Blanking Interval .

• Blanking Interval

https://store.theartofservice.com/the-blanking-interval-toolkit.html

Analog television Structure of a video signal

1 The front porch is a brief (about 1.5 microsecond) period inserted between the end of each transmitted line of picture and

the leading edge of the next line sync pulse. Its purpose was to allow voltage levels to stabilise in older televisions, preventing

interference between picture lines. The front porch is the first component of the horizontal

blanking interval which also contains the horizontal sync pulse and the back porch.


Analog television Vertical synchronization

1 Vertical synchronization (Also vertical sync or VSYNC) separates the video fields. In PAL and NTSC, the vertical sync pulse occurs within the vertical blanking interval. The vertical sync pulses are made by prolonging the

length of HSYNC pulses through almost the entire length of the scan

line.https://store.theartofservice.com/the-blanking-interval-toolkit.html

Analog television Vertical synchronization

1 Software such as Video Games and computer aided design (CAD) packages often allow vertical synchronization as an option,

because it delays the image update until the vertical blanking interval


Linux console - Control characters

1 The console also supports extended escape sequences, ANSI CSI Mode sequences, and DEC Private Mode

sequences. These extended sequences can control colors, visual effects like blinking,

underline, intensity and inverse video, bell tone frequency and duration, VESA screen blanking interval. Aside from the textual blanking, there is no known way to place

the VGA adapter into standby.


Digital Video Broadcasting - Content

1 Older technologies such as teletext (DVB-TXT) and vertical blanking interval data (DVB-VBI) are also

supported by the standards to ease conversion. However, for many

applications more advanced alternatives like DVB-SUB for

subtitling are available.


Seven-segment display - Implementations

1 To operate any particular segment of any digit, the controlling integrated circuit would turn on the cathode

driver for the selected digit, and the anode drivers for the desired segments; then after a short

blanking interval the next digit would be selected and new segments lit, in

a sequential fashionhttps://store.theartofservice.com/the-blanking-interval-toolkit.html

Macintosh 128K - Processor and memory

1 The 68000 and video controller take turns accessing DRAM every four CPU cycles during display of the frame buffer, while the 68000

has unrestricted access to DRAM during vertical and horizontal blanking intervals. Such an

arrangement reduces the overall performance of the CPU as much as 35% for most codes as the display logic often blocks the CPU's access to RAM. This made the machine appear to run slower than several of its competitors, despite

the nominally high clock rate.


Electronic program guide - Current applications

1 Older television IPGs like Guide Plus+ relied on analog technology (such as

the vertical blanking interval of analog television video signals) to

distribute listings data to IPG-enabled consumer receiving equipment


HDMI 1.4 - TMDS

1 During the Data Island period (which occurs during the horizontal and vertical blanking intervals), audio and auxiliary data are transmitted

within a series of packets


Composite video - Extensions to the composite video standard

1 Since TV screens hide the vertical blanking interval of a composite video signal and even

overscan|crop the edges of the picture, extensions have been implemented by taking advantage of these unseen parts of the signal. Examples of these extensions include teletext, closed captioning, digital information regarding the show title, transmitting a set of reference

colors that allows TV sets to automatically correct the hue mal-adjustments common with

the NTSC color encoding system, etc.


Atari 2600 - Hardware

1 After the controller scanned the last active line, a more leisurely vertical

blanking interval began, during which the game could process input and update the positions and states

of objects in the world


Digital Millennium Copyright Act - Effect on analog video equipment

1 The technology works by adding additional lines to the video signal. In the NTSC video standard, blank lines (vertical blanking intervals) that the

user cannot see are used for functions like closed captioning. Rovi Corporation uses these blank lines to

implement its ACP technology.


Digital Visual Interface - Technical overview

1 In single-link mode, the maximum pixel clock frequency is 165MHz that supports a maximum resolution of 2.75megapixels (including blanking

interval) at 60Hz refresh


Type A videotape

1 The VPR-1 had several problems, it did not record the vertical blanking interval, which is why it was not compliant to FCC broadcast standards. The video quality

was not as good as other broadcast VTRs. Thus Sony and Ampex agreed to make a SMPTE approved type Type C videotape|C format VTR (which was based on Type A). Hitachi also later made a C format VTR.


