Apologies, it seems there is already a thread, started on the 1st Oct.
--
Graham.
%Profound_observation%
Yes but what is the point of any dog or q or anything else, surely these days if you want to watermark your programs, it could be done digitally without making any use of the picture area at all.
Exactly. The cue dot is not something that the viewer needs to be aware of, so it is odd that it was*ever* placed in the picture lines, even going back to analogue days.
"Brian Gaff (Sofa)" <briang1@blueyonder.co.uk> wrote in message news:sjrpbb$r3k$1@dont-email.me...
Yes but what is the point of any dog or q or anything else, surely
these days if you want to watermark your programs, it could be done digitally without making any use of the picture area at all.
Exactly. The cue dot is not something that the viewer needs to be aware
of, so it is odd that it was *ever* placed in the picture lines, even
going back to analogue days. You'd think that they could have used one
of the invisible "teletext lines" for cueing information.
On 09/10/2021 13:19, NY wrote:
Exactly. The cue dot is not something that the viewer needs to be aware
of, so it is odd that it was*ever* placed in the picture lines, even
going back to analogue days.
Was it ever used as a cue to a remote OB where they might to have used a standard TV receiver?
One near here, was not even able to receive BBC2 (analogue) so fed BBC2
off air sound to the OB so they could be cued in.
Might be no longer necessary but I know that BBC OBs were great
believers in "belt and braces" with a bit of string in case they both
fail and it does not cost anything.
In article <sjs1d2$fl3$1@dont-email.me>, NY <me@privacy.invalid> wrote:
"Brian Gaff (Sofa)" <briang1@blueyonder.co.uk> wrote in messageThe cue dot was invented well before teletext was even a dream in
news:sjrpbb$r3k$1@dont-email.me...
Yes but what is the point of any dog or q or anything else, surelyExactly. The cue dot is not something that the viewer needs to be aware
these days if you want to watermark your programs, it could be done
digitally without making any use of the picture area at all.
of, so it is odd that it was *ever* placed in the picture lines, even
going back to analogue days. You'd think that they could have used one
of the invisible "teletext lines" for cueing information.
somebody's eye.
On 09/10/2021 13:47, charles wrote:
In article <sjs1d2$fl3$1@dont-email.me>, NY <me@privacy.invalid> wrote:The cue dot was invented by the movie industry, to signal when a reel
"Brian Gaff (Sofa)" <briang1@blueyonder.co.uk> wrote in messageThe cue dot was invented well before teletext was even a dream in
news:sjrpbb$r3k$1@dont-email.me...
Yes but what is the point of any dog or q or anything else, surelyExactly. The cue dot is not something that the viewer needs to be aware
these days if you want to watermark your programs, it could be done
digitally without making any use of the picture area at all.
of, so it is odd that it was *ever* placed in the picture lines, even
going back to analogue days. You'd think that they could have used one
of the invisible "teletext lines" for cueing information.
somebody's eye.
was coming to an end, (for the benefit of the cinema projectionist)
Mark Carver <mark.carver@invalid.invalid> wrote:
On 09/10/2021 13:47, charles wrote:Any idea why the disaster recovery centre needs to have this cue dot? I’m curious as to what purpose it might serve.
In article <sjs1d2$fl3$1@dont-email.me>, NY <me@privacy.invalid> wrote: >>>> "Brian Gaff (Sofa)" <briang1@blueyonder.co.uk> wrote in messageThe cue dot was invented by the movie industry, to signal when a reel
news:sjrpbb$r3k$1@dont-email.me...The cue dot was invented well before teletext was even a dream in
Yes but what is the point of any dog or q or anything else, surelyExactly. The cue dot is not something that the viewer needs to be aware >>>> of, so it is odd that it was *ever* placed in the picture lines, even
these days if you want to watermark your programs, it could be done
digitally without making any use of the picture area at all.
going back to analogue days. You'd think that they could have used one >>>> of the invisible "teletext lines" for cueing information.
somebody's eye.
was coming to an end, (for the benefit of the cinema projectionist)
"charles" <charles@candehope.me.uk> wrote in message news:5978b56f94charles@candehope.me.uk...
In article <sjs1d2$fl3$1@dont-email.me>, NY <me@privacy.invalid> wrote:
"Brian Gaff (Sofa)" <briang1@blueyonder.co.uk> wrote in message
news:sjrpbb$r3k$1@dont-email.me...
