Vertical Blanking Interval: Difference between revisions

From LinuxTVWiki
Jump to navigation Jump to search
(import information from the "Teletext" article to create this page)
 
(last edit should have said "Text capture" article, not "teletext"; Some reworking of the description; add links)
Line 1: Line 1:
The Vertical Blanking Interval is an interval in a television signal that temporarily suspends transmission of the signal for the electron gun to move back up to the first line of the television screen to trace the next screen field. The vertical blanking interval can be used to carry data, since anything sent during the VBI would naturally not be displayed; various test signals, closed captioning, and other digital data can be sent during this time period.
The vertical blanking interval (VBI) is a very brief period of time during some video signals through which transmission of visual field/frame information is temporarily suspended. This interval corresponds to the time that was required for the electron guns of old CRT display technologies to move their beam's position back up to the left side of the first line of the television/display screen in order to begin to trace out the next screen field. Though this requirement is no longer relevant to modern digital display technologies, the VBI itself has been retained in video signals for compatibility purposes.

As nothing is displayed onscreen during the VBI, this portion of the video signal can be used for the purposes of carrying other data information. Indeed, various test signals, [[Closed Captioning]], [[Teletext]], copy-protection mechanisms, and various forms of digital data all exploit the opportunity afforded by the VBI

==External Links==
* [[Wikipedia:Vertical blanking interval|Wikipedia'a VBI article]]

Revision as of 23:43, 17 October 2011

The vertical blanking interval (VBI) is a very brief period of time during some video signals through which transmission of visual field/frame information is temporarily suspended. This interval corresponds to the time that was required for the electron guns of old CRT display technologies to move their beam's position back up to the left side of the first line of the television/display screen in order to begin to trace out the next screen field. Though this requirement is no longer relevant to modern digital display technologies, the VBI itself has been retained in video signals for compatibility purposes.

As nothing is displayed onscreen during the VBI, this portion of the video signal can be used for the purposes of carrying other data information. Indeed, various test signals, Closed Captioning, Teletext, copy-protection mechanisms, and various forms of digital data all exploit the opportunity afforded by the VBI

External Links