Pre-processing of video data

A method comprising:

• obtaining, with a video processing apparatus, video frames, the video frames including macroblocks;
• comparing, with the video processing apparatus, a current macroblock in a current frame stored in a current frame buffer with a corresponding reference macroblock in a reference frame stored in a reference frame buffer;
• setting, with the video processing apparatus, a flag value for said current macroblock if the comparing indicates that the current macroblock and the corresponding reference macroblock are substantially different;
• creating, with the video processing apparatus, a residual macroblock by calculating a respective difference value for all pixels in a macroblock by respectively subtracting all pixels in the current macroblock from all corresponding pixels in the corresponding reference macroblock;
• respectively dividing, with the video processing apparatus, the residual macroblock into subsets Dn, wherein n denotes an index of a subset;
• and
• executing, with the video processing apparatus, a sub-comparison for each Dn by comparing a multiplication of a sum of values in Dn and a weighting function (w) with a threshold value Tn,
• wherein the current macroblock and the corresponding reference macroblock are determined as substantially different if the multiplication is greater than Tn for one or more of said subsets.