the current macroblock with CurrMbAddr. mbAddrA, mbAddrB, mbAddrC, and mbAddrD have identical values regardless whether the current macroblock is the top or the bottom macroblock of a macroblock pair. Rec. ITU-T H.264 (01/2012) mbAddrD mbAddrB mbAddrC mbAddrA CurrMbAddr or CurrMbAddr Figure 6-13 - Neighbouring macroblocks for a given macroblock in MBAFF frames Input to the process in clause 6.4.8 is mbAddrA = 2 * ( CurrMbAddr / 2 - and the output is whether the macroblock mbAddrA is available. In addition, mbAddrA is marked as not available when ( CurrMbAddr / 2 ) % PicWidthInMbs is equal to 0. Input to the process in clause 6.4.8 is mbAddrB = 2 * CurrMbAddr / - PicWidthInMbs ) and the output is whether the macroblock mbAddrB is available. Input to the process in clause 6.4.8 is mbAddrC = 2 * ( CurrMbAddr/ PicWidthInMbs + 1) and the output is whether the macroblock mbAddrC is available. In addition, mbAddrC is marked as not available when ( CurrMbAddr / 2 + 1 % % PicWidthInMbs is equal to 0. Input to the process in clause 6.4.8 is mbAddrD = 2* CurrMbAddr / 2 - PicWidthInMbs - 1) and the output is whether the macroblock mbAddrD is available. In addition, mbAddrD is marked as not available when ( CurrMbAddr/ 2) % PicWidthInMbs is equal to 0. 6.4.11 Derivation processes for neighbouring macroblocks, blocks, and partitions Clause 6.4.11.1 specifies the derivation process for neighbouring macroblocks. Clause 6.4.11.2 specifies the derivation process for neighbouring 8x8 luma blocks. Clause 6.4.11.3 specifies the derivation process for neighbouring 8x8 chroma blocks for ChromaArrayType equal to 3. Clause 6.4.11.4 specifies the derivation process for neighbouring 4x4 luma blocks. Clause 6.4.11.5 specifies the derivation process for neighbouring 4x4 chroma blocks. Clause 6.4.11.6 specifies the derivation process for neighbouring 4x4 chroma blocks for ChromaArrayType equal to 3. Clause 6.4.11.7 specifies the derivation process for neighbouring partitions. Table 6-2 specifies the values for the difference of luma location 