nd the current macroblock does not have mb_type equal to SI. Otherwise, the sample p[ X, y ] is marked as "available for Intra chroma prediction" and the value of the sample p[ X, y ] is derived as specified by the following ordered steps: The location of the upper-left luma sample of the macroblock mbAddrN is derived by invoking the inverse macroblock scanning process in clause 6.4.1 with mbAddrN as the input and the output is assigned to (xL, yL). The location ( xM, yM) of the upper-left chroma sample of the macroblock mbAddr is derived by: xM = (xL >>4) * MbWidthC (8-128) yM = ((yL>>4)* MbHeightC ) + (8-129) Depending on the variable MbaffFrameFlag and the macroblock mbAddrN, the sample value p[x,y] is derived as follows: If MbaffFrameFlag is equal to 1 and the macroblock mbAddrN is a field macroblock, x,y]=cSc[xM+ xW,yM+2*yW = ] (8-130) Otherwise (MbaffFrameFlag is equal to 0 or the macroblock mbAddrN is a frame macroblock), [x,y]=cSc[xM+xW,yM+yW] (8-131) Let predcl X, y ] with X = 0..MbWidthC - 1, y = 0..MbHeightC - 1 denote the prediction samples for the chroma block samples. Intra chroma prediction modes are specified in Table 8-5. Rec. ITU-T H.264 (01/2012) Table 8-5 - Specification of Intra chroma prediction modes and associated names intra_chroma_pred_mode Name of intra_chroma_pred_mode Intra_Chroma_DC (prediction mode) Intra_Chroma_Horizontal (prediction mode) Intra_Chroma_Vertical (prediction mode) Intra_Chroma_Plane (prediction mode) Depending on intra_chroma_pred_mode, one of the Intra chroma prediction modes specified in clauses 8.3.4.1 to 8.3.4.4 is invoked. 8.3.4.1 Specification of Intra_Chroma_DC prediction mode This Intra chroma prediction mode is invoked when intra_chroma_pred_modeisequal to 0. For each chroma block of 4x4 samples indexed by chroma4x4BlkIdx = 0..(1<< ChromaArrayType + 1 - 1, the following applies: The position of the upper-left sample of a 4x4 chroma block with index chroma4x4BlkIdx inside the current macroblock is derived by invoking the inverse 4x4 chroma block scanning proc