• Journal of the Korea Society of Computer and Information
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• v.16 no.7
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• pp.59-65
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• 2011

Korea DMB Service is popularized, and is used by many users. But latest display devices compared to the DMB content resolution support higher resolution and a variety of video resampling technologies has been used. Generally, subjective video quality is determined by object recognition rate in video, and increased as the edge space between objects are more clear. An edge is the boundary between an object and the background, and indicates the boundary between overlapping objects. the predicted direction in intra prediction used in H.264/AVC has the similarity up to 80% for the edge information. In the study, we propose an effective up-sampling mothed using the edge information that is extracted for the relationship between the intra prediction data and the DCT coefficient data of H.264 video encoding.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.4
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• pp.280-283
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• 2009

To improve coding performance of scalable video coding which is an emerging video coding standard as an extension of H.264/AVC, SVC uses not only intra prediction and inter prediction but inter-layer prediction. This causes a problem that computational complexity is increased. In this paper, we propose an efficient intra prediction mode decision method in spatial enhancement layer to reduce the computational complexity. The proposed method selects Inra_BL mode using RD cost of Intra_BL in advance. After that, intra mode is decided by only comparing DC modes. Experimental results show that the proposed method reduces 59% of the computation complexity of intra prediction coding, while the degradation in video quality is negligible.

• ETRI Journal
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• v.33 no.2
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• pp.145-154
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• 2011

We present a novel video codec for supporting entertainment-quality video. It has new coding tools such as an intra prediction with offset, integer sine transform, and enhanced block-based adaptive loop filter. These tools are used adaptively in the processing of intra prediction, transform, and loop filtering. In our experiments, the proposed codec achieved an average reduction of 13.35% in BD-rate relative to H.264/AVC for 720p sequences.

• ETRI Journal
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• v.34 no.5
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• pp.753-758
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• 2012

As the next-generation video coding standard, High Efficiency Video Coding (HEVC) has adopted advanced coding tools despite the increase in computational complexity. In this paper, we propose a selective bi-prediction method to reduce the encoding complexity of HEVC. The proposed method evaluates the statistical property of the sum of absolute differences in the motion estimation process and determines whether bi-prediction is performed. A performance comparison of the complexity reduction is provided to show the effectiveness of the proposed method compared to the HEVC test model version 4.0. On average, 50% of the bi-prediction time can be reduced by the proposed method, while maintaining a negligible bit increment and a minimal loss of image quality.

• Journal of Korea Multimedia Society
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• v.15 no.9
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• pp.1093-1101
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• 2012

Multi-view video is obtained by capturing one three-dimensional scene with many cameras at different positions. Multi-view video coding exploits inter-view correlations among pictures of neighboring views and temporal correlations among pictures of the same view. Multi-view video coding which uses many cameras requires a method to reduce the computational complexity. In this paper, we proposed an efficient prediction structure to improve performance of multi-view video coding. The proposed prediction structure exploits an average distance between the current picture and its reference pictures. The proposed prediction structure divides every GOP into several small groups to decide the maximum index of hierarchical B layer and the number of pictures of each B layer. Experimental results show that the proposed prediction structure shows good performance in image quality and bit-rates. When compared to the performance of hierarchical B pictures of Fraunhofer-HHI, the proposed prediction structure achieved 0.07~0.13 (dB) of PSNR gain and was down by 6.5(Kbps) in bitrate.

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.6
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• pp.422-433
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• 2015

In this paper, we demonstrate inter-layer prediction tools for scalable video coders. The proposed scalable coder is designed to support not only spatial, quality and temporal scalabilities, but also view scalability. In addition, we propose quad-tree inter-layer prediction tools to improve coding efficiency at enhancement layers. The proposed inter-layer prediction tools generate texture prediction signal with exploiting texture, syntaxes, and residual information from a reference layer. Furthermore, the tools can be used with inter and intra prediction blocks within a large coding unit. The proposed framework guarantees the rate distortion performance for a base layer because it does not have any compulsion such as constraint intra prediction. According to experiments, the framework supports the spatial scalable functionality with about 18.6%, 18.5% and 25.2% overhead bits against to the single layer coding. The proposed inter-layer prediction tool in multi-loop decoding design framework enables to achieve coding gains of 14.0%, 5.1%, and 12.1% in BD-Bitrate at the enhancement layer, compared to a single layer HEVC for all-intra, low-delay, and random access cases, respectively. For the single-loop decoding design, the proposed quad-tree inter-layer prediction can achieve 14.0%, 3.7%, and 9.8% bit saving.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.2
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• pp.95-105
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• 2005

