Abstract: A novel apparatus for and method of calculating the SAD values for half pixels is disclosed. The invention interpolates, in a serial fashion, half pixel values from full pixels contained in a search window. These half pixels ale then compared with pixels in a template macro block. The differences are then generated and accumulated in registers. The search window and template macro block pixels are shifted into FIFOs whereby a plurality of adders generates half pixel values. Latches are used to store and delay the half pixel values for input to a bank of subtractors. The subtractors calculate the differences between the interpolated half pixels and the template macro block pixels. The output of the subtractors are accumulated resulting in eight SAD values.

Abstract: An apparatus for processing sum of the absolute differences (SAD) is disclosed. A novel circuit is disclosed which eliminates the requirement of taking the absolute value of intermediate partial sum results. The absolute value function is only needed after the final summation stage. Subtraction units take the difference between each pair of values to be processed. The output of the subtraction units are input to a first level of two input summation units. If there is more than one summation unit in the first level, the output of these summation units are input to a second level of summation units. At each level half the number of units are required until a level is reached having only one unit. The absolute value of the last unit is then taken which forms the final SAD result. Each summation unit performs an addition on its two inputs while preserving the magnitude of their sum. Depending on the sign of one of the inputs, the two inputs are either added to each other or subtracted from each other.

Abstract: A novel apparatus for and method of reducing the memory bandwidth required to process data located in a window is disclosed. The data located in the window is processed against known template data in accordance with a predetermined function or matching criteria. The criteria could be the best match between data in a given window of data, termed the search window, and data contained in a smaller size template block. The data in the search window is divided into smaller sized blocks. The template block is compared against each block in the search window in order to determine a best match. The invention is described in the context of a motion estimator within a video compression system but is applicable to other areas as well. The invention utilizes a plurality of processing elements and FIFO arrays arranged in a linear array to reduce the memory bandwidth required to process the data within the search window.