what is overlay ? Is it a function of graphic card or a function of video capture card or both? Someone told me : overlay means transfering video from capture card directly to video memory without cpu's involvement. Then according to this explaintion ,it should be the function of both. But from doc for SDL, I can also see yuvoverlay api. Does it mean without capture card ,SDL still can provide the overlay function. >From this point, overlay should be the function of video card . Does overlay means DMA between capture card and video card or some color space conversion by video card ? who can give me a answer ? Any help will be nice ,thanks in advance! __________________________________________________ Do You Yahoo!? Try FREE Yahoo! Mail - the world's greatest free email! http://mail.yahoo.com/