Patent ID: 6594790
Filing Date: 2003-07-15
Classification: H04N

Abstract:
A method of concealing errors in a system that divides data into frames, divides the frames into blocks, and codes and decodes at least some of the blocks by intra-frame coding, these blocks being referred to as intra-blocks, comprising the steps of:(a) decoding each coded intra-block to obtain an AC component and a DC component; (b) detecting decoding errors in said step (a); (c) testing at least one of the following conditions A to D, when an erroneous intra-block is detected in said step (b), condition A being that the DC component of the erroneous intra-block has a value within a predicted range, condition B being that the erroneous intra-block has a motion vector outside an acceptable range, the motion vector being obtained by interpolation, condition C being that the motion vector of the erroneous intra-block changes by an unacceptable amount, as compared with a preceding frame, and condition D being that said intra-frame coding was selected for the erroneous intra-block in preference to another coding method, instead of being forced; (d) replacing the erroneous intra-block with its DC component, if all of the conditions tested in said step (c) are satisfied; and (e) replacing the erroneous intra-block with decoded data from the preceding frame, if at least one of the conditions-tested in said step (c) is not satisfied.