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-   -   4k TV on Freesat or Freeview? (https://www.digitaltvbanter.co.uk/showthread.php?t=34439)

David Kennedy[_2_] August 9th 15 08:02 PM

4k TV on Freesat or Freeview?
 
On 02/08/2015 12:22, Michael Chare wrote:
4K TVs are becoming available and more reasonable prices and there are some 4k
internet streaming channels.

So when, if ever, will any of the Freesat or Freeview channels convert to 4K?


Surely for the foreseeable future 4k is going to be totally reliant on
upscaling the transmission or on 4k discs? [whenever they arrive although I
believe some Blu-ray is already 4k]

http://www.theregister.co.uk/2014/01/20/feature_4k_confusion_over_specs_and_standards/

http://www.techradar.com/news/home-cinema/high-definition/4k-tv-resolution-what-you-need-to-know-1048954

--
David Kennedy

http://www.anindianinexile.com

Andy Furniss[_3_] August 9th 15 10:16 PM

4k TV on Freesat or Freeview?
 
R. Mark Clayton wrote:
On Wednesday, 5 August 2015 21:02:39 UTC+1, Andy Furniss wrote:
R. Mark Clayton wrote:

FWIW, UHD IS more than four times the bandwidth.

No it is four times the resolution.


Yes, but the source bitrate is 8x as you have to account for
current HD only being 25 fps or 50 fields per sec. UHD doesn't use
interlacing so 50fps doubles the source bandwidth on top of the res
increase. This means for sport that the vertical res increase is
(more than?) 4 times HD. The "more than" may be debatable - but I
think interlaced gets extra filtering to prevent interline
twitter.


You are still thinking about building a rasterised image with the
picture built up in [alternate] lines every [other] frame time.


I was thinking more on the capture side than transmission/display.

I have no idea if it still applies in the world of HD kit, but
historically at least, interlaced would, at camera level, get some sort
of extra vertical low pass filter to prevent artifacts downstream.

Even today in s/w, by default, ffmpeg will low pass vertically if you
convert progressive to interlaced.


More recent methods send the full frame every so often and the
changes every frame time. This works great for static images or for
video where things in the view change, but can generate artefacts
when the camera pans or zooms.


R. Mark Clayton[_2_] August 10th 15 10:22 AM

4k TV on Freesat or Freeview?
 
On Sunday, 9 August 2015 19:40:42 UTC+1, _Unknown_Freelancer_ wrote:
"R. Mark Clayton" wrote in message

SNIP


SNIP



+Because its sold by the broadcasters as 'better/amazming/fantastic/pin
sharp/other generic superlative'.


4k is - I am looking at it.


There's a 4K station on air now?


No. I am looking at a 4k monitor. It is better (a lot better) than full HD (and there is a full HD panel right next to it and a 1600X1200 CRT next to that). It is pin sharp.

I am not going to rush out and buy a 4k TV, just because they have come on the market, but if my existing [full HD] failed then I would buy a 4k one.

No 4k content [yet], well just plug in one of these: -
http://www.rikomagic.com/en/product/...59_pid_19.html



....when its not.


Freeview HD at 4K might not be.

Freesat at 4k might be as long as they give a whole transponder to each
channel.

Thus, it is a lie, a rip off.


Watched Sunday Brunch on Freeview HD earlier. (Yes, I know, ironic! eyes
roll It was sunday morning and my head was fried! )
During 'settee' interviews was annoyed by the false halo added to
interviewees caused by the brightly coloured wall behind them.
.....'transmission chain artifacts'.


You sure your TV is set up right?


Yes.


Not from the results you describe, but there is some "uprated" SD out there.

Brian Gregory August 12th 15 07:06 PM

4k TV on Freesat or Freeview?
 
On 03/08/2015 12:07, _Unknown_Freelancer_ wrote:
"Michael Chare" wrote in message
...
4K TVs are becoming available and more reasonable prices and there are
some 4k internet streaming channels.

So when, if ever, will any of the Freesat or Freeview channels convert to
4K?

--
Michael Chare


4K ....over Freeview?
One hopes you are 'having a laugh'. Seriously.

Consider that this stuff originates at 12Gb/s.
Tweleve gigabits of data, per second.
In comparison, present HD originates at just under 1.5Gb/s.

And to compress this enough so that its transmittable over freeview, you
would have to dispense with so much information that you would render 'UHD'
pointless.


You could use a whole DVB-T2 multiplex and the H.265 codec.

It would arguably be a better redition of 4K than the current HD
Freeview is of 2K.


i.e. The loss in quality would be so bad that it would be comparable to
existing HD. Therefore, just what is the point?

The only way to transmit 'acceptable' UHD is either usings serveral channel
spaces over satellite, or proper* broadband.
* meaning something better than BTs standard twisted pair phone line. Either
the co-ax that Virgin is installing, or fibre from both BT and Virgin.

