he current macroblock prediction mode is not equal to Intra 16x16, the variable LumaLevel4x4 contains the levels for the luma transform coefficients. For a 4x4 luma block indexed by luma4x4BlkIdx = 0..15, the following ordered steps are specified: The inverse scanning process for 4x4 transform coefficients and scaling lists as specified in clause 8.5.6 is invoked with LumaLevel4x4[ luma4x4BlkIdx ] as the input and the two-dimensional array c as the output. The scaling and transformation process for residual 4x4 blocks as specified in clause 8.5.12 is invoked with C as the input and r as the output. When TransformBypassModeFlag is equal to 1, the macroblock prediction mode is equal to Intra_4x4, and Intra4x4PredMode[ luma4x4BlkIdx ] is equal to 0 or 1, the intra residual transform-bypass decoding process as specified in clause 8.5.15 is invoked with nW set equal to 4, nH set equal to 4, horPredFlag set equal to Intra4x4PredMode[ luma4x4BlkIdx ], and the 4x4 array r as the inputs, and the output is a modified version of the 4x4 array r. The position of the upper-left sample of a 4x4 luma block with index luma4x4BlkIdx inside the macroblock is derived by invoking the inverse 4x4 luma block scanning process in clause 6.4.3 with luma4x4BlkIdx as the input and the output being assigned to xO, yO ). The 4x4 array u with elements Uij for i, j = 0..3 is derived as: (8-299) When TransformBypassModeFlag equal to 1, the bitstream shall not contain data that result in a value of Uij as computed by Equation 8-299 that is not equal to predL + + Iii. The picture construction process prior to deblocking filter process in clause 8.5.14 is invoked with u and luma4x4BlkIdx as the inputs. 8.5.2 Specification of transform decoding process for luma samples of Intra_16x16 macroblock prediction When the current macroblock prediction mode is equal to Intra_16x16, the variables Intra16x16DCLevel and Intral6x16ACLevel contain the levels for the luma transform coefficients. The transform coefficient decoding proceeds in the following ordered