Yes but what is the point of any dog or q or anything else, surely
these days if you want to watermark your programs, it could be done
digitally without making any use of the picture area at all.
Exactly. The cue dot is not something that the viewer needs to be
aware of, so it is odd that it was *ever* placed in the picture lines,
even going back to analogue days. You'd think that they could have
used one of the invisible "teletext lines" for cueing information.
The cue dot was invented well before teletext was even a dream in somebody's eye.
Yes, but you'd think that once teletext (or sound-in-sync) had been
invented, they'd use a more professional and public-invisible way of
cueing an OB than putting a rolling square or a double-quote mark on the screen.
In article <sjs1d2$fl3$1@dont-email.me>, NY <me@privacy.invalid> wrote:
"Brian Gaff (Sofa)" <briang1@blueyonder.co.uk> wrote in message
news:sjrpbb$r3k$1@dont-email.me...
Yes but what is the point of any dog or q or anything else, surely
these days if you want to watermark your programs, it could be done
digitally without making any use of the picture area at all.
Exactly. The cue dot is not something that the viewer needs to be aware
of, so it is odd that it was *ever* placed in the picture lines, even
going back to analogue days. You'd think that they could have used one
of the invisible "teletext lines" for cueing information.
The cue dot was invented well before teletext was even a dream in
somebody's eye.
this week Waltham has been getting the wrong feeds or no feeds for C4
and its siblings.
On 09/10/2021 20:06, Mark Carver wrote:
this week Waltham has been getting the wrong feeds or no feeds for C4
and its siblings.
I didn't know that.
Bill
Exactly. The cue dot is not something that the viewer needs to be aware of, >so it is odd that it was *ever* placed in the picture lines, even going back >to analogue days. You'd think that they could have used one of the invisible >"teletext lines" for cueing information. OK, so you need a way of one end of >a live link setting that information and the other end reading it, and I >suppose it means that *any* monitor, including an off-air one, can see it, >but it is a very clumsy blunt instrument to solve a specific problem.
williamwright <wrightsaerials@f2s.com> wrote:
On 09/10/2021 20:06, Mark Carver wrote:Is there something unusual/non-standard about Waltham’s feed arrangements that might have caused this, in addition to the ongoing use of the disaster recovery suite?
this week Waltham has been getting the wrong feeds or no feeds for C4I didn't know that.
and its siblings.
Bill
"Brian Gaff (Sofa)" <briang1@blueyonder.co.uk> wrote in message news:sjrpbb$r3k$1@dont-email.me...
Yes but what is the point of any dog or q or anything else, surely these
days if you want to watermark your programs, it could be done digitally
without making any use of the picture area at all.
Exactly. The cue dot is not something that the viewer needs to be aware
of, so it is odd that it was *ever* placed in the picture lines, even
going back to analogue days. You'd think that they could have used one of
the invisible "teletext lines" for cueing information. OK, so you need a
way of one end of a live link setting that information and the other end reading it, and I suppose it means that *any* monitor, including an
off-air one, can see it, but it is a very clumsy blunt instrument to solve
a specific problem.
A DOG is different: it is designed to watermark the visible picture (to prevent other people "stealing" it and using it without permission) and it serves to advertise the "brandname" of the channel. But the fact that it
is turned off during adverts shows contempt for the viewer, if they are prepared to turn it off to keep the advertisers happy but not to keep the viewers happy. If I "ruled the world" (!) I'd make it law that all adverts
in all forms (print, TV etc) had to have a huge "ADVERT" DOG ("DOGshit" ?) splattered all over the middle to make it abundantly clear that this is
*not* programme material. Adverts are a necessary evil - emphasis on that word "evil" - which pays the bills, and they should not be given any concessions that are not given to programmes. I really *hate* being
forcibly advertised at (rant over!)
I wonder why the current triangle symbol at the top right of C5 was placed there. It's not advertising the C5 brand (there is a "5" DOG at the top
left for that) so its only purpose is to let engineers know that the programme is coming from the disaster recovery server - and you'd think
that an invisible embedded flag could be used for that since the public do not need to know it. Again, a very crude blunt-instrument solution.
