maxW - 1 0..maxH - 1 CurrMbAddr CurrMbAddr mbAddrC mbAddrC + 1 not available not available maxW - mbAddrC + 1 2* yN mbAddrC mbAddrC mbAddrC mbAddrC + 1 0..maxH - 1 not available not available maxH - 1 not available not available The neighbouring luma location ( xW, yW) relative to the upper-left corner of the macroblock mbAddrN is derived as xW = ( NN + maxW) % maxW (6-36) yW = yM + maxH) % maxH (6-37) Rec. ITU-T H.264 (01/2012) 6.4.13 Derivation processes for block and partition indices Clause 6.4.13.1 specifies the derivation process for 4x4 luma block indices. Clause 6.4.13.2 specifies the derivation process for 4x4 chroma block indices. Clause 6.4.13.3 specifies the derivation process for 8x8 luma block indices. Clause 6.4.13.4 specifies the derivation process for macroblock and sub-macroblock partition indices. 6.4.13.1 Derivation process for 4x4 luma block indices Input to this process is a luma location ( xP, yP) relative to the upper-left luma sample of a macroblock. Output of this process is a 4x4 luma block index luma4x4BlkIdx. The 4x4 luma block index luma4x4BlkIdx is derived by luma4x4BlkIdx = 8 (yP/8) + 4 /8)+2*((yP%8)/4)+((xP%8)/4) (6-38) 6.4.13.2 Derivation process for 4x4 chroma block indices This clause is only invoked when ChromaArrayType is equal to 1 or 2. Input to this process is a chroma location (xP, yP ) relative to the upper-left chroma sample of a macroblock. Output of this process is a 4x4 chroma block index chroma4x4BlkIdx. The 4x4 chroma block index chroma4x4BlkIdx is derived by chroma4x4BlkIdx = 2* (yP/4) + xP / 4) (6-39) 6.4.13.3 Derivation process for 8x8 luma block indices Input to this process is a luma location ( xP, yP ) relative to the upper-left luma sample of a macroblock. Outputs of this process is an 8x8 luma block index luma8x8BlkIdx. The 8x8 luma block index luma8x8BlkIdx is derived by luma8x8BlkIdx = 2*(yP/8)+( xP (6-40) 6.4.13.4 Derivation process for macroblock and sub-macroblock partition indices Inputs to this process are: a luma location (xP, yP ) relative to the u