a block containing the sample Po contains non-zero transform coefficient levels, transform_size_8x8_flag is equal to 0 for the macroblock containing the sample Po and the 4x4 luma transform block associated with the 4x4 luma block containing the sample Po contains non-zero transform coefficient levels, transform_size_8x8_flag is equal to 1 for the macroblock containing the sample qo and the 8x8 luma transform block associated with the 8x8 luma block containing the sample qo contains non-zero transform coefficient levels, transform_size_8x8_flag is equal to 0 for the macroblock containing the sample qo and the 4x4 luma transform block associated with the 4x4 luma block containing the sample qo contains non-zero transform coefficient levels. Otherwise, if any of the following conditions are true, a value of bS equal to 1 is the output: mixedModeEdgeFlag is equal to 1, - mixedModeEdgeFlag is equal to 0 and for the prediction of the macroblock/sub-macroblock partition containing the sample Po different reference pictures or a different number of motion vectors are used than for the prediction of the macroblock/sub-macroblock partition containing the sample qo, NOTE 1 - The determination of whether the reference pictures used for the two macroblock/sub-macroblock partitions are the same or different is based only on which pictures are referenced, without regard to whether a prediction is formed using an index into reference picture list 0 or an index into reference picture list 1, and also without regard to whether the index position within a reference picture list is different. NOTE 2 - The number of motion vectors that are used for the prediction of a macroblock partition with macroblock partition index mbPartIdx, or a sub-macroblock partition contained in this macroblock partition, is equal to PredFlagL0[ mbPartIdx ] + PredFlagL1[ mbPartIdx ]. mixedModeEdgeFlag is equal to 0 and one motion vector is used to predict the macroblock/sub-macroblock partition containing the sample Po and one motion vector is used to pre