In article <sjs2ur$pmn$1@dont-email.me>, MB <MB@nospam.net> wrote:
On 09/10/2021 13:19, NY wrote:
Exactly. The cue dot is not something that the viewer needs to be aware
of, so it is odd that it was*ever* placed in the picture lines, even
going back to analogue days.
Was it ever used as a cue to a remote OB where they might to have used a
standard TV receiver?
Yes.
One near here, was not even able to receive BBC2 (analogue) so fed BBC2
off air sound to the OB so they could be cued in.
Might be no longer necessary but I know that BBC OBs were great
believers in "belt and braces" with a bit of string in case they both
fail and it does not cost anything.
--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle
In article <sjs1d2$fl3$1@dont-email.me>, NY <me@privacy.invalid> wrote:
"Brian Gaff (Sofa)" <briang1@blueyonder.co.uk> wrote in message
news:sjrpbb$r3k$1@dont-email.me...
Yes but what is the point of any dog or q or anything else, surely
these days if you want to watermark your programs, it could be done
digitally without making any use of the picture area at all.
Exactly. The cue dot is not something that the viewer needs to be aware
of, so it is odd that it was *ever* placed in the picture lines, even
going back to analogue days. You'd think that they could have used one
of the invisible "teletext lines" for cueing information.
The cue dot was invented well before teletext was even a dream in
somebody's eye.
--
from KT24 in Surrey, England
"I'd rather die of exhaustion than die of boredom" Thomas Carlyle
On 09/10/2021 13:47, charles wrote:
In article <sjs1d2$fl3$1@dont-email.me>, NY <me@privacy.invalid> wrote:The cue dot was invented by the movie industry, to signal when a reel was coming to an end, (for the benefit of the cinema projectionist)
"Brian Gaff (Sofa)" <briang1@blueyonder.co.uk> wrote in messageThe cue dot was invented well before teletext was even a dream in
news:sjrpbb$r3k$1@dont-email.me...
Yes but what is the point of any dog or q or anything else, surelyExactly. The cue dot is not something that the viewer needs to be aware
these days if you want to watermark your programs, it could be done
digitally without making any use of the picture area at all.
of, so it is odd that it was *ever* placed in the picture lines, even
going back to analogue days. You'd think that they could have used one
of the invisible "teletext lines" for cueing information.
somebody's eye.
On 10/10/2021 06:28, Tweed wrote:
williamwright <wrightsaerials@f2s.com> wrote:
On 09/10/2021 20:06, Mark Carver wrote:Is there something unusual/non-standard about Waltham‘s feed arrangements that might have caused this, in addition to the ongoing use of the disaster recovery suite?
this week Waltham has been getting the wrong feeds or no feeds for C4I didn't know that.
and its siblings.
Bill
No, it's all within Arqiva's area of responsibility to sort out, not Red
Bee or C4 themselves.
On the night of the 'fire', Arqiva got in a muddle and managed to route
E4+1 to S4C's Welsh transmitters (probably because S4C use E4+1'S normal 'slot' in Wales)
There was nothing physically at Waltham that was wrong, it'll have
probably been at Arqiva's 'Central/Northern England' CCM where things
were misconfigured.
Secret location, but you don't need to be Sherlock Holmes to guess where
it might be.
By the way, the Wales coding region is called 'Wenvoe', and there were briefly problems with Winter Hill's feeds too. Maybe it's a 'W' thing.
It is at the end of the alphabet !!
On 09/10/2021 15:59, Tweed wrote:
Mark Carver <mark.carver@invalid.invalid> wrote:It's to let the platform operators downstream know (Arqiva, Sky, Virgin
On 09/10/2021 13:47, charles wrote:Any idea why the disaster recovery centre needs to have this cue dot? I'm
In article <sjs1d2$fl3$1@dont-email.me>, NY <me@privacy.invalid> wrote: >>>>> "Brian Gaff (Sofa)" <briang1@blueyonder.co.uk> wrote in messageThe cue dot was invented by the movie industry, to signal when a reel
news:sjrpbb$r3k$1@dont-email.me...The cue dot was invented well before teletext was even a dream in
Yes but what is the point of any dog or q or anything else, surely >>>>>> these days if you want to watermark your programs, it could be done >>>>>> digitally without making any use of the picture area at all.Exactly. The cue dot is not something that the viewer needs to be
aware
of, so it is odd that it was *ever* placed in the picture lines, even >>>>> going back to analogue days. You'd think that they could have used one >>>>> of the invisible "teletext lines" for cueing information.
somebody's eye.
was coming to an end, (for the benefit of the cinema projectionist)
curious as to what purpose it might serve.
etc) that's the feed they are getting, rather than the primary one.
