 derived by p'[-1,-1]=(3p-1,-1]+p[-1,0]+2)>>2 (8-83) Otherwise (the sample p[ 0,-1] is marked as "not available for Intra_8x8 prediction" and the sample p[ -1,0] is marked as "not available for intra_8x8 prediction"), p'[-1,-1] is set equal to p -1, -1]. NOTE - When both samples p[ 0,-1] and p[ -1,0] are marked as "not available for Intra_8x8 prediction", the derived sample p'[ [-1,-1] is not used in the intra prediction process. Otherwise (the sample p[ 0,-1] is marked as "available for Intra 8x8 prediction" and the sample p[ -1,0] is marked as "available for Intra_8x8 prediction"), p'[-1, -1] is derived by p'[-1,-1]=(p[0,-1]+2*p[-1,-1]+p[-1,0]+2)>> (8-84) When all samples p[ (-1, y ] with y = 0..7 are marked as "available for Intra_8x8 prediction", the following applies: The value of p'[-1,0] is derived as follows: If p[-1,-1] is marked as "available for Intra_8x8 prediction", p'[ -1,0] is derived by p'[-1,0]=(p[-1,-1]+2*p[-1,0]+p[-1,1]+2)>>2 (8-85) Otherwise (p[-1,-1] is marked as "not available for Intra_8x8 prediction"), p'[ -1,0] is derived by p'[ -1,0]=(3*p[-1,0]+p[-1,1]+2)>>2 (8-86) The values of p'[ -1, y , with y = 1..6, are derived by p'[-1,y]=(p[-1,y-1]+2*p[-1,y]+p[-1,y+1]+2)>>2 (8-87) The value of p'[ [-1,7 is derived by p'[-1,7]=(p[-1,6]+3*p[-1,7]+2)>>2 (8-88) 8.3.2.2.2 Specification of Intra_8x8_Vertical prediction mode This Intra_8x8 prediction mode is invoked when Intra8x8PredMode[ luma8x8BlkIdx ] is equal to 0. This mode shall be used only when the samples p[ X, -1] with x=0..7 are marked as "available for Intra_8x8 prediction". Rec. ITU-T H.264 (01/2012) The values of the prediction samples pred8x8L X, y ], with X, y = 0..7, are derived by pred8x8L[x,y]=p[x,-1],withx, y = 0..7 (8-89) 8.3.2.2.3 Specification of Intra_8x8_Horizontal prediction mode This Intra_8x8 prediction mode is invoked when Intra8x8PredMode[ luma8x8BlkIdx ] is equal to 1. This mode shall be used only when the samples p[ (-1,y], with y = 0..7, are marked as "available for Intra_8x8 prediction". The values of the prediction sam