Abstract
Transmitting video data over wireless networks can be very unreliable due to packet loss, leading to serious video quality degradation which is annoying to human perception. The error due to lost packets not only affects the quality of current frame, but also propagates to subsequent frames due to the motion compensation technique used in standard video codecs. Adding error-resilience to video bitstream for robust video delivery to users thus becomes a very important issue. In this work, we propose a two-pass transcoding scheme for enhance the capability of error-resilience in the media gateway of a three-tier streaming system. The transcoder can adapt intra-refresh rate according to a channel's packet loss rate, hence protect the most important MBs subjected to packet loss. Experimental results show that the proposed method can effectively mitigate the error propagation due to packet loss and improve the video quality significantly.