You may think that's a bit OTT, but as it is Arqiva got themselves in a
bit of muddle when 'the event' happened two weeks ago, and ended up
feeding E4+1 to S4C's DTT transmitters, and still even this week Waltham
has been getting the wrong feeds or no feeds for C4 and its siblings.
It's not for public consumption (no cue dot is), and really could do with being well outside of the 'safe area'
williamwright <wrightsaerials@f2s.com> wrote:
On 09/10/2021 20:06, Mark Carver wrote:
this week Waltham has been getting the wrong feeds or no feeds for C4
and its siblings.
I didn't know that.
Bill
Is there something unusual/non-standard about Waltham's feed arrangements that might have caused this, in addition to the ongoing use of the
disaster
recovery suite?
That does not mean that it had to be in the picture though. There were
always spare lines and if they use broadcast kit then its relatively easy to adjust the set to see those lines or have a circuit to respond to them.
It does not sound like the whole signalling system has been thought through >at all then.
Again though, it need not be in the picture area, there are parts of a film which are black and a simple sensor behind a secondary gate hole would have sufficed.
On 10/10/2021 10:42, Brian Gaff (Sofa) wrote:
That does not mean that it had to be in the picture though. There were always spare lines and if they use broadcast kit then its relatively
easy to adjust the set to see those lines or have a circuit to respond
to them.
Yes, but the problem is you couldn't be sure that anything in the
vertical blanking interval would get 'muted' during the flyback period.
That was one of the big concerns about introducing teletext, and it also
held back the number of VBI lines used for some years. Initially only 2
were used I think ?
On Sat, 9 Oct 2021 13:19:44 +0100, "NY" <me@privacy.invalid> wrote:
Exactly. The cue dot is not something that the viewer needs to be aware of, >> so it is odd that it was *ever* placed in the picture lines, even going back >> to analogue days. You'd think that they could have used one of the invisible >> "teletext lines" for cueing information. OK, so you need a way of one end of >> a live link setting that information and the other end reading it, and I
suppose it means that *any* monitor, including an off-air one, can see it, >> but it is a very clumsy blunt instrument to solve a specific problem.
Some equipment reinserts new sync and blanking, so anything outside
the visible picture lines wouldn't survive that. Depending on where
you intended to make use of cue dots, this might present a problem.
I don't know the history of TV cue dots, but I suspect they were first implemented in the days of CRTs that were either round or had
extremely rounded corners, when it was common practice to overscan the
image on a domestic TV set to fill every part of the screen.
On Sun, 10 Oct 2021 10:37:40 +0100, "Brian Gaff \(Sofa\)" <briang1@blueyonder.co.uk> wrote:
It does not sound like the whole signalling system has been thought
through
at all then.
Indeed. I think evolution has played as much of a part as planning. In
the broadcast environment, opportunities to scrap entire systems and
design again from scratch are few and far between, so it's more usual
to adapt or augment what's already there. Occasionally things that in
the biological world would be called "atavisms" are left over from
this process, even if they no longer have a purpose.
For example, the RG board in the Sony chip cameras that I used to look
after. The initials on the circuit boards in Sony cameras would
usually reflect their purpose, VA for video preamplifier, PR for
processing amplifier, EN for encoder, DF for deflection and so on. The
RG board was for registration; it was the little circuit board that
enabled superimposition of the inverted green signal on either of the
other two to assist registration of the three images. All their tube
cameras had this, but here it still was like an evolutionary leftover
in a chip camera where there was nothing to do with registration that
you could adjust. Perhaps nobody had told the designers to stop.
"Roderick Stewart" <rjfs@escapetime.myzen.co.uk> wrote in message news:0ue5mg1ogal4g58ccd0ggjrde7149qptmn@4ax.com...
On Sun, 10 Oct 2021 10:37:40 +0100, "Brian Gaff \(Sofa\)"
<briang1@blueyonder.co.uk> wrote:
It does not sound like the whole signalling system has been thought
through
at all then.
