METHOD FOR USING A MEMORY DURING A SUB PICTURE DECODING PROCESS OF A DVD, SPECIFICALLY WITH REGARDS TO REDUCING SIZE OF AN OSD MEMORY DURING THE DECODING PROCESS BY USING FEATURES OF A SUB PICTURE CONSISTING OF BIT MAPS

摘要

PURPOSE: A method for using a memory during a sub picture decoding process of a DVD is provided to store Y coordinates values of the first sub picture, and to update into the Y coordinates values of the first sub picture when a sub picture decoding process is completed, thereby reducing size of an OSD memory without storing color and contrast values in the OSD memory. CONSTITUTION: A sub picture decoder decodes sub picture data(201), and initializes a variable 'n' to 2(202). The decoder stores color values of all pixels of X coordinates in an OSD memory(203), and decides whether any one of the pixels whose contrast values are not 0 exists(204). If not, the decoder overwrites color values of pixels whose Y coordinates are n+1 to color values of pixels whose Y coordinates are n(205), and decides whether any one of the pixels whose contrast values are not 0 exists(206). If not, the decoder increases 'n' by 1(207).