Detection and Concealment of Transmission Errors in MPEG-4 Images

For entropy-coded MPEG-4 images, a transmission error in a codeword may cause the underlying codeword and its subsequent codewords within a video packet to be misinterpreted, resulting in great degradation of the received MPEG-4 images. Here a transmission error may be a single-bit error or a burst error. In this study, a postprocessing approach to detection and concealment of transmission errors in MPEG-4 images is proposed. In this study, transmission errors within a video packet of an MPEG-4 image bit-stream are detected by means of two successive procedures: (1) whether the video packet is corrupted or not is determined by checking a set of error-checking conditions, and then (2) the precise location (block-based) of the first transmission error (the first corrupted block) within the corrupted video packet is verified by using a backtracking procedure. To recover the corrupted shape data, the error concealment approach to the shape data of intra-coded IVOPs proposed in [4] is adopted, and an error concealment approach to the shape data of inter-coded P- and BVOPs is proposed in this study. To recover the corrupted texture data, several existing and proposed concealment techniques are employed together to generate a set of possible concealment candidates for a corrupted texture block. Then, an objective cost function is proposed here to determine the 'best'texture error concealment candidate among the set of generated candidates as the concealed texture block for the corrupted texture block. Based on the simulation results obtained in this study, the proposed approach can recover high-quality MPEG-4 images from the corresponding corrupted MPEG-4 images. This shows the feasibility of the proposed approach.