Indeed. I think evolution has played as much of a part as planning. In
the broadcast environment, opportunities to scrap entire systems and
design again from scratch are few and far between, so it's more usual
to adapt or augment what's already there. Occasionally things that in
the biological world would be called "atavisms" are left over from
this process, even if they no longer have a purpose.
For example, the RG board in the Sony chip cameras that I used to look
after. The initials on the circuit boards in Sony cameras would
usually reflect their purpose, VA for video preamplifier, PR for
processing amplifier, EN for encoder, DF for deflection and so on. The
RG board was for registration; it was the little circuit board that
enabled superimposition of the inverted green signal on either of the
other two to assist registration of the three images. All their tube
cameras had this, but here it still was like an evolutionary leftover
in a chip camera where there was nothing to do with registration that
you could adjust. Perhaps nobody had told the designers to stop.
I've seen the same analogue legacy in some TV programmes. The first and last lines are sometimes half black and half picture, as you'd get in the days of 575 (272.5) lines per frame (or field). And that's not just old analogue programmes from the archive. This is modern programmes which have presumably been shot, edited and transmitted all in the digital domain.
NY <me@privacy.invalid> wrote:
"Roderick Stewart" <rjfs@escapetime.myzen.co.uk> wrote in message
news:0ue5mg1ogal4g58ccd0ggjrde7149qptmn@4ax.com...
On Sun, 10 Oct 2021 10:37:40 +0100, "Brian Gaff \(Sofa\)"
<briang1@blueyonder.co.uk> wrote:
It does not sound like the whole signalling system has been thought
through
at all then.
Indeed. I think evolution has played as much of a part as planning. In
the broadcast environment, opportunities to scrap entire systems and
design again from scratch are few and far between, so it's more usual
to adapt or augment what's already there. Occasionally things that in
the biological world would be called "atavisms" are left over from
this process, even if they no longer have a purpose.
For example, the RG board in the Sony chip cameras that I used to look
after. The initials on the circuit boards in Sony cameras would
usually reflect their purpose, VA for video preamplifier, PR for
processing amplifier, EN for encoder, DF for deflection and so on. The
RG board was for registration; it was the little circuit board that
enabled superimposition of the inverted green signal on either of the
other two to assist registration of the three images. All their tube
cameras had this, but here it still was like an evolutionary leftover
in a chip camera where there was nothing to do with registration that
you could adjust. Perhaps nobody had told the designers to stop.
I've seen the same analogue legacy in some TV programmes. The first and
last
lines are sometimes half black and half picture, as you'd get in the days
of
575 (272.5) lines per frame (or field). And that's not just old analogue
programmes from the archive. This is modern programmes which have
presumably
been shot, edited and transmitted all in the digital domain.
The BBC programme submission guidelines that Mark Carver linked to earlier specifically outlaw these half lines from being visible.
"Tweed" <usenet.tweed@gmail.com> wrote in message >news:sjuoh9$ct3$1@dont-email.me...[]
NY <me@privacy.invalid> wrote:
I've seen the same analogue legacy in some TV programmes. The first
and last
lines are sometimes half black and half picture, as you'd get in the >>>days of
575 (272.5) lines per frame (or field). And that's not just old analogue >>> programmes from the archive. This is modern programmes which have >>>presumably
been shot, edited and transmitted all in the digital domain.
The BBC programme submission guidelines that Mark Carver linked to earlier >> specifically outlaw these half lines from being visible.
Is that for archive programmes, where the half lines will always be
present and are presumably blanked to comply with the guidelines, or is
it also for new programmes on non-analogue equipment? I've seen it on
(live) breakfast TV programmes and regional news programmes, especially
BBC.
On 10/10/2021 10:45, Brian Gaff (Sofa) wrote:
Again though, it need not be in the picture area, there are parts of a film >> which are black and a simple sensor behind a secondary gate hole would have >> sufficed.
"Simple sensor"? Light, photoelectric cell, valve amplifier, relay, lamp >where the projectionist can see it? You'll be saying that the second >projector starting and the switchover is done automatically next!
Then the projectionist will go to sleep and not notice that the new reel
is from a completely different film!
