ients C1 are scaled using quantisation parameter QPc, and added to the transform coefficients of the prediction block CP with i, j=0..3 = except for the combination i = 0, j = 0 as follows: Cii = Cit's chroma4x4BlkIdx) + (Cii * LevelScale4x4( QPc % 6, i, ) * Aij) ( >> 10 (8-424) The resulting sum, cs, is quantised with a quantisation parameter QSc and with i, j = 0..3 except for the combination i = 0, j=0 = as follows. The derivation of coo( chroma4x4BlkIdx ) is described below in this clause. Cij( chroma4x4BlkIdx = Sign( * Abs( Ciis) * LevelScale2( QSc % 6, i, + <(14+QSc/6))))>>(15+QSc/6) (8-425) The scaling and transformation process for residual 4x4 blocks as specified in clause 8.5.12 is invoked with c( chroma4x4BlkIdx ) as the input and r as the output. Rec. ITU-T H.264 (01/2012) The 4x4 array u with elements Uij is derived by: Uij i, j = 0..3 (8-426) 10. The picture construction process prior to deblocking filter process in clause 8.5.14 is invoked with chroma4x4BlkIdx and u as the inputs. The derivation of the DC transform coefficient level coo( chroma4x4BlkIdx ) is specified as follows. The DC transform coefficients of the 4 prediction chroma 4x4 blocks of the current component of the macroblock are assembled into a 2x2 matrix with elements coo'(chroma4x4BlkIdx) and a 2x2 transform is applied to the DC transform coefficients as follows: (8-427) The chroma DC prediction residual transform coefficient levels, ChromaDCLevel[ iCbCr ][ k] with k = 0..3 are scaled using quantisation parameter QPc, and added to the prediction DC transform coefficients as follows: s=dcjp+(((ChromaDCLevel[iCbCr][j*2+i]*LevelScale4x4(QPc % 6, 0, 0) A00 << (QPc/6) with i,j=0,1 (8-428) The 2x2 array dcs, is quantised using the quantisation parameter QS as follows: Abs( dcj) *LevelScale2(QSc%6,0,0)+(1<<( 15 + QS(6))) 16 QSc / ith i,j=0,1 (8-429) The 2x2 array f with elements fij and i, j = 0..1 is derived as: (8-430) Scaling of the elements fij of f is performed as follows: LevelScale4x4( QSc % 6, 0, ) << ( QSc 6) >> 5 with i, 1 (8-43