Network-aware source-adaptive video coding for wireless applications

Packet video transmission over wireless networks is expected to experience bursty packet losses due to noise, interference, multipath effects and the motion of mobile hosts. In order to achieve satisfactory end-to-end video quality in such an environment, we first demonstrate the necessity of adapting to both the source and channel dynamic information at the source encoding side using a combination of adaptive packetization and adaptive intra-updating. We then describe the implementation of an adaptive source encoder which can adaptively adjust its packetization scheme and intra-updating rate according to both the source motion information and channel feedback. Motion information is estimated by an exponential weighted moving average (EWMA) approach and channel feedback is provided by RTCP return packets. Finally, we demonstrate the advantages of exploiting source/channel dynamic information through selected simulation results. However, we show that imperfect channel feedback can sometimes be detrimental to system performance.