I've wondered before now if any digital equipment - either the sensors
(CCD or whatever) in cameras or the displays in monitors/TVs - were
rotated a very tiny amount to take account of the fact that, if
following the original standard completely, scan lines were not totally >horizontal (the end of the line being 1/575 of the image height lower
than the start). I'm pretty sure that the answer is no in both cases,
but the fact therefore remains that, for archive material from analogue
days at least, the picture we now see is both rotated and distorted,
though by a totally imperceptible amount.
On 10/10/2021 10:45, Brian Gaff (Sofa) wrote:
Again though, it need not be in the picture area, there are parts of a
film which are black and a simple sensor behind a secondary gate hole would have sufficed.
"Simple sensor"? Light, photoelectric cell, valve amplifier, relay, lamp where the projectionist can see it? You'll be saying that the second projector starting and the switchover is done automatically next!
Then the projectionist will go to sleep and not notice that the new reel
is from a completely different film!
On Sun, 10 Oct 2021 16:26:40 +0100, "J. P. Gilliver (John)" ><G6JPG@255soft.uk> wrote:
I've wondered before now if any digital equipment - either the sensors
(CCD or whatever) in cameras or the displays in monitors/TVs - were
rotated a very tiny amount to take account of the fact that, if
following the original standard completely, scan lines were not totally >>horizontal (the end of the line being 1/575 of the image height lower
than the start). I'm pretty sure that the answer is no in both cases,
but the fact therefore remains that, for archive material from analogue >>days at least, the picture we now see is both rotated and distorted,
though by a totally imperceptible amount.
Yes, an analogue raster is technically not a perfect rectangle, but a >trapezium with a downward slope of 2/625 towards the right.
However, it was common practice to use the horizontal scanning lines
as a reference when lining up captions, as misalignment of any
horizontal features here would be particularly noticeable, and of
course without a lot of needless complication anything electronically >generated would naturally be aligned in this way.
I suppose this made the picture a trapezium with its long axis
horizontal and all verticals, including the sides of the picture,
leaning slightly to the left. It's a good job I'm not a pedant or I
might have worried about this.
Rod.
Yes, an analogue raster is technically not a perfect rectangle, but a >>trapezium with a downward slope of 2/625 towards the right.
More complicated than that, if the top and bottom half lines are
considered part of the picture - as I'm pretty sure they were in the
original standards (and I think I have indeed seen actual material where
they were).
On Monday, October 11, 2021 at 4:33:46 PM UTC+1, Roderick Stewart wrote:
On Mon, 11 Oct 2021 13:17:51 +0100, "J. P. Gilliver (John)" <G6...@255soft.uk> wrote:
Yes, an analogue raster is technically not a perfect rectangle, but a >>trapezium with a downward slope of 2/625 towards the right.
More complicated than that, if the top and bottom half lines are >considered part of the picture - as I'm pretty sure they were in the >original standards (and I think I have indeed seen actual material where >they were).Yes, the half lines were picture lines, which does slightly complicate
what you would call the overall shape of the picture, but the downward slope of the lines is still 2/625 relative to the sides. This leaves
the dilemma of whether you consider it "correct" to make the raster
lines truly horizontal or the sides truly vertical, because whichever
you do, the other one will be slightly wrong.
Not nearly as "wrong" as the geometric distortions in real life in a typical domestic TV with a curved screen, imperfect scan coils,
inadequate EHT regulation and an ageing vertical output cathode
decoupling capacitor, but I think we're talking theory here.
Rod.The same sort of questions were being asked when the first CCD cameras were being introduced which of course fed perfectly horizontal 'pictures' to CRT sets. It was pursued for obvious reasons.
On Mon, 11 Oct 2021 13:17:51 +0100, "J. P. Gilliver (John)" <G6...@255soft.uk> wrote:
Yes, an analogue raster is technically not a perfect rectangle, but a >>trapezium with a downward slope of 2/625 towards the right.
More complicated than that, if the top and bottom half lines areYes, the half lines were picture lines, which does slightly complicate
considered part of the picture - as I'm pretty sure they were in the >original standards (and I think I have indeed seen actual material where >they were).
what you would call the overall shape of the picture, but the downward
slope of the lines is still 2/625 relative to the sides. This leaves
the dilemma of whether you consider it "correct" to make the raster
lines truly horizontal or the sides truly vertical, because whichever
you do, the other one will be slightly wrong.
