Generation and use of masks in mpeg video encoding to indicate non-zero entries in transformed macroblocks

Abstract From the Canadian patent

During Motion Picture Experts Group (MPEG) video encoding a twodimensional discrete cosine transform (DCT) is performed on data representing an, original image. The resulting coefficients are then quantized which typically , results, in many zero coefficients. Because of the nature of most video data most , higher-, order coefficients are typically zero and the lower-order coefficients (i.e. those grouped towards the upper left of the matrix) are more likely to be non-zero. To, reduce the lengths of runs among the lower-order coefficients the , coefficients can, be encoded in a zig-zag pattern. In one embodiment the zig-zag pattern is, maintained and one or more masks are generated based …