D-1 (Sony) - Format

1 Ancillary data can be put in H/V

blanking intervals


LaserDisc - Advantages

1 The vertical blanking interval, where the Macrovision signal would be

implemented, was also used for the internal timing on LaserDisc players, so test discs with Macrovision would

not play at all


Video - Analog television

1 An analog video format consists of more information than the visible content of the frame. Preceding and following the image

are lines and pixels containing synchronization information or a time

delay. This surrounding margin is known as a 'blanking interval' or 'blanking

region'; the horizontal and vertical front porch and back porch are the building

blocks of the blanking interval.https://store.theartofservice.com/the-blanking-interval-toolkit.html

Kinescope - Technology

1 The time taken physically to move the film on by one frame and stop it so that the gate can be opened to expose a new frame of film to the two field (video)|fields of television

picture is much longer than the vertical blanking interval between

these fields—so the film is still moving when the start of the next

field is being displayed on the television screenhttps://store.theartofservice.com/the-blanking-interval-toolkit.html

D-3 (video)

1 Four channels of 48 kHz 16-20 bit PCM audio, and other ancillary data,

are inserted during the vertical blanking interval


Dynamic random-access memory - Refresh rate

1 A few real-time systems refresh a portion of memory at a time

determined by an external timer function that governs the operation of the rest of a system, such as the

vertical blanking interval that occurs every 10–20ms in video equipment


NTSC - Lines and refresh rate

1 This blanking interval was originally designed to simply blank the

receiver's CRT to allow for the simple analog circuits and slow vertical

retrace of early TV receivers


Display Serial Interface

1 When in HS mode, commands are transmitted during the vertical blanking

interval.


Broadcast television systems - Viewing technology

1 For this reason, it is necessary to shut off the electron beam

(corresponding to a video signal of zero luminance) during the time it

takes to reorient the beam from the end of one line to the beginning of the next (horizontal retrace) and

from the bottom of the screen to the top (vertical retrace or vertical

blanking interval)https://store.theartofservice.com/the-blanking-interval-toolkit.html

Framebuffer - Page flipping

1 This switch is usually done during the vertical blanking interval to prevent

the screen from Screen tearing|tearing (i.e., half the old frame is shown, and half the new frame is

shown).


Teletext

1 Teletext is a means of sending text and diagrams to a properly equipped television screen by use of

one of the vertical blanking interval lines that together form the dark band dividing pictures

horizontally on the television screen.[http://news.google.com/newspapers?

nid=950dat=19790516id=DwEMAAAAIBAJsjid=21gDAAAAIBAJpg=6334,14832 Teletext: Soon You'll

Be Punching Buttons And Talking Back To Your TV] It offers a range of text-based information, typically including news, weather and TV

scheduleshttps://store.theartofservice.com/the-blanking-interval-toolkit.html

Teletext - Invention Design

1 His configuration contained all the fundamental elements of classic

Teletext including 24 text rows of 40 characters each, page selection,

multiple screens of information and vertical blanking interval data

transmission


Teletext - Technology

1 Teletext information is broadcast in the vertical blanking interval between image frames in a broadcast television signal


Teletext - Data transmission

1 Teletext in the PAL B system can make use the Vertical Blanking Interval|VBI lines 6–22 in first half

image and 318–334 in the other to transmit 360 data bits including clock run-in and framing code during the PAL#PAL signal details|active video period at a rate of using binary Non-return-to-zero|NRZ line

coding.[ http://www.ee-techs.com/tv/teletext-fullerton.pdf ee-techs.com – What is Teletext?],

2004ETS 300 706 – Enhanced Teletext specification, May 1997 The amplitude for a 0 is black level ±2% and a 1 is 66±6% of the difference between black

and peak white level


Teletext - Data transmission

1 In the case of the Ceefax and ORACLE systems and their successors in the UK, the teletext signal is transmitted as part of the ordinary analogue TV signal but concealed from view in the Vertical Blanking Interval (VBI) television lines which do not carry

picture information. The teletext signal is digitally coded as 45-byte packets, so the resulting rate is 7,175 bits per second per

used lines (41 7-bit 'bytes' per line, on each of 25 frames per second).


