Publications (3)0 Total impact
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ABSTRACT: With EvalVid we present a complete framework and tool-set for evaluation of the quality of video transmitted over a real or simulated communication network. Besides measuring QoS parameters of the underlying network, like loss rates, delays, and jitter, we support also a subjective video quality evaluation of the received video based on the frame-by-frame PSNR calculation. The tool-set has a modular construction, making it possible to exchange both the network and the codec. We present here its application for MPEG-4 as example. EvalVid is targeted for researchers who want to evaluate their network designs or setups in terms of user perceived video quality. The tool-set is publicly available [11].
03/2004;
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ABSTRACT: Wireless OFDM systems have attractive means for adapting wireless transmission to a given situation: one possibility is to assign a varying number of subcarriers to wireless terminals for downlink communication. Deciding how many and which subcarriers to assign to a given terminal is a difficult problem. This paper concentrates on deciding how many: we use the relative length of a terminal's queue in an access point to determine this number. Applying this scheme to the transmission of homogeneous MPEG-4 videos, we obtain a significant capacity increase compared to nonadaptive subcarrier allocation schemes.
03/2004;
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ABSTRACT: Delivering video streams to terminals via a wireless last hop is a challenging task due to the varying nature of the wireless link. While a common approach suggests to exploit the variations of the wireless channel, an alternative is to exploit characteristics of the video stream to improve the transmission. In this paper we show how semantic stream variations of MPEG-4 coded video can be used to increase the number of terminals which can be supported in a wireless cell at a given minimum video quality. As example system we consider the performance of an OFDM system with different video sources. Simulations show that the number of supportable terminals can be increased on average by fifty percent.
06/2003;
