 macroblock above-left of the current macroblock. Figure 6-12 shows the relative spatial locations of the macroblocks with mbAddrA, mbAddrB, mbAddrC, and mbAddrD relative to the current macroblock with CurrMbAddr. Rec. ITU-T H.264 (01/2012) mbAddrD mbAddrB mbAddrC mbAddrA CurrMbAddr Figure 6-12 - Neighbouring macroblocks for a given macroblock Input to the process in clause 6.4.8 is mbAddrA = CurrMbAddr - 1 and the output is whether the macroblock mbAddrA is available. In addition, mbAddrA is marked as not available when CurrMbAddr % Pic eWidthInMt is equal to 0. Input to the process in clause 6.4.8 is mbAddrB = CurrMbAddr - PicWidthInMbs and the output is whether the macroblock mbAddrB is available. Input to the process in clause 6.4.8 is mbAddrC = CurrMbAddr - PicWidthInMbs + 1 and the output is whether the macroblock mbAddrC is available. In addition, mbAddrC is marked as not available when ( CurrMbAddr + 1) % PicWidthInMbs is equal to 0. Input to the process in clause 6.4.8 is mbAddrD = CurrMbAddr - PicWidthInMbs - 1 and the output is whether the macroblock mbAddrD is available. In addition, mbAddrD is marked as not available when CurrMbAddr Pic WidthInMbs is equal to 0. 6.4.10 Derivation process for neighbouring macroblock addresses and their availability in MBAFF frames This process can only be invoked when MbaffFrameFlag is equal to 1. The outputs of this process are: mbAddrA: the address and availability status of the top macroblock of the macroblock pair to the left of the current macroblock pair, mbAddrB: the address and availability status of the top macroblock of the macroblock pair above the current macroblock pair, mbAddrC: the address and availability status of the top macroblock of the macroblock pair above-right of the current macroblock pair, mbAddrD: the address and availability status of the top macroblock of the macroblock pair above-left of the current macroblock pair. Figure 6-13 shows the relative spatial locations of the macroblocks with mbAddrA, mbAddrB, mbAddrC, and mbAddrD relative to 