Abstract
Method and apparatus for generating coded block pattern are provided herein. In the method, highpass coefficients after quantization are received, and the highpass coefficients includes a macroblock, which is divided into a plurality of blocks. Two-stage block lapped transform operation is performed upon the blocks, and different coded block patterns according to all possible highpass prediction directions are concurrently generated. After the two-stage block lapped transform operation, lowpass coefficients generated therefrom are used to select correct one of the highpass prediction directions, and the coded block pattern according to the correct highpass prediction direction is used for the highpass coefficients.