But the frame is 525 lines. That leaves 45 lines. Does anyone know what
each one of them does? I mean specifically. Like, line x is the time of
day, etc.

Thanks,

On Tue, 30 Aug 2005 15:19:28 -0700, in rec.audio.pro
wrote:

But the frame is 525 lines. That leaves 45 lines. Does anyone know what
each one of them does? I mean specifically. Like, line x is the time of
day, etc.

Thanks,

there area few lines that where originally used as a safegap and
setting up for the next frame, its quite techinical and boring, now
used for teletext and other data.

Dont worry about it, worry about the programmes more


martin

wrote:

But the frame is 525 lines. That leaves 45 lines. Does anyone know what
each one of them does? I mean specifically. Like, line x is the time of
day, etc.

It's 625 lines in PAL of course which is in wider use worldwide than NTSC.

The 'spare lines' are used in the UK to carry teletext data and Nicam digital
sound.

Graham

martin griffith wrote:

On Tue, 30 Aug 2005 15:19:28 -0700, in rec.audio.pro
wrote:

But the frame is 525 lines. That leaves 45 lines. Does anyone know what
each one of them does? I mean specifically. Like, line x is the time of
day, etc.

Thanks,

there area few lines that where originally used as a safegap and
setting up for the next frame, its quite techinical and boring, now
used for teletext and other data.

Dont worry about it, worry about the programmes more

Actually, the 'spares lines' were needed for vertical retrace time.

Graham

In article ,
wrote:
But the frame is 525 lines. That leaves 45 lines. Does anyone know what
each one of them does? I mean specifically. Like, line x is the time of
day, etc.

The other 45 lines are the vertical blanking interval. Originally, in 1939,
they were all just deep black, blacker than black, in order to give the receiver
a synchronization signal to start a new field. There had to be a lot
of them because it took a long time to sweep the electron beam up to the
top of the screen on early tubes.

In the eighties they started putting all kinds of information in the
VBI, in order to send teletext, to transmit time of day, and to store
video timecode. It was basically wasted information, so why not put
something there?

But, they are still there, and a TV set made in 1939 can still synch up
properly to a broadcast today.

Tektronix used to have a really neat handout about the various data
formats for the VBI, which is probably on the web somewhere.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."

martin griffith wrote:

there area few lines that where originally used as a safegap and
setting up for the next frame, its quite techinical and boring, now
used for teletext and other data.

Dont worry about it, worry about the programmes more

The programs are all stupid. My TV has a "brightness" control, but no
matter how far I turn it, the programming remains stupid.
--scott

In the supermarket, the survey woman asked what my favorite TV show was
and I told her it was _Bars and Tone_. I like it much more than that
old TV show with the Indian that used to have the late night timeslot.
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

LOL!!
DaveT

In the eighties they started putting all kinds of information in the
VBI, in order to send teletext, to transmit time of day, and to store
video timecode. It was basically wasted information, so why not put
something there?

But, they are still there, and a TV set made in 1939 can still synch up
properly to a broadcast today.

Tektronix used to have a really neat handout about the various data
formats for the VBI, which is probably on the web somewhere.

Last I checked, some stations put color bars on one line, multiburst on
another, and some other patters on other lines. These are useless for
display, but perfect for checking signal performance with vectorscopes and
waveform monitors. Otherwise, those lines are wasted space.

-John O

JohnO wrote:

Last I checked, some stations put color bars on one line, multiburst on
another, and some other patters on other lines. These are useless for
display, but perfect for checking signal performance with vectorscopes and
waveform monitors. Otherwise, those lines are wasted space.

It's called VITS, Vertical Interval Test Signals

From the Grass Valley Dictionary:

VITS - A signal that may be included during the vertical blanking
interval to permit on-the-air testing of video circuit functions
and adjustments.

Other data that may be encoded in the vertical interval are closed captioning,
VIRS, Vertical Interval Reference Signals, and VITC, Vertical Interval TimeCode,
which is encoded SMPTE timecode data.

--
================================================== ======================
Michael Kesti | "And like, one and one don't make
| two, one and one make one."
mrkesti at comcast dot net | - The Who, Bargain

In article ,
(Scott Dorsey) wrote:

martin griffith wrote:

there area few lines that where originally used as a safegap and
setting up for the next frame, its quite techinical and boring, now
used for teletext and other data.

Dont worry about it, worry about the programmes more

The programs are all stupid. My TV has a "brightness" control, but no
matter how far I turn it, the programming remains stupid.
--scott

In the supermarket, the survey woman asked what my favorite TV show was
and I told her it was _Bars and Tone_. I like it much more than that
old TV show with the Indian that used to have the late night timeslot.

Cheech: "Hey man, what'cha doin'?"
Chong: "Hey, I'm watching a movie about Indians, but it's real boring."
Cheech: "Hey man, that's no movie, that's a test pattern!"

normanstrong wrote ...
But the frame is 525 lines. That leaves 45 lines. Does
anyone know what each one of them does? I mean
specifically. Like, line x is the time of day, etc.

Most of them are not assigned to particular functions. Back
when RS-170 television was invented, the vertical interval
was required to allow the CRT beam to return to the other
end of the screen. Sometimes you can see diagonal lines
across the screen where the vertical interval is not blanked
completely.

Nowdays, they are used for vertical-interval timecode: VITC,
vertical-interval test signals: VITS (sometimes you can see
a single line of color bars, multi-burst, etc.), closed-caption
data (quite commonly seen as white dashes on line 21 changing
rapidly during dialog, etc.)

In the PAL territories, the vertical-interval is also used for
Teletext, etc.

Google for vertical-interval signals and you'll find more than
you wanted to know.