I have a CCTV system.

there are 10 ANALOGUE modulators so I get a 2x2 mosaic of the first 4
cameras on the 1st Mod and a 2x2 mosaic of the last 4 cameras on the 2nd
mod and then the next 8 mods is one each for the 8 cameras.

Now I use a 46 inch Plasma TV to view the 10 analogue channels. No
problems in 10 years.

This TV also coincidentally can do Freesat and Freeview.

I the replace all 10 analogue modulators with DVB-T modulators and this
is now combined into the Freeview feed.

Then within days I now have screen burn in, you can see faint lines of
the 2x2 mosaics and also of video edges such as between grass and paths.

So why did I not suffer from screen burn in when viewing CCTV over
analogue for 10 years but I now have screen burn in after a few days on
DVB't modulators showing *EXACTLY* the same video content from these 8
fixed cameras?

If it makes any difference the old mods were doing 675 line PAL 25 Hz interlaced whereas the new Mods are doing 1080p 50 Hz non-interlaced.

Stephen.

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On Thu, 23 Feb 2023 18:35:33 +0000, SH <i.love@spam.com> wrote:

I have a CCTV system.

there are 10 ANALOGUE modulators so I get a 2x2 mosaic of the first 4
cameras on the 1st Mod and a 2x2 mosaic of the last 4 cameras on the 2nd
mod and then the next 8 mods is one each for the 8 cameras.

Now I use a 46 inch Plasma TV to view the 10 analogue channels. No
problems in 10 years.

This TV also coincidentally can do Freesat and Freeview.

I the replace all 10 analogue modulators with DVB-T modulators and this
is now combined into the Freeview feed.

Then within days I now have screen burn in, you can see faint lines of
the 2x2 mosaics and also of video edges such as between grass and paths.

So why did I not suffer from screen burn in when viewing CCTV over
analogue for 10 years but I now have screen burn in after a few days on
DVB't modulators showing *EXACTLY* the same video content from these 8
fixed cameras?

If it makes any difference the old mods were doing 675 line PAL 25 Hz >interlaced whereas the new Mods are doing 1080p 50 Hz non-interlaced.

Stephen.

675?? do you mean 576i, (traditionally called 625 lines if you include
the VBI)

Is the displayed contrast, or overall brightness, significantly higher
from the digital source?


--
Graham.
%Profound_observation%

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

On 23/02/2023 19:40, Graham. wrote:

On Thu, 23 Feb 2023 18:35:33 +0000, SH <i.love@spam.com> wrote:

I have a CCTV system.

there are 10 ANALOGUE modulators so I get a 2x2 mosaic of the first 4
cameras on the 1st Mod and a 2x2 mosaic of the last 4 cameras on the 2nd
mod and then the next 8 mods is one each for the 8 cameras.

Now I use a 46 inch Plasma TV to view the 10 analogue channels. No
problems in 10 years.

This TV also coincidentally can do Freesat and Freeview.

I the replace all 10 analogue modulators with DVB-T modulators and this
is now combined into the Freeview feed.

Then within days I now have screen burn in, you can see faint lines of
the 2x2 mosaics and also of video edges such as between grass and paths.

So why did I not suffer from screen burn in when viewing CCTV over
analogue for 10 years but I now have screen burn in after a few days on
DVB't modulators showing *EXACTLY* the same video content from these 8
fixed cameras?

If it makes any difference the old mods were doing 675 line PAL 25 Hz
interlaced whereas the new Mods are doing 1080p 50 Hz non-interlaced.

Stephen.

675?? do you mean 576i, (traditionally called 625 lines if you include
the VBI)

Is the displayed contrast, or overall brightness, significantly higher
from the digital source?

sorry finger trouble!

The DVR has composite video loop through for all 8 cams so its analogue
625 line 25 Hz interlaced to the analogue modulators

The new DVB-T modulators are fed from HDMI (I have TVI to HDMI
converters) so this is the 1080p 50 Hz.

--- SoupGate-Win32 v1.05
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SH wrote:

So why did I not suffer from screen burn in when viewing CCTV over
analogue for 10 years but I now have screen burn in after a few days on
DVB't modulators

Different darkest-black to lightest-white levels, is one equivalent to
the 16-240 range and the other 0-255 range?

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

"Andy Burns" <usenet@andyburns.uk> wrote in message news:k5pu7qFsag2U1@mid.individual.net...

SH wrote:

So why did I not suffer from screen burn in when viewing CCTV over
analogue for 10 years but I now have screen burn in after a few days on
DVB't modulators

Different darkest-black to lightest-white levels, is one equivalent to the 16-240 range and the other 0-255 range?

The lack of burn-in on the analogue source may be due to timing jitter. With analogue, the graphics and the image (assuming a static camera) will be
subject to small variations in timing, due to noise and analogue timing variations which will spread the effect if bright pixels horizontally by a small amount. With digital, a pixel at (x,y) in the image will always appear
at exactly the same place on the screen without any slight random variation over time.

