Abstract: An in-loop deblocking-filtering method applied to a video CODEC is provided. The method includes steps of: receiving a macroblock of pixel values outputted from a motion-compensating unit; dividing the macroblock of pixel values into a plurality of block of pixel values, and executing a data-transpose procedure to the plurality of blocks of pixel values; storing the plurality of block of pixel values, which are processed by the data-transpose procedure, in a memory buffer; executing a horizontal deblocking-filtering procedure to the macroblock of pixel values, which are stored in the memory buffer, for updating a portion of the pixel values in the macroblock; executing the data-transpose procedure to the plurality of block of pixel values stored in the memory buffer; and executing a vertical deblocking-filtering procedure to the macroblock of pixel values, which are stored in the memory buffer, for updating a portion of the pixel values in the macroblock.