Patent ID: 7509553

Claim:
A video-conferencing system, comprising: a decoder; an encoder connected to the decoder by a network; a packet loss detection mechanism co-located with the decoder, the packet loss detection mechanism configured to detect a lost packet and to transmit one of a packet loss notification message and a lost packet identification message; and one of a sustained packet loss detection mechanism co-located with one of the encoder and the packet loss detection mechanism, the sustained packet loss detection mechanism configured to receive the packet loss notification message and to inform the encoder that the packet loss notification message indicates a presence of one of a first and a second predetermined packet loss scenario, and an error concealment device co-located with the decoder and connected to the packet loss mechanism, the error concealment device configured to replace motion vector data lost from a current frame with motion vector data from a previous frame in response to the lost packet identification message; wherein the encoder is further configured to determine one of a reliability of a reference block and a change in a reference block mean value; wherein the encoder is configured to determine a reliability of a reference block on the basis of a period since the reference block was last updated as INTRA; and wherein the encoder is configured to determine a reliability R n of a reference block in a frame n is determined as follows: R n =1-p for INTRA blocks; R n =(1-p) R n-1 for INTER blocks with non-zero difference signal; and R n =R n-1 for INTER blocks with zero difference signals, where p is a packet loss probability and R n-1 is one of a reliability of a same block in a previous frame and an expression dependent on a reliability of neighbor blocks that includes non-zero motion vectors effects.