Video quality optimization algorithm for video-telephony over IP networks

Received video quality is dependent on the available link rate and the packet loss rate, which are inter-related in a busy network link. Even low packet loss ratios (PLRs) can significantly reduce the video quality. In this paper, a packet level parity 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 and the introduction of an additional delay at the decoder-side, but this delay can be limited by limiting the length of a FEC block. 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 at the cost of an acceptable delay.