250,120 research outputs found

    Optimization of high-definition video coding and hybrid fiber-wireless transmission in the 60 GHz band

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    This paper was published in OPTICS EXPRESS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OE.19.00B895. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law[EN] The paper addresses the problem of distribution of highdefinition video over fiber-wireless networks. The physical layer architecture with the low complexity envelope detection solution is investigated. We present both experimental studies and simulation of high quality high-definition compressed video transmission over 60 GHz fiberwireless link. Using advanced video coding we satisfy low complexity and low delay constraints, meanwhile preserving the superb video quality after significantly extended wireless distance. © 2011 Optical Society of America.This work has been partly funded by the European Commission under FP7 ICT-249142 FIVER project and by the by the Spanish Ministry of Science and Innovation under the TEC2009-14250 ULTRADEF project.Lebedev, A.; Pham, T.; Beltrán Ramírez, M.; Yu, X.; Ukhanova, A.; Llorente Sáez, R.; Monroy, I.... (2011). Optimization of high-definition video coding and hybrid fiber-wireless transmission in the 60 GHz band. Optics Express. 19(26):895-904. https://doi.org/10.1364/OE.19.00B895S8959041926Stockhammer, T., Hannuksela, M. M., & Wiegand, T. (2003). H.264/AVC in wireless environments. IEEE Transactions on Circuits and Systems for Video Technology, 13(7), 657-673. doi:10.1109/tcsvt.2003.815167Yong, S. K., & Chong, C.-C. (2006). An Overview of Multigigabit Wireless through Millimeter Wave Technology: Potentials and Technical Challenges. EURASIP Journal on Wireless Communications and Networking, 2007(1). doi:10.1155/2007/7890

    QoE-Based Low-Delay Live Streaming Using Throughput Predictions

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    Recently, HTTP-based adaptive streaming has become the de facto standard for video streaming over the Internet. It allows clients to dynamically adapt media characteristics to network conditions in order to ensure a high quality of experience, that is, minimize playback interruptions, while maximizing video quality at a reasonable level of quality changes. In the case of live streaming, this task becomes particularly challenging due to the latency constraints. The challenge further increases if a client uses a wireless network, where the throughput is subject to considerable fluctuations. Consequently, live streams often exhibit latencies of up to 30 seconds. In the present work, we introduce an adaptation algorithm for HTTP-based live streaming called LOLYPOP (Low-Latency Prediction-Based Adaptation) that is designed to operate with a transport latency of few seconds. To reach this goal, LOLYPOP leverages TCP throughput predictions on multiple time scales, from 1 to 10 seconds, along with an estimate of the prediction error distribution. In addition to satisfying the latency constraint, the algorithm heuristically maximizes the quality of experience by maximizing the average video quality as a function of the number of skipped segments and quality transitions. In order to select an efficient prediction method, we studied the performance of several time series prediction methods in IEEE 802.11 wireless access networks. We evaluated LOLYPOP under a large set of experimental conditions limiting the transport latency to 3 seconds, against a state-of-the-art adaptation algorithm from the literature, called FESTIVE. We observed that the average video quality is by up to a factor of 3 higher than with FESTIVE. We also observed that LOLYPOP is able to reach a broader region in the quality of experience space, and thus it is better adjustable to the user profile or service provider requirements.Comment: Technical Report TKN-16-001, Telecommunication Networks Group, Technische Universitaet Berlin. This TR updated TR TKN-15-00

    Streaming Non-monotone Submodular Maximization: Personalized Video Summarization on the Fly

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    The need for real time analysis of rapidly producing data streams (e.g., video and image streams) motivated the design of streaming algorithms that can efficiently extract and summarize useful information from massive data "on the fly". Such problems can often be reduced to maximizing a submodular set function subject to various constraints. While efficient streaming methods have been recently developed for monotone submodular maximization, in a wide range of applications, such as video summarization, the underlying utility function is non-monotone, and there are often various constraints imposed on the optimization problem to consider privacy or personalization. We develop the first efficient single pass streaming algorithm, Streaming Local Search, that for any streaming monotone submodular maximization algorithm with approximation guarantee α\alpha under a collection of independence systems I{\cal I}, provides a constant 1/(1+2/α+1/α+2d(1+α))1/\big(1+2/\sqrt{\alpha}+1/\alpha +2d(1+\sqrt{\alpha})\big) approximation guarantee for maximizing a non-monotone submodular function under the intersection of I{\cal I} and dd knapsack constraints. Our experiments show that for video summarization, our method runs more than 1700 times faster than previous work, while maintaining practically the same performance
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