S frame design for multiple description video coding

Multiple description (MD) video coding generates several descriptions so that any subset of descriptions can reconstruct video, which provides much error resilience. But most of the current MD video coding schemes are for two descriptions and for "on-off" channels, which is not suitable for packet-loss networks. This paper proposes a scheme to enhance the error resilience of traditional MD video coding in such environments, by periodically inserting S frames, a kind of switching frame, in the video stream to make the good description recover the \´bad\´ description, with very small redundancy. This proves to perform well in packet lossy networks especially at lower packet loss rate.