Platform SDK: Broadcast Architecture

V

VBI
See vertical blanking interval.
vertical blanking interval
(VBI) The time period in which a television signal is not visible on the screen because of the vertical retrace (that is, the repositioning to the top of the screen to start a new scan). Data services can be transmitted using a portion of this signal. In a standard NTSC signal, perhaps 10 scan lines are potentially available per channel during the VBI. Each scan line represents a data transmission capacity of about 9600 baud.
VGA
See Video Graphics Array.
Video control
An ActiveX control in Broadcast Architecture that applications use to control how the Video Access server presents audio and video streams. Unlike the Enhancement Video control, which displays video in enhancements, the Video control can be used in World Wide Web pages and stand-alone applications as well as in WebTV for Windows. In contrast, the Enhancement Video control can be used only in Hypertext Markup Language (HTML) pages displayed by WebTV for Windows. However, the Enhancement Video control automatically handles the connection between itself and WebTV for Windows, whereas the Video control does not. The Video control is provided with Broadcast Architecture.
Video Graphics Array
(VGA) A video standard created by IBM that supports several modes, including a graphics mode of 640 horizontal pixels by 480 vertical pixels with 2 or 16 simultaneous colors and a graphics mode of 320 horizontal pixels by 200 vertical pixels with 256 colors. The term VGA chip is often used generically to refer to a video controller chip.
virtual device driver
(VxD) A 32-bit, protected-mode driver that manages a system resource, such as a hardware device or installed software, so that more than one application can use the resource at the same time. VxD refers to a general virtual device driver — the x represents the type of device driver. For example, a virtual device driver for a display device is known as a VDD, a virtual device driver for a timer device is a VTD, a virtual device driver for a printer device is a VPD, and so on.
VxD
See virtual device driver.