• Journal of Broadcast Engineering
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• v.27 no.2
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• pp.216-227
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• 2022

The MPEG-I (Immersive) group is working on a standardization project for immersive video that provides 6 degrees of freedom (6DoF). The MPEG Immersion Video (MIV) standard technology is intended to provide limited 6DoF based on depth map-based image rendering (DIBR) technique. Many efficient coding methods have been suggested for MIV, but efficient transmission strategies have received little attention in MPEG-I. This paper proposes group-based adaptive rendering method for immersive video streaming. Each group can be transmitted independently using group-based encoding, enabling adaptive transmission depending on the user's viewport. In the rendering process, the proposed method derives weights of group for view synthesis and allocate high quality bitstream according to a given viewport. The proposed method is implemented through the Test Model for Immersive Video (TMIV) test model. The proposed method demonstrates 17.0% Bjontegaard-delta rate (BD-rate) savings on the peak signalto-noise ratio (PSNR) and 14.6% on the Immersive Video PSNR(IV-PSNR) in terms of various end-to-end evaluation metrics in the experiment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2A
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• pp.144-153
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• 2006

In this paper, we propose an efficient video data transmission protocol using the cross-layer approach in ad hoc networks. Due to node movement, the MANET is frequently changing path and each path has different transmission rate so that it has low performance when transmitters select a constant transmission late at the encoding time. Because MANET is running limited energy, efficient energy management is important because it increases network life time and network throughput. Therefore we need an effective video transmission method that considers physical layer channelstatistics, node's energy status, and network topology changes at the same time unlike the OSI recommendation protocol in that each layer isindependent and hard to transmit adaptively video data according to the network conditions. Therefore, in this paper we propose a cross-layer effective video transmission protocol and mechanism that can select an optimal path using multilayer information such as node's residual energy, channel condition and hop counts and can determine the adequate coding rate adaptively.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.7
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• pp.1618-1626
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• 2013

Virtualization service processes all operation including the data creation, storing, and disposal in a server and transmits processed data as the streaming media form. Therefore, client can use the same environment as the traditional desktop environment without considering the type of device. Virtualization service should consider not only the video quality but also the delay bounds and continuity of video playback for improving the user perceived Quality of Service(QoS) of streaming service. In this paper, we propose a network-adaptive transmission architecture that focuses on guaranteeing QoS requirements for virtualization service. In order to provide those, the proposed architecture have the transmission rate adaptation function based on available bandwidth and the content bit-rate control function based on sender buffer state. Through each function, proposed architecture guarantee the delay bounds and continuity of virtualization contents playback. The simulation results show that proposed network-adaptive transmission architecture provides a improve performance of throughput and transmission delay.

• Proceedings of the Korean Information Science Society Conference
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• 1999.10c
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• pp.635-637
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• 1999

기존의 인터넷 기반 데이터 서비스는 'Best-effort' 정책으로 멀티미디어 서비스를 위한 트래픽 제어(traffic control) 기능을 제공하지 못한다. 그러므로 실시간 데이터 전송을 기반으로 제공되는 VOD(Video-on-Demand) 서비스는 사용자가 원하는 QoS(Quality of Service)를 제공할 수 없다. 따라서 인터넷 상에서 트래픽 제어 기능을 갖춘 중개자를 두어 VOD 서비스를 제공하는 방법에 대해 제안한다. 중개자의 주요 기능은 비디오 서버와 클라이언트 사이에 비디오 데이터의 버퍼링 기능을 이용하여 실시간 트래픽 제어를 수행한다. 이런 기능을 가진 중개자를 에이전트라 부르고, 에이전트에 대한 설계 및 구현에 대해 기술한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.3C
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• pp.408-418
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• 2004

In this paper, we propose a novel scalable video coding algorithm based on adaptively weighted multiple reference frame method. To improve the coding efficiency in the enhancement layer, the enhancement frame is predicted by the sum of adaptively weighted double motion compensated frames in the enhancement layer and the current frame in the base layer, according to the input video characteristics. By employing adaptive reference selection scheme at the decoder, the proposed method reduce the drift problem significantly. From the experimental results, the proposed algorithm shows more than 1.0 ㏈ PSNR improvement, compared with the conventional scalable H.263+ for various packet loss rate channel conditions.