This paper proposes a new dynamic video adaptation scheme that could generate an adapted video stream customized to the requesting mobile device and current network status without repeated decode-encode cycles. In the proposed adaptation scheme, the characteristics of the video codec such as MPEG-1/-2/-4 are analyzed in advance focused on the relationships between the size and Quality of the encoded video stream, and they are stored in the proxy as a codec-dependent characteristic table. When a mobile device requests a video stream, it is dynamically decoded-encoded in the proxy with the highest quality to extract the contents-dependent attributes of the requested video stream. By comparing these attributes with codec-dependent characteristic table, the size and Quality of the requested video stream when being adapted to the target mobile device could be predicted. With this prediction, a version of adapted video stream, that meets the size constraints of mobile device while keeping the quality of encoded video stream as high as possible, could be selected without repeated decode-encode cycles. Experimental results show that the errors in our proposed scheme are less than 5% and produce an appropriate adapted video stream very quickly. It could be used t(1 build a proxy server for mobile devices that could quickly transcode the video streams widely spread in Internet which are encoded with various video codecs.

• Journal of information and communication convergence engineering
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• v.7 no.4
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• pp.501-506
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• 2009

In the H.264/ AVC video coding standard, the intra-prediction coding with various block sizes offers a considerably high improvement in coding efficiency compared to previous standards. In order to achieve this, H.264/AVC uses the Rate-distortion optimization (RDO) technique to select the best intraprediction mode for a macroblock, and it brings about the drastic increase of the computation complexity of H.264 encoder. To reduce the computation complexity and stabilize the coding performance on visual quality, this paper proposed a fast intra-prediction mode decision algorithm using non-parametric thresholds and simplified directional masks. The use of nonparametric thresholds makes the intra-coding performance not be dependent on types of video sequences and simplified directional masks reduces the compuation loads needed by the calculation of local edge information. Experiment results show that the proposed algorithm is able to reduce more than 55% of the whole encoding time with a negligible loss in PSNR and bitrates and provides the stable performance regardless types of video sequences.

• Journal of Broadcast Engineering
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• v.12 no.5
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• pp.491-502
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• 2007

In this parer, we propose an efficient intra prediction mode decision scheme in Scalable Video Coding(SVC) which is an emerging video coding standard as an extension of H.264/MPEG-4 AVC(Advanced Video Coding). The proposed method in base on the characteristic of macroblock smoothness follows the statistical analysis of intra prediction mode in an enhancement layer and it decides a candidate intra prediction mode. We also propose an early termination scheme for Intra_BL mode decision where the RD cost value of Intra_BL is utilized. Simulation results show that the proposed method reduces 54.67% of the computation complexity of intra prediction coding, while the degradation in video quality is negligible; for low QP values, the average PSNR loss is very negligible, equivalently the bit rate increases by 0.011%. For high QP values, the average PSNR loss is less than 0.01dB, which equals to 0.249% increase in bitrate.

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.1
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• pp.16-21
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• 2015

Most video services are transmitted in wireless networks. In a network environment, a packet of video is likely to be lost during transmission. For this reason, numerous error concealment (EC) algorithms have been proposed to combat channel errors. On the other hand, most existing algorithms cannot conceal the whole missing frame effectively. To resolve this problem, this paper proposes a new Adaptive Prediction Unit-based Motion Vector Extrapolation (APMVE) algorithm to restore the entire missing frame encoded by High Efficiency Video Coding (HEVC). In each missing HEVC frame, it uses the prediction unit (PU) information of the previous frame to adaptively decide the size of a basic unit for error concealment and to provide a more accurate estimation for the motion vector in that basic unit than can be achieved by any other conventional method. The simulation results showed that it is highly effective and significantly outperforms other existing frame recovery methods in terms of both objective and subjective quality.