The first 21 lines of a television field in the analog format, normally invisible to the viewer, where closed-caption data and other information are carried.
The first 21 lines of the 525 horizontal line standard television picture. These 21 lines do not contain picture information and can be used to convey ancillary information, such as test signals and/or data.
(VBI) - The 21 lines between TV frames, transmitted, like the frames, at a rate of 30 times per second. The se lines are used for auxiliary information, including teletext, closed captions, and test signals.
The time period in which a television signal is not visible on the screen because of the vertical retrace (the repositioning to top of screen to start a new scan). Data services can be transmitted using a portion of this signal.
A period in which the electron beam in display is blanked out while it travels from the bottom of the screen to the top.
The period of time between television pictures, which is visible as a black bar when the picture rolls. The VBI contains signals that allow receivers to keep the picture stable and has additional signal capacity that can be used to carry closed captioning information, test, cue and control signals, and other data services.
The horizontal black bar visible on a TV picture when the vertical-hold control is adjusted so that the picture "rolls" off center. The VBI consists of 21 lines and, because each line arrives at two 1/60-second intervals, totals 42 of the 525 lines available with the NTSC system. The VBI allows a video-picture scan line to return to the starting point at the next picture frame (the first nine lines contain the signal pulses that synchronize picture transmission) and also is useful for carrying specially encoded data to multiple recipients in the video distribution chain.
The blanking portion at the beginning of each field. It contains the equalizing pulses, the vertical sync pulses, and vertical interval test signals (VITS). Also the period when a scanning process is moving from the lowest horizontal line back to the top horizontal line.
The top of the video, unseen on most TVs, which contains captioning on its 21st line. It can contain other data streams as well.
Unused lines in each field of a TV signal. Some of these lines may be used for captions and specialized signal and cable service.
The vertical blanking interval (VBI), also known as the vertical interval or VBLANK, is the time found between the last line of one frame or field and the beginning of the next. It is present in analog television, VGA, and DVI signals. During this time, the data that is transmitted is not displayed on the screen.
