 each of the Cb and Cr blocks separately. The process specified in this clause is invoked for each Cb and Cr block. Depending on the macroblock prediction mode, the following applies: If the macroblock prediction mode is equal to Intra_4x4, the following applies: The same process described in clause 8.3.1 is also applied to Cb or Cr samples, substituting luma with Cb or Cr, substituting luma4x4BlkIdx with cb4x4BlkIdx or cr4x4BlkIdx, substituting pred4x4 with pred4x4 or pred4x4cr, and substituting BitDepthy with BitDepthc. The output variable intra4x4PredMode[luma4x4BlkIdx] from the process described in clause 8.3.1.1 is also used for the 4x4 Cb or 4x4 Cr blocks with index luma4x4BlkIdx equal to index cb4x4BlkIdx or cr4x4BlkIdx. The process to derive prediction Cb or Cr samples is identical to the process described in clause 8.3.1.2 and its subsequent subclauses when substituting luma with Cb or Cr, substituting pred4x4 with pred4x4 or pred4x4cr and substituting BitDepthy with BitDepthc. Otherwise, if the macroblock prediction mode is equal to Intra_8x8, the following applies: The same process described in clause 8.3.2 is also applied to Cb or Cr samples, substituting luma with Cb or Cr, substituting luma8x8BlkIdx with cb8x8BlkIdx or cr8x8BlkIdx, substituting pred8x8 with pred8x8cb or pred8x8cr: and substituting BitDepthy with BitDepthc. The output variable Intra8x8PredMode[luma8x8BlkIdx] from the process described in clause 8.3.2.1 is used for the 8x8 Cb or 8x8 Cr blocks with index luma8x8BlkIdx equal to index cb8x8BlkIdx or cr8x8BlkIdx. Rec. ITU-T H.264 (01/2012) The process to derive prediction Cb or Cr samples is identical to the process described in clause 8.3.2.2 and its subsequent subclauses when substituting luma with Cb or Cr, substituting pred8x8L with pred8x8cb or pred8x8cr and substituting BitDepthy with BitDepthc. Otherwise (the macroblock prediction mode is equal to Intra_16x16), the same process described in clause 8.3.3 and in the subsequent subclauses 8.3.3.1 to 8.3.3.4 is also applied to Cb or Cr