title: It is possible to programmatically send information on the R/G/B data pins to a VGA monitor during the Vertical Blanking Interval (VBI)?
body: <p>I'm trying to send information like close captioning to a special VGA monitor that can read the RGB data lines during the BVI. The data is used for synchronization with other devices.</p>
  
  <p>I cannot find information regarding any Windows API to do so. Is there any OS that has these services? Is there any support in the standard video boards to do this kind of tweaking?</p>
  
  <p>The closes I get is some DirectX API functions that can parse "Line 21" data from DVD streams but nothing to encode "Line 21" data to be send out of the VGA connector.</p>