of two variables of task complexity, reasoning demand and time pressure, each from the resourcedirecting and resource-dispersing dimension in Robinson's (2001) framework of task classification. Reasoning demand was operationalized as the two types of texts to read and summarize, expository and argumentative. Time pressure was operationalized as the two modes of performance, oral and written. Six university students summarized the two types of text orally and twenty four students from the same school summarized them in the written form. Results from t test and ANCOVA showed that in the oral mode, reasoning demand tends to heighten the complexity of the language used in the summary in competition with accuracy but such an effect disappeared in the written mode. It was interpreted that the degree of time pressure is not the only difference between the oral and written modes but that the two modes may be fundamentally different cognitive tasks, and that Robinson's (2001) and Skehan's (1998) models were differentially supported by the oral mode of tasks but not by the written mode of the tasks.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.20-22
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• 2007

The H.264/AVC standard developed by the joint Video Team (JVT) provides better coding efficiency than previous standards. The new emerging H.264/AVC employs variable block size motion estimation using multiple reference frame with 1/4-pel MV(Motion Vector) accuracy. These techniques are a important feature to accomplish higher coding efficiency. However, these techniques are increased overall computational complexity. To overcome this problem, this paper proposes advanced fast mode decision suited for variable block size by classifying inter mode based on Rate Distortion Optimization(RDO) technique. Proposed algorithm is going to use to implement H/W structure for fast mode decision. The experimental results shows that the proposed algorithm provides significant reduction computational complexity without any noticeable coding loss and additional computation. Entire computational complexity is decreased about 30%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.10C
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• pp.778-786
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• 2008

The H.264/AVC video coding standard shows superior coding efficiency by adopting many new techniques. However, the encoding complexity increases greatly to achieve higher coding efficiency. Especially, the rate distortion optimization technique, which is used to decide the intra-prediction mode, increases the encoding complexity. In this paper, we propose an efficient intra-prediction mode decision method. By using the variance of pixel values and the edge direction, the computational complexity of the intra-prediction mode decision is greatly reduced.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.3
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• pp.1195-1211
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• 2016

The emerging video coding standard High Efficiency Video Coding (HEVC) has shown almost 40% bit-rate reduction over the state-of-the-art Advanced Video Coding (AVC) standard but at about 40% computational complexity overhead. The main reason for HEVC computational complexity is the inter prediction that accounts for 60%-70% of the whole encoding time. In this paper, we propose several fast coding unit (CU) encoding schemes based on the Merge mode and motion estimation information to reduce the computational complexity caused by the HEVC inter prediction. Firstly, an early Merge mode decision method based on motion estimation (EMD) is proposed for each CU size. Then, a Merge mode based early termination method (MET) is developed to determine the CU size at an early stage. To provide a better balance between computational complexity and coding efficiency, several fast CU encoding schemes are surveyed according to the rate-distortion-complexity characteristics of EMD and MET methods as a function of CU sizes. These fast CU encoding schemes can be seamlessly incorporated in the existing control structures of the HEVC encoder without limiting its potential parallelization and hardware acceleration. Experimental results demonstrate that the proposed schemes achieve 19%-46% computational complexity reduction over the HEVC test model reference software, HM 16.4, at a cost of 0.2%-2.4% bit-rate increases under the random access coding configuration. The respective values under the low-delay B coding configuration are 17%-43% and 0.1%-1.2%.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.1C
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• pp.61-72
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• 2005

For the improvement of coding efficiency, the H.264 standard uses new coding tools such as VBS, 1/4-pel accurate ME, multiple references, intra prediction, loop filter, etc. Using these coding tools, H.264 has achieved significant improvements from rate-distortion point of view compared to existing standards. However, the encoder complexity is greatly increased due to these coding tools. We focus on the complexity reduction method of MB mode selection. Among all modes which can be selected, $8{\times}8$ and intra $4{\times}4$ mode have higher complexity than the others. So we propose the methods for reduction of the $8{\times}8$ and intra $4{\times}4$ mode complexity by using information of other modes with relatively low complexity. Simulation results show that the proposed methods save up to $54.6{\%}$ of total encoding time while keeping the average decrease about 0.012dB in PSNR.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2016.06a
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• pp.264-266
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• 2016

During the $2^{nd}$ JVET (Joint Group on Future Video Coding Technology Exploration) meeting, up to 22 coding tools focusing on Future Video Coding (FVC) were proposed. Despite that the application of proposed coding tools has a considerable performance enhancement, however, the encoding time of Joint Exploration Model (JEM) software is over 20 times for All Intra coding mode, 6 times for Random Access coding mode, of HEVC reference model (HM), and decoding time is 1.6 times for All Intra coding mode, 7.9 times for Random Access coding mode, of HM. This paper focuses on analyzing the complexity of the JEM software compared with HM.

• ETRI Journal
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• v.36 no.4
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• pp.528-536
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• 2014

High Efficiency Video Coding (HEVC) is the most recent video coding standard to achieve a higher coding performance than the previous H.264/AVC. In order to accomplish this improved coding performance, HEVC adopted several advanced coding tools; however, these cause heavy computational complexity. Similar to previous video coding standards, motion estimation (ME) of HEVC requires the most computational complexity; this is because ME is conducted for three inter prediction modes - namely, uniprediction in list 0, uniprediction in list 1, and biprediction. In this paper, we propose an efficient inter prediction mode (EIPM) decision method to reduce the complexity of ME. The proposed EIPM method computes the priority of all inter prediction modes and performs ME only on a selected inter prediction mode. Experimental results show that the proposed method reduces computational complexity arising from ME by up to 51.76% and achieves near similar coding performance compared to HEVC test model version 10.1.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.265-266
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• 2007

New coding tools require the increase of the encoder complexity in H.264. In this paper we propose a fast mode decision method to reduce the computational complexity of mode decision. The simulation results shows that the proposed methods could reduce the coding time of overall sequences by 30% on average without any noticeable degradation of the coding efficiency.