A method includes reading a composite video descriptor data structure and a plurality of window descriptor data structures. The composite video descriptor data structure defines a width and height of a composite video frame and each window descriptor data structure defines the starting X and Y coordinate, width and height of each constituent video window to be rendered in the composite video frame. The method further includes determining top and bottom Y coordinates for each constituent video window, as well as determining left and right X coordinates for each constituent video window. The method also includes dividing each constituent video window using the top and bottom Y coordinates to obtain Y-divided sub-windows, dividing each Y-divided sub-window using left and right X coordinates to obtain X and Y divided sub-windows, and storing X, Y coordinates of opposing corners of each X and Y divided sub-window in the storage device.