o this process are two (PicWidthInSamplesc)x(PicHeightInSamplesc) arrays cScb and cScr containing constructed chroma samples prior to the deblocking filter process of neighbouring macroblocks. Outputs of this process are Intra prediction chroma samples for the current macroblock predcb[ X, y ] and predcr[ X, y ]. Depending on the value of ChromaArrayType, the following applies: Rec. ITU-T H.264 (01/2012) If ChromaArrayType is equal to 3, the Intra prediction chroma samples for the current macroblock predcb[ X, y ] and predcr[ X, y ] are derived using the Intra prediction process for chroma samples with ChromaArrayType equal to 3 as specified in clause 8.3.4.5. Otherwise (ChromaArrayType is equal to 1 or 2), the following text specifies the Intra prediction chroma samples for the current macroblock predcb[ X, y ] and predcr[ X, y ]. Both chroma blocks (Cb and Cr) of the macroblock use the same prediction mode. The prediction mode is applied to each of the chroma blocks separately. The process specified in this clause is invoked for each chroma block. In the remainder of this clause, chroma block refers to one of the two chroma blocks and the subscript C is used as a replacement of the subscript Cb or Cr. The neighbouring samples p[ X, y ] that are constructed chroma samples prior to the deblocking filter process, with X = -1, y 1..MbHeightC - 1 and with X = )..MbWidthC - 1, y=1- are derived as specified by the following ordered steps: 1. The derivation process for neighbouring locations in clause 6.4.12 is invoked for chroma locations with (x,y) assigned to (xN, yN ) as input and mbAddrN and (xW, yW) as output. 2. Each sample p[ X, y ] is derived as follows: If any of the following conditions are true, the sample p[ X, y ] is marked as "not available for Intra chroma prediction": mbAddrN is not available, the macroblock mbAddrN is coded in an Inter macroblock prediction mode and constrained_intra_pred_flag is equal to 1, the macroblock mbAddrN has mb_type equal to SI and constrained_intra_pred_flag is equal to 1 a