Packet loss resisilent H.263+ compliant video coding

This paper considers the problem of real-time point to point video transmission over the public Internet. A set of techniques in the direction of packet loss resilience of video compressed streams is presented. Aiming at a best trade-off between compression efficiency and packet loss resilience, a procedure for adapting the video coding modes and quantizer parameters to varying network characteristics is introduced. The network adaptive coding modes and quantizers selection is based on a rate-distortion procedure with global distortion metrics incorporating channel characteristics under the form of a packet loss model. The method has been implemented in a H.263+ software video encoder. As a second step, the coding mode selection strategy is refined by exploiting feedback information which consists in indicating lost video packets. We show that exploiting this knowledge of the channel state allows to significantly improve the robustness of H.263+ video streams in a packet loss prone environment.