(8-446) + xEk - - 1, yP * yEk =p'i (8-447) Otherwise (verticalEdgeFlag is equal to 0), [xP+xEk,yP+dy*(yEk+i)-(yEk%2)]=g (8-448) s'[ xP + xEk, yP + dy*(yEk-i-1)-(yEk%2)]= p' (8-449) 8.7.2 Filtering process for a set of samples across a horizontal or vertical block edge Inputs to this process are the input sample values Pi and qi with i in the range of 0..3 of a single set of samples across an edge that is to be filtered, chromaEdgeFlag, and verticalEdgeFlag. Outputs of this process are the filtered result sample values p'i and q'i with i in the range of 0..2. The content dependent boundary filtering strength variable bS is derived as follows: If chromaEdgeFlag is equal to 0, the derivation process for the content dependent boundary filtering strength specified in clause 8.7.2.1 is invoked with Po, qo, and verticalEdgeFlag as input, and the output is assigned to bS. Otherwise (chromaEdgeFlag is equal to 1), the bS used for filtering a set of samples of a horizontal or vertical chroma edge is set equal to the value of bS for filtering the set of samples of a horizontal or vertical luma edge, respectively, that contains the luma sample at location ( SubWidthC * X, SubHeightC* ) inside the luma array of the same field, where (x,y) is the location of the chroma sample qo inside the chroma array for that field. Let filterOffsetA and filterOffsetB be the values of FilterOffsetA and FilterOffsetB as specified in clause 7.4.3 for the slice that contains the macroblock containing sample qo. Let qPp and qP be variables specifying quantisation parameter values for the macroblocks containing the samples Po and qo, respectively. The variables qPz (with Z being replaced by p or q) are derived as follows: Rec. ITU-T H.264 (01/2012) If chromaEdgeFlag is equal to 0, the following applies: If the macroblock containing the sample Zo is an I PCM macroblock, qP is set to 0. Otherwise (the macroblock containing the sample Zo is not an PCM macroblock), qP2 is set to the value of QPy of the macroblock containing the sample Zo. Otherwise (