one embodiment of the present invention provides a method that facilitates compression of video data in a computer system by performing the time - consuming task of computing the difference between successive frames of video data independently from the central processing unit . this frees the often - overburdened central processing unit from performing this time - consuming compression operation and can thereby improve the handling of video data . thus , one embodiment of the present invention can be characterized as a method for compressing video data in a computer system . this method includes receiving a stream of data from a current video frame in the computer system . it also includes computing a difference frame from the current video frame and a previous video frame “ on - the - fly ” as the current video frame streams into the computer system . the method additionally includes storing the difference frame in a memory in the computer system .