Teletext - Video Program System

1 Like teletext, this signal is also broadcast in the vertical blanking interval


Teletext - Digital teletext

1 This emulation is only possible due to the DVB-TXT and DVB-VBI sub-

standards of Digital Video Broadcasting|DVB, which allow a set-

top box or integrated DVB TV to reproduce the vertical blanking interval data in which Teletext is

carried.


576i

1 In analogue Vertical blanking interval|49 additional lines without

image content are added to the displayed frame of 576 lines to allow time for older CRT circuits to retrace

for the next frame,The 625-line television standard was introduced in

the early 1950s


Windows 98 - Windows Driver Model

1 TV listings could be updated from the Internet and WaveTop Data

Broadcasting allowed extra data about broadcasts to be received via regular television signals using an

antenna or cable, by embedding data streams into the vertical blanking interval (VBI) portion of existing

broadcast television signals.https://store.theartofservice.com/the-blanking-interval-toolkit.html

TBS (TV channel) - Other programming

1 Throughout the 1980s and the early 1990s, TBS also carried the Electra (teletext)|Electra teletext service on its vertical blanking interval; Electra was discontinued in 1993 due to a

lack of funding


Atari BASIC - Hardware support

1 A dedicated graphics microprocessor, ANTIC, reads these out during the

horizontal blanking interval to determine how to display the next TV

line


Atari BASIC - Interrupts

1 Short sections of machine language code can be executed during the

horizontal blanking interval, and this is typically done to change the values in the color registers,

horizontal sprite positions and so forth thus giving the appearance of more colors or more flexible sprites than the hardware provides ab initio


Atari BASIC - Interrupts

1 During the vertical blanking interval, a much longer interval, another interrupt is generated and the

Operating System hooks into this to perform some housekeeping tasks


NTSC - Lines and refresh rate

1 This blanking interval was originally designed to simply blank the

receiver's CRT to allow for the simple analog circuits and slow vertical

retrace of early TV receivers


Babylon 5 - Mastering problems

1 After visiting Warner Bros., who were stretching the Horizontal blanking interval|horizontal interval for an episode of Lois Clark: The New

Adventures of Superman|Lois Clark, producer John Copeland convinced them to allow Babylon 5 to be shot on Super 35|Super 35mm film stock


TBS (TV network) - Other programming

1 Throughout the 1980s and the early 1990s, TBS also carried the Electra (teletext)|Electra teletext service on its vertical blanking interval; Electra was discontinued in 1993 due to a

lack of funding


Closed captioning - Television and video

1 For all types of NTSC programming, captions are encoded into EIA-608|

line 21 of the vertical blanking interval – a part of the TV picture

that sits just above the visible portion and is usually unseen


Film frame - Video frames

1 Analog blanking intervals separated video frames in the same way that frame lines did

in film


Ricoh 5A22 - Major features

1 * Circuitry for generating Non-maskable interrupts on Vertical blanking interval|V-

blank


Ricoh 5A22 - Major features

1 ** Horizontal blanking interval|H-blank DMA, for transferring small

data sets at the end of each scanline outside of the active display period


Station identification - Television

1 Another way a television station can transmit its legal identification is to

do it continuously by putting readable text in the vertical blanking interval. One station that identifies this way is City (TV network)|City

owned-and-operated station CKVU-DT in Vancouver, British Columbia,

Canada.https://store.theartofservice.com/the-blanking-interval-toolkit.html

Rec. 601 - Signal format

1 The Rec. 601 signal can be regarded as if it is a digitally encoded analog component video signal, and thus the sampling includes data for the horizontal and vertical sync and

blanking intervals. Regardless of the frame rate, the luminance sampling frequency is 13.5MHz. The samples are uniformly Quantization (signal

processing)|quantized using 8 or 10 bit PCM codes in the YCbCr domain.https://store.theartofservice.com/the-blanking-interval-toolkit.html