• Journal of Broadcast Engineering
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• v.13 no.1
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• pp.119-127
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• 2008

Transmission of video over Internet or wireless network requires coded stream capable of adapting to dynamic network conditions instantly. To meet this requirement, various scalable video coding schemes have been developed, among which the Scalable Video Coding (SVC) extension of the H.264/AVC is the most recent one. In comparison with the scalable profiles of previous video coding standards, the SVC achieves significant improvement on coding efficiency performance. For adapting to dynamic network bandwidth, the SVC employs inter-layer switching between different temporal, spatial or/and fidelity layers, which is currently supported with instantaneous decoding refresh (IDR) access unit. However, for real-time adaptability, the SVC has to frequently employ the IDR picture, which dramatically decreases the coding efficiency. Therefore, an extension of SP picture from the AVC to the SVC for an efficient inter-layer switching is investigated and presented in this paper. Simulations regarding the adaptability to dynamic network bandwidth are implemented. Results of experiment show that the SP picture added SVC provides an average 1.2 dB PSNR enhancement over the current SVC while providing similar adaptive functionality.

• Journal of Advanced Navigation Technology
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• v.13 no.4
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• pp.523-531
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• 2009

In this study, we propose a joint source/channel rate control algorithm for video encoder targeting packet erasure channel. Based on the buffer constraints of video communication systems, encoding rate constraint is presented. After defining source distortion models for coded and skipped video frames and a channel distortion model for packet errors and their propagation, an average distortion model of received video is proposed for a given encoding window. Finally, we define an optimization problem to minimize the average distortion for given channel rates and packet loss rates by controlling spatio-temporal parameters of source video and FEC block sizes. Then, we propose a window-based algorithm to solve the problem in real-time.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.5
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• pp.691-708
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• 2010

An important issue of supporting multi-users with diverse quality-of-service (QoS) requirements over wireless networks is how to optimize the systematic scheduling by intelligently utilizing the available network resource while, at the same time, to meet each communication service QoS requirement. In this work, we study the problem of a variety of communication services over multi-media heterogeneous cognitive OFDM system. We first divide the communication services into two parts. Multimedia applications such as broadband voice transmission and real-time video streaming are very delay-sensitive (DS) and need guaranteed throughput. On the other side, services like file transmission and email service are relatively delay tolerant (DT) so varying-rate transmission is acceptable. Then, we formulate the scheduling as a convex optimization problem, and propose low complexity distributed solutions by jointly considering channel assignment, bit allocation, and power allocation. Unlike prior works that do not care computational complexity. Furthermore, we propose the FAASA (Fairness Assured Adaptive Sub-carrier Allocation) algorithm for both DS and DT users, which is a dynamic sub-carrier allocation algorithm in order to maximize throughput while taking into account fairness. We provide extensive simulation results which demonstrate the effectiveness of our proposed schemes.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.1_2
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• pp.137-146
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• 2006

Traditional live video streaming systems support the limited field of view (FOV) of image to the remote users. A server system based on the pan/tilt camera provides a user with wide view by changing the view direction of the camera mechanically. But, when many clients try to access to the server, this system can not offer their own view to every user simultaneously, and moreover it has the delay by camera motion. In order to offer wide views to several users, we propose new streaming system using the panorama image that has wide view. Our system is a kind of implementation of software pan/tilt camera. The server acquires panorama video and sends a part of the video to clients. Then, each client can control their own view. We need the effective way to reduce the average transmission data size and server burden to the compression because generally the full size of panorama video is too big to be served by the real-time streaming. To solve this problem, we propose an strip-based video compression and adaptive transmission of the compressed multiple strip videos. Experimental results show that our system can be adapted quickly to the change of view and the number of clients. Furthermore, proposed method effectively reduce the transmission data.

• 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.