Patent ID: 7408991

Claim:
A method comprising: transforming information about the spatial frequency distribution of a video data block into pixel values; generating, prior to said transformation, a first reference value representing the variations in information about spatial frequency distribution within the block; generating, after said transformation, a second reference value representing the abruptness of variation in certain information between the block and at least one previously transformed video data block from a same frame as the block; comparing the first reference value to a certain first threshold value and the second reference value to a certain predetermined second threshold value; detecting an error in the block, as a response to either of the first and second reference values being greater than the first and respectively the second threshold value; dividing DCT coefficients of the block into at least two parts, wherein the coefficients of the first part are associated with higher frequencies than the coefficients of the second part; generating a first reference value from the coefficients of the first part; generating a first threshold value from the coefficients of a set of coefficients not belonging to the first part; forming at least two sets of DCT coefficients from the coefficients not belonging to the first part; generating a first reference value for each formed set of DCT coefficients; generating a corresponding first threshold value for each formed set of DCT coefficients; comparing, for each of the sets, the first reference value of the set with the first threshold value of the set; and detecting an error in the block, as a response to any of the first reference values of the set being greater than the corresponding first threshold value of the set.