625-line television system

1 In analogue Vertical blanking interval|49 additional lines without

image content are added to the displayed frame of 576 lines to allow

time for older cathode ray tube circuits to retrace for the next frame,The 625-line television

standard was introduced in the early 1950shttps://store.theartofservice.com/the-blanking-interval-toolkit.html

Coordinated Video Timings

1 The parameters defined by standard include horizontal blanking and

vertical blanking intervals, Horizontal scan rate|horizontal

frequency and refresh rate|vertical frequency (collectively, pixel clock

rate or video signal bandwidth), and horizontal sync|horizontal/vertical

sync polarity.https://store.theartofservice.com/the-blanking-interval-toolkit.html

Coordinated Video Timings - Reduced blanking

1 CVT also specifies a mode (CVT-R) which significantly reduces these

blanking intervals (to a period insufficient for CRT displays to work correctly) in the interests of saving

video signal bandwidth when modern displays such as LCD monitors are

being used, since such displays typically do not require these pauses

in the picture datahttps://store.theartofservice.com/the-blanking-interval-toolkit.html

Coordinated Video Timings - Reduced blanking

1 In revision 1.2, released in 2013, a new RB2 mode has been added which further reduces blanking interval and allows for unlimited vertical refresh rates, 4K/5K/8K

resolutions, 0.001 MHz pixel clock precision, and 1000/1001 modifier for ATSC/NTSC video timing modes.


NTSC - Vertical interval reference

1 The standard NTSC video image contains some lines (lines 1–21 of each field) that are

not visible (this is known as the Vertical Blanking Interval, or VBI); all are beyond the edge of the viewable image, but only lines 1–

9 are used for the vertical-sync and equalizing pulses. The remaining lines were

deliberately blanked in the original NTSC specification to provide time for the electron beam in CRT-based screens to return to the

top of the display.https://store.theartofservice.com/the-blanking-interval-toolkit.html

NTSC - Vertical interval reference

1 Early teletext applications also used vertical blanking interval lines 14–18 and 20, but teletext over NTSC was never widely adopted by viewers.

[http://experimentaltvcenter.org/history/tools/ttext.php3?id=16 Tools | The

History Project]


Display controller

1 In any case, it's the VDC's responsibility to generate the timing of the necessary video signals, such

as the horizontal and vertical Component video sync|

synchronisation signals, and the Video formats|blanking interval

signal.


Videotex - North America

1 Telidon was able to deliver service using the vertical blanking interval of

a TV signal or completely by telephone using a Bell 202 modem|

Bell 202 style (split baud rate 150/1200) modem


Nagravision - Analog system

1 A smartcard security microcontroller (in a key-shaped package) decrypts data that is transmitted during the blanking intervals of the TV signal

and extracts the random seed value needed for controlling the random

number generation


SMPTE timecode - SMPTE timecode media

1 #Vertical interval timecode, a.k.a. 'VITC' (pronounced vit-see): recorded

directly into the VBI (vertical blanking interval) of the video signal

on each frame of video. The advantage of VITC is that, since it is a part of the playback video, it can be

read when the tape is stationary.


Raster scan - Scanning pattern

1 In fact, spikes do occur, both horizontally and vertically, and the corresponding horizontal blanking

interval and vertical blanking interval give the deflection currents settle time to retrace and settle to their

new value. This happens during the blanking interval.


Automatic gain control - Audio/video

1 Most VCR circuits use the amplitude of the vertical blanking interval|

vertical blanking pulse to operate the AGC. Video copy control schemes such as Macrovision exploit this,

inserting spikes in the pulse which will be ignored by most television

sets, but cause a VCR's AGC to overcorrect and corrupt the

recording.https://store.theartofservice.com/the-blanking-interval-toolkit.html

Genlock - Natlock and Icelock

1 Natlock is a picture source synchronizing system using audio tone signals to describe the timing discrepancies between composite video signals, whilst Icelock uses

digital information conveyed in the vertical blanking interval of a

composite video signal.


