The dimensions and other parameters illustrated in FIG. 1 may be represented by the following symbols or variable names. scaled_base_left_offset=xorig scaled_base_top_offset=yorig scaled_base_right_offset=wenh???xorig???wextract scaled_base_bottom_offset=henh???yorig???hextract scaled_base_width=wextract scaled_base_height=hextract Inter-Layer Motion Prediction A given high layer macroblock can ex