Robust video calls for emergency services over IP based networks

Abstract

Network links in emergency or rescue scenarios often operate under difficult circumstances, which makes live video feedback almost unusable. Received video quality is dependent on the available link rate and the packet loss ratio, which are inter-related in a congested network link. Even low packet loss ratios (PLRs) can significantly reduce the video quality. In this paper, a packet level parity Forward Error Correction (FEC) is applied to the video stream in order to reduce the video PLR. A constant gross data rate is assumed, such that adding a FEC leads to a decrease in effective video data rate. The FEC block is truncated at the end of each video frame, such that there are no inter-frame dependencies for FEC correction. An algorithm is proposed to optimize the FEC length, based on the Quality of Experience as modelled by the ITU-T R G.1070 standard. It is shown that the optimization algorithm can significantly increase the video quality, without increasing the gross data rate. The algorithm has been evaluated through simulations, which confirm the very significant increases in subjective video quality. © 2012 ICST Institute for Computer Science, Social Informatics and Telecommunications Engineering.