Ghost-canceling reference

1 In the United States, the GCR signal is a chirp in frequency of the modulating signal from 0

Hz to 4.2 MHz, transmitted during the vertical blanking interval over one video line, shifted in phase by 180° once per frame, with this pattern inverted every four lines. Television

receivers generate their own local versions of this signal, and use the comparison between the local and remote signals to tune out any

ghost images on the screen.


Extended Data Services

1 XDS uses the same line in the vertical blanking interval as closed

captioning (NTSC line 21), and shares the available second field (video)|

video field bandwidth with the closed captioning channels CC3 and CC4,

and with the text channels TXT3 and TXT4.


Vertical blanking interval

1 The 'vertical blanking interval' ('VBI'), also known as the 'vertical interval' or 'VBLANK', is the time difference

between the last line of one frame or field of a raster graphics|raster

display, and the beginning of the first line of the next frame



1 Modern CRT circuitry does not require such a long blanking interval, and

thin panel displays require none, but the standards were established when the delay was needed (and to allow

the continued use of older equipment)



1 In analog television systems the vertical blanking interval can be used for datacasting (to carry digital data), since nothing sent during the VBI is

displayed on the screen; various test signals, vertical interval timecode|

time codes, closed captioning, teletext, CGMS-A copy-protection

indicators, and various data encoded by the Extended Data Services|XDS

protocol (e.g., the content ratings for V-chip use) and other digital data can

be sent during this time period



1 In video game systems the vertical blanking pulses are extensively used to time the

plotting of new graphics/removal of old ones in order to avoid screen tearing, as they

occur at an accurately known frequency, and many systems up to the History of video

game consoles (fourth generation)|16-bit era featured games and other graphical

programs where drawing was conducted during the blanking interval for this reason


Television encryption - Leitch Technology

1 There was also a version that encrypted the audio using a digital

audio stream in the horizontal blanking interval like the VCII

system. One US network used that for its affiliate feeds and would turn off the analog sub carriers on the

satellite feed.


Television encryption - Nagravision analogue system

1 A smartcard security microcontroller (in a key-shaped package) decrypts data that is transmitted during the blanking intervals of the TV signal

and extracts the random seed value needed for controlling the random

number generation


CGMS-A

1 'Copy Generation Management System - Analog' ('CGMS-A') is a copy

protection mechanism for analog signal|analog television signals. It

consists of a waveform inserted into the non-picture Vertical Blanking

Interval (VBI) of an analogue video signal. If a compatible recording

device (for example, a DVD recorder) detects this waveform, it may block

or restrict recording of the video content.


VIT signals - Blanking in CVS

1 In a composite video signal (CVS) there are two types of blanking: Horizontal blanking interval|horizontal and Vertical blanking interval|vertical. Horizontal blanking is between lines and vertical blanking is

between fields (half frames). In a poorly tuned TV receiver the horizontal blanking can be

seen at the right or left of the image and the vertical blanking can be seen at the top or

bottom of the image. VIT signals are inserted in the vertical blanking.


Video Encoded Invisible Light - Other uses

1 VEIL acts together with CGMS-A signal (broadcast flag) in the vertical blanking

interval, where it is used to encode the Rights Assertion Mark (RAM) signal. The CGMS-A can be stripped too easily from the analog signal, therefore the presence of RAM but absence of CGMS-A will tell the copy protection system to

deny the copy.http://www.extremedrm.com/article/How+Will+Veils+Technology+Plug+The+Analog+

Hole/164259_1.aspxhttps://store.theartofservice.com/the-blanking-interval-toolkit.html

Analog TV - Structure of a video signal

1 The front porch is a brief (about 1.5 microsecond) period inserted between the end of each transmitted line of picture and

the leading edge of the next line sync pulse. Its purpose was to allow voltage levels to stabilise in older televisions, preventing

interference between picture lines. The front porch is the first component of the horizontal

blanking interval which also contains the horizontal sync pulse and the back porch.


