An apparatus for generating a quality-scalable video data stream (36) is described which comprises means (42) for coding a video signal (18) using block-wise transformation to obtain transform blocks (146, 148) of transformation coefficient values for a picture (140) of the video signal, a predetermined scan order (154, 156, 164, 166) with possible scan positions being defined among the transformation coefficient values within the transform blocks so that in each transform block, for each possible scan position, at least one of the transformation coefficient values within the respective transform block belongs to the respective possible scan position; and means (44) for forming, for each of a plurality of quality layers, a video sub-data stream (30; 28, 30) containing scan range information indicating a sub-set of the possible scan positions, and transform coefficient information on transformation coefficient values belonging to the sub-set of possible scan positions such that the sub-set of each quality layer comprises at least one possible scan position not comprised by the sub-set of any other of the plurality of quality layers.