Just a thought. I may be completely wrong ;-)

--- SoupGate-Win32 v1.05
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On 24/02/2023 09:20, NY wrote:

"Andy Burns" <usenet@andyburns.uk> wrote in message news:k5pu7qFsag2U1@mid.individual.net...

SH wrote:

So why did I not suffer from screen burn in when viewing CCTV over
analogue for 10 years but I now have screen burn in after a few days
on DVB't modulators

Different darkest-black to lightest-white levels, is one equivalent to
the 16-240 range and the other 0-255 range?

The lack of burn-in on the analogue source may be due to timing jitter.
With analogue, the graphics and the image (assuming a static camera)
will be subject to small variations in timing, due to noise and analogue timing variations which will spread the effect if bright pixels
horizontally by a small amount. With digital, a pixel at (x,y) in the
image will always appear at exactly the same place on the screen without
any slight random variation over time.

Just a thought. I may be completely wrong ;-)

That certainly makes sense, as I do see "ringing" on composite video
signals which is something I do not see on HDMI signals.

S.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

"NY" <me@privacy.invalid> wrote in message news:...

The lack of burn-in on the analogue source may be due to timing jitter.
With analogue, the graphics and the image (assuming a static camera) will
be subject to small variations in timing, due to noise and analogue timing variations which will spread the effect if bright pixels horizontally by a small amount. With digital, a pixel at (x,y) in the image will always
appear at exactly the same place on the screen without any slight random variation over time.

Apologies: "the effect *of* bright pixels horizontally".

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

Dynamic range of the video is greater than analogue?
Brian

--

--:
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...
briang1@blueyonder.co.uk
Blind user, so no pictures please
Note this Signature is meaningless.!
"SH" <i.love@spam.com> wrote in message news:tt8bll$1u7pl$2@dont-email.me...

I have a CCTV system.

there are 10 ANALOGUE modulators so I get a 2x2 mosaic of the first 4
cameras on the 1st Mod and a 2x2 mosaic of the last 4 cameras on the 2nd
mod and then the next 8 mods is one each for the 8 cameras.

Now I use a 46 inch Plasma TV to view the 10 analogue channels. No
problems in 10 years.

This TV also coincidentally can do Freesat and Freeview.

I the replace all 10 analogue modulators with DVB-T modulators and this is now combined into the Freeview feed.

Then within days I now have screen burn in, you can see faint lines of the 2x2 mosaics and also of video edges such as between grass and paths.

So why did I not suffer from screen burn in when viewing CCTV over
analogue for 10 years but I now have screen burn in after a few days on
DVB't modulators showing *EXACTLY* the same video content from these 8
fixed cameras?

If it makes any difference the old mods were doing 675 line PAL 25 Hz interlaced whereas the new Mods are doing 1080p 50 Hz non-interlaced.

Stephen.

--- SoupGate-Win32 v1.05
* Origin: fsxNet Usenet Gateway (21:1/5)

"SH" <i.love@spam.com> wrote in message news:tta27g$1u7pl$4@dont-email.me...

On 24/02/2023 09:20, NY wrote:

"Andy Burns" <usenet@andyburns.uk> wrote in message
news:k5pu7qFsag2U1@mid.individual.net...

SH wrote:

So why did I not suffer from screen burn in when viewing CCTV over
analogue for 10 years but I now have screen burn in after a few days on >>>> DVB't modulators

Different darkest-black to lightest-white levels, is one equivalent to
the 16-240 range and the other 0-255 range?

The lack of burn-in on the analogue source may be due to timing jitter.
With analogue, the graphics and the image (assuming a static camera) will
be subject to small variations in timing, due to noise and analogue
timing variations which will spread the effect if bright pixels
horizontally by a small amount. With digital, a pixel at (x,y) in the
image will always appear at exactly the same place on the screen without
any slight random variation over time.

Just a thought. I may be completely wrong ;-)

That certainly makes sense, as I do see "ringing" on composite video
signals which is something I do not see on HDMI signals.

I'd forgotten about ringing: yes, that would smear point sources a bit so
their effect may have not have killed pixels in the same way as 100% reproducible, sharp digital signals.


I used to receive my TV through a cable feed when I lived in Bracknell. At
one time they were trying to eliminate roof-top aerials so they wired up all the estates with cable, which was available free of charge for channels that you would otherwise have received through an aerial, with a charge for additional cable-only channels. I noticed that the cable channels had a lot
of horizontal jitter: vertical lines were randomly wiggly and the ends of
the lines (if you turned off the TV's overscan) were similarly wiggly. I presume this was due to noise in the line-sync pulses meaning that the TV
was triggering its line scan at a variety of different times.

The same is true of analogue VHS recordings: especially noticeable if I
capture from VHS to MPEG, as compared (in the past) with capturing off-air
to MPEG.

Any device that produces its own raster (multiplexing multiple cameras to a single screen of thumbnails, or the SCART output from a Sky box, or BBC
micro with 625/25 output) may produce an inferior spec of signal compared
with a broadcast-standard signal (in the days when analogue was still broadcast).

I remember trying to record the output from my ZX81 and my Spectrum, and finding that the liberties that Sinclair had taken with the PAL signal were tolerated by TVs but not by VHS recorders.

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