Multiple buffering - Page flipping

1 The page-flip is much faster than copying the data and can guarantee that tearing will not be seen as long

as the pages are switched over during the monitor's vertical blanking

interval—the blank period when no video data is being drawn. The

currently active and visible buffer is called the 'front buffer', while the

background page is called the back buffer.https://store.theartofservice.com/the-blanking-interval-toolkit.html

Horizontal scan rate

1 CRT timings actually include some horizontal scans before the visible display, after it, and

during the travel from bottom to top (known as vertical back porch, vertical front porch, and

vertical sync width, respectively, and collectively known as Vertical blanking interval|vertical blank

time), so the horizontal scan rate does not directly correlate to visible display lines, unless the

unseen lines are also known, but it can still be used to approximate the display lines, as the total

blank time is usually a small but significant portion of the total lines.


Horizontal scan rate - Example

1 *Taking Vertical blanking interval into account, it would actually draw

1024x1.05 lines for a full frame cycle


Guide Plus - Technical overview

1 The original analog television|analog service uses the vertical blanking interval (VBI) of :wikt:host|host

television stations that datacast the service, similar to the manner that closed captioning and teletext are

broadcast


Overscan - Datacasting

1 The simplest form of this is closed captioning and teletext, both sent in the vertical blanking interval (VBI)


Overscan - 625 / 525 or 576 / 480

1 A portion of this interval available in analogue, known as the vertical

blanking interval, can be used for older forms of analogue datacasting such as Teletext services (like Ceefax

and subtitling in the UK). The equivalent service on Digital

television does not use this method and instead often uses MHEG-5|

MHEG.https://store.theartofservice.com/the-blanking-interval-toolkit.html

Atari 8-bit - Software-driven modes

1 It was also possible by using the Display List Interrupt facility to display far more than the usual number of sprites on the screen

during the vertical blanking interval, with more colours than available


Nominal analogue blanking

1 It consists of a variable and arbitrary gap of black (or nearly black) pixels at the left and right sides, which correspond to the end and start of the horizontal blanking interval: the

Analog television#Structure of a video signal|front porch at the right side (the end of a line,

before the sync pulse), and the Analog television#Structure of a video signal|back

porch at the left side (the start of a line, after the sync pulse and before drawing the next

line)https://store.theartofservice.com/the-blanking-interval-toolkit.html

Horizontal blanking interval

1 'Horizontal blanking interval' refers to a part of the process of displaying images on a computer monitor or

television display device|screen via raster scanning


Horizontal blanking interval - HBlank effects

1 The Super Nintendo Entertainment System|Super NES's Mode 7 used the horizontal blanking interval to vary

the scaling and rotation of one background layer on a scanline by

scanline basis to create many different effects


Local on the 8s - History

1 Weather information is received from the vertical blanking interval of the

TWC video feed and from data transmitted via satellite, which is

then inserted over the TWC feed with local insertion technologies


ORACLE (teletext) - History

1 Under the original plans for the ITV franchise renewal, they were to have

been scrapped at the end of 1992 and the few Vertical blanking

interval|scan lines they used given to the highest bidder


CRT TV - Display technology

1 It actually could be slightly higher than that, but the vertical blanking

interval (VBI), allows time for magnetic beam scanning retrace in affordable CRT-equipped television

receivers


Vertical interval timecode

1 'Vertical Interval Timecode' ('VITC', pronounced vitsee or vits) is a form of SMPTE timecode embedded as a

pair of black-and-white bars in a video signal. These lines are

typically inserted into the vertical blanking interval of the video signal.

There can be more than one VITC pair in a single frame of video: this can be used to encode extra data

that will not fit in a standard timecode frame.


For More Information, Visit:

• https://store.theartofservice.com/the-blanking-interval-toolkit.html

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