The Vertical Blanking Interval, often referred to as the VBI, is a small period of time between video frames, giving the display device opportunity to refresh its display ready for the next frame. During this period some broadcast video signals will encode and send additional data in the first 21 scan lines of a video frame.

In broadcast video, there is a small time delay between frames during which the display is refreshed for the next frame. This is called the Vertical Blanking Interval or VBI.

Broadcast video uses the VBI to encode data in the first 21 scan lines of a videoframe and send this data to the display device.

Videoport extensions allow you to divert data encoded during the VBI to a surface, allow you to bypass scaling of VBI data, and flip between vbi surfaces in a flipping chain. Once VBI memory is in a surface, you can directly access the surface memory as required.