![]() ![]() Not to be confused with on-screen display. ![]() Video overlay is any technique used to display a video window on a computer display while bypassing the chain of CPU to graphics card to computer monitor. This is done in order to speed up the video display, and it is commonly used, for example, by TV tuner cards and early 3D graphics accelerator cards. A video overlay device can be connected between the graphics card analog VGA output and the monitor's input forming a " VGA passthrough".Various methods to achieve video overlay are in use: The term is also used to describe the annotation or inclusion of interactivity on online videos, such as overlay advertising (mid-roll overlay). Screencast-O-Matic, also known as ScreenPal, is an online screen capture tool that allows you to draw shapes and graphics to life while recording for free. The device modifies the VGA signal and inserts the analog video signal overlay into the picture the rest of the screen is filled by the signal coming from the graphics card. Best for those looking for an affordable video editor. The driver software informs the video overlay device about the desired position of the video window on screen. Some video overlay devices write the digital video signal directly into the graphics card's video memory or provide it to the graphics card's RAMDAC.Because of the much greater processing power of modern graphics cards, and the awkwardness of adding additional analog hardware signal processing path, this method is now little used. ![]()
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