An apparatus adapted to generate a plurality of transform coefficients for coding a frame or portion thereof comprising: a media encoder coupled to a data interface adapted to receive a frame or portion thereof, said media encoder is adapted to: iteratively subdivide each of a plurality of blocks partitioned in a frame or portion thereof during each of a plurality of iterations a subdivided block of said plurality of blocks is processed by: selecting a rotational symmetry mask fulfilling an efficiency measure for coding said subdivided block, wherein said rotational symmetry mask is selected from a plurality of rotational symmetry masks which define a plurality of different rotational symmetries in a multi dimensional space, each of which has the size and the shape as said subdivided block, by computing the number of encoded bits for the subdivided block divided in accordance with each of said plurality of rotational symmetry masks, wherein the rotational symmetry mask corresponding to the lowest number of encoded bits is selected, wherein fulfilling the efficiency measure indicates that applying the selected rotational symmetry mask on said subdivided block results in a lower number of bits than not applying any rotational symmetry mask; when said efficiency measure is fulfilled: split said subdivided block into two complementary portions based on said rotational symmetry mask, generate a pair of rotational symmetry blocks each based on one of said two complementary portions and a portion added to form each of the rotational symmetry blocks having the same size and shape, wherein the portion added is a 2D mirror of the one of said two complementary portions; and compute a plurality of transform coefficients from said pair of rotational symmetry blocks. iteratively subdivide each of a plurality of blocks partitioned in a frame or portion thereof during each of a plurality of iterations a subdivided block of said plurality of blocks is processed by: selecting a rotational symmetry mask fulfilling an efficiency measure for coding said subdivided block, wherein said rotational symmetry mask is selected from a plurality of rotational symmetry masks which define a plurality of different rotational symmetries in a multi dimensional space, each of which has the size and the shape as said subdivided block, by computing the number of encoded bits for the subdivided block divided in accordance with each of said plurality of rotational symmetry masks, wherein the rotational symmetry mask corresponding to the lowest number of encoded bits is selected, wherein fulfilling the efficiency measure indicates that applying the selected rotational symmetry mask on said subdivided block results in a lower number of bits than not applying any rotational symmetry mask; when said efficiency measure is fulfilled: split said subdivided block into two complementary portions based on said rotational symmetry mask, generate a pair of rotational symmetry blocks each based on one of said two complementary portions and a portion added to form each of the rotational symmetry blocks having the same size and shape, wherein the portion added is a 2D mirror of the one of said two complementary portions; and compute a plurality of transform coefficients from said pair of rotational symmetry blocks. split said subdivided block into two complementary portions based on said rotational symmetry mask, generate a pair of rotational symmetry blocks each based on one of said two complementary portions and a portion added to form each of the rotational symmetry blocks having the same size and shape, wherein the portion added is a 2D mirror of the one of said two complementary portions; and compute a plurality of transform coefficients from said pair of rotational symmetry blocks. <EOS>