POCS based error concealment for packet video

Summary form only given. This paper proposes a new error concealment algorithm for packet video, effectively eliminating error propagation effects. Most standard video codecs use motion compensation to remove temporal redundancy. With such motion compensated interframe processing, any packet loss may generate serious error propagation over more than 10 consecutive frames. This kind of error propagation leads to perceptually annoying artifacts. Thus, proper error concealment algorithms need to be used to reduce this effect. The proposed algorithm adopts a one pixel block overlap coding structure to solve the error propagation problem. If no packet loss occurs, the decoded pixel intensities on the overlap areas should be consistent (with small differences caused by quantization error). When a packet loss occurs, the corresponding reconstructed frame and any frames referring to it are all damaged. Such damage causes inconsistent pixel intensities on the overlap areas of damaged frames. The proposed error concealment method poses the packet loss recovery problem as one of parameter estimation. Lost transform coefficients are estimated by the method of projection onto convex sets (POCS). The estimation is performed in a manner that maximizes the consistency of pixel intensities in the overlap areas of the reconstructed frames. Experimental results (using a modified version of CCITT H.261) show that it can have good error concealment results even when the damaged frame loses all the DCT coefficients.