1. A block transform-based method of decoding a compressed bitstream containing digital media data, the method comprising: iteratively for each of a plurality of successive coded blocks in order in the compressed bitstream, the blocks having a plurality of entropy encoded coefficient values: entropy decoding coefficients for a current one of the plurality of successive coded blocks in the compressed bitstream; arranging the decoded coefficient values for the current block into a block structure having a plurality of locations according to a scan order; analyzing the statistical incidence of occurrence of coefficient values at the locations across the block structure; updating a set of cumulative statistics of the occurrence of coefficient values at the locations, the cumulative statistics accounting for the occurrence of coefficient values at the locations from any previously iterated ones of the plurality of successive coded blocks; and adapting the scan order according to said updated cumulative statistics, wherein the coefficient values accounted for by the cumulative statistics are non-zero coefficient values, wherein the adapting comprises exchanging the scan order of a first location with the scan order of a second location if the cumulative statistics indicate a higher occurrence of non-zero coefficient values at the second location than at the first location and not exchanging the scan order of the first location with the scan order of the second location if the cumulative statistics indicate a lower occurrence of non-zero coefficient values at the second location than at the first location, wherein the scan order of the second location is adjacent to the scan order of the first location, and wherein the method further comprises performing no further changes to the scan order of the second location for the current block if the scan order of the first location is exchanged with the scan order of the second location.