Not nearly as "wrong" as the geometric distortions in real life in a
typical domestic TV with a curved screen, imperfect scan coils,
inadequate EHT regulation and an ageing vertical output cathode
decoupling capacitor, but I think we're talking theory here.
Rod.
On Mon, 11 Oct 2021 13:17:51 +0100, "J. P. Gilliver (John)" <G6...@255soft.uk> wrote:
Yes, an analogue raster is technically not a perfect rectangle, but a >>trapezium with a downward slope of 2/625 towards the right.
More complicated than that, if the top and bottom half lines areYes, the half lines were picture lines, which does slightly complicate
considered part of the picture - as I'm pretty sure they were in the >original standards (and I think I have indeed seen actual material where >they were).
what you would call the overall shape of the picture, but the downward
slope of the lines is still 2/625 relative to the sides. This leaves
the dilemma of whether you consider it "correct" to make the raster
lines truly horizontal or the sides truly vertical, because whichever
you do, the other one will be slightly wrong.
Not nearly as "wrong" as the geometric distortions in real life in a
typical domestic TV with a curved screen, imperfect scan coils,
inadequate EHT regulation and an ageing vertical output cathode
decoupling capacitor, but I think we're talking theory here.
Rod.
On Mon, 11 Oct 2021 13:17:51 +0100, "J. P. Gilliver (John)" ><G6JPG@255soft.uk> wrote:
Yes, an analogue raster is technically not a perfect rectangle, but a >>>trapezium with a downward slope of 2/625 towards the right.
More complicated than that, if the top and bottom half lines are
considered part of the picture - as I'm pretty sure they were in the >>original standards (and I think I have indeed seen actual material where >>they were).
Yes, the half lines were picture lines, which does slightly complicate
what you would call the overall shape of the picture, but the downward
slope of the lines is still 2/625 relative to the sides. This leaves
the dilemma of whether you consider it "correct" to make the raster
lines truly horizontal or the sides truly vertical, because whichever
you do, the other one will be slightly wrong.
Not nearly as "wrong" as the geometric distortions in real life in a
typical domestic TV with a curved screen, imperfect scan coils,
inadequate EHT regulation and an ageing vertical output cathode
decoupling capacitor, but I think we're talking theory here.
Rod.--
Are you sure about the 2/5xx? I agree that the start of the _next_ line
is 2/5xx below the previous one, but I think the slope of any one line
is - _by the standard_ - only 1/5xx, because the line from the other
field is supposed to fill in the gap. In practice it probably _was_ more
of a slope (closer to 2/5xx), as the vertical deflection was probably
trying to be linear (at least, I'm sure no set tried to make it
stepped), and the flyback was faster than the scan, so the end of the
line was probably closer - in a vertical sense - to the start of the
next line than the theoretical standard.
On 09/10/2021 13:19, NY wrote:
Exactly. The cue dot is not something that the viewer needs to be
aware of,
so it is odd that it was*ever*Â placed in the picture lines, even
going back
to analogue days.
Was it ever used as a cue to a remote OB where they might to have used a standard TV receiver?
One near here, was not even able to receive BBC2 (analogue) so fed BBC2
off air sound to the OB so they could be cued in.
Might be no longer necessary but I know that BBC OBs were great
believers in "belt and braces" with a bit of string in case they both
fail and it does not cost anything.
used for test signals like pulse and bar, and later on in colour 625, even a small section of colour bars included with some lines for teletext.
On 09/10/2021 13:47, MB wrote:
On 09/10/2021 13:19, NY wrote:
Exactly. The cue dot is not something that the viewer needs to be
aware of,
so it is odd that it was*ever*Â placed in the picture lines, even
going back
to analogue days.
Was it ever used as a cue to a remote OB where they might to have
used a standard TV receiver?
One near here, was not even able to receive BBC2 (analogue) so fed
BBC2 off air sound to the OB so they could be cued in.
Might be no longer necessary but I know that BBC OBs were great
believers in "belt and braces" with a bit of string in case they both
fail and it does not cost anything.
The cue dot was invented way back to enable remote sources to start on
'cue', primarily for VT and TK which needed to run off a 10.
It should be remembered that a visual cue was often more effective
than having yet another speaker listening to Network talkback. Witness
a remote studio doing a live, which was common in days gone by,
standing by with 4 cameras, VT, TK, and lots of talkback. Much simpler
to watch a monitor with a cue dot on it.
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