4K over Freeview?
Hopefully, never.



--

Brian Gregory (in the UK).
To email me please remove all the letter vee from my email address.

Brian Gregory August 12th 15 07:11 PM

4k TV on Freesat or Freeview?
 
On 03/08/2015 19:22, _Unknown_Freelancer_ wrote:

Freeview HD is.... (sorry, Ive run out of expletives) DOG ****E!


Then what tirade of unprintable words do you use to describe Freeview SD?

All I know is that Freeview HD is way way better than Freeview SD.

--

Brian Gregory (in the UK).
To email me please remove all the letter vee from my email address.

Brian Gregory August 12th 15 07:17 PM

4k TV on Freesat or Freeview?
 
On 04/08/2015 20:42, _Unknown_Freelancer_ wrote:


Why would you de-interlace 576i? At all?
If you want to intentionally make PAL look bad, you de-interlace it.


Modern displays that don't just flash light as the electron spot passes
the pixel on the screen do not display motion properly unless you
de-interlace. You see double images as things move.

--

Brian Gregory (in the UK).
To email me please remove all the letter vee from my email address.

_Unknown_Freelancer_ August 12th 15 08:31 PM

4k TV on Freesat or Freeview?
 
"Brian Gregory" wrote in message
...
On 04/08/2015 20:42, _Unknown_Freelancer_ wrote:


Why would you de-interlace 576i? At all?
If you want to intentionally make PAL look bad, you de-interlace it.


Modern displays that don't just flash light as the electron spot passes
the pixel on the screen do not display motion properly unless you
de-interlace. You see double images as things move.

--


You're an "expert".



_Unknown_Freelancer_ August 12th 15 08:38 PM

4k TV on Freesat or Freeview?
 
"Brian Gregory" wrote in message
...
On 03/08/2015 19:22, _Unknown_Freelancer_ wrote:

Freeview HD is.... (sorry, Ive run out of expletives) DOG ****E!


Then what tirade of unprintable words do you use to describe Freeview SD?

All I know is that Freeview HD is way way better than Freeview SD.



Point.
Missed.




By a considerable distance.


My point is that SOURCE SD contains more detail than DTT Freeview HD.

"SOURCE SD".
i.e. As its recorded on DigiBeta cassette.
i.e. Uncompressed.


Of course Freeview HD is better than Freeview SD.
As soon as the analogue channels were switched off, they turned the SD bit
rates right down.... because then no-one had anything to compare digital SD
to any more.
i.e. No-one could say "this digital stuff is worse than the old stuff." The
proof had been switched off!

The secondary purpose of turning the SD bit rate down was to make everyone
think HD was therefore wonderful.
"Well.... its got to be hasnt it? Its better than that digital SD."

A third reason for turning the bit rates down was to free up bandwidth for
more channels.



So obviously, Freeview HD _IS_ better than Freeview HD.
But if they actually transmitted SD at source quality... which TBH, wouldnt
take much doing, it is my opinion that it would contain more detail than the
over compressed VHS quality the public is being sold as "HD" over DTT.


Read the thread before you wade in with statements like that.
Might prevent you looking a fool.



_Unknown_Freelancer_ August 12th 15 08:42 PM

4k TV on Freesat or Freeview?
 
"Brian Gregory" wrote in message
...
On 03/08/2015 12:07, _Unknown_Freelancer_ wrote:
"Michael Chare" wrote in message
...
4K TVs are becoming available and more reasonable prices and there are
some 4k internet streaming channels.

So when, if ever, will any of the Freesat or Freeview channels convert
to
4K?

--
Michael Chare


4K ....over Freeview?
One hopes you are 'having a laugh'. Seriously.

Consider that this stuff originates at 12Gb/s.
Tweleve gigabits of data, per second.
In comparison, present HD originates at just under 1.5Gb/s.

And to compress this enough so that its transmittable over freeview, you
would have to dispense with so much information that you would render
'UHD'
pointless.


You could use a whole DVB-T2 multiplex and the H.265 codec.

It would arguably be a better redition of 4K than the current HD Freeview
is of 2K.


Yes, you could.

But it would contain f.all detail.

Yes, you're transmitting the information for four times more dots, but there
just is not enough bandwidth available over DTT to allow it to carry any
level of Ultra High _Definition_. ....with particulat emphasis on the word
'Definition'.

All you're doing is making the picture bigger.
Not improving the quality.





i.e. The loss in quality would be so bad that it would be comparable to
existing HD. Therefore, just what is the point?

The only way to transmit 'acceptable' UHD is either usings serveral
channel
spaces over satellite, or proper* broadband.
* meaning something better than BTs standard twisted pair phone line.
Either
the co-ax that Virgin is installing, or fibre from both BT and Virgin.

4K over Freeview?
Hopefully, never.



--

Brian Gregory (in the UK).
To email me please remove all the letter vee from my email address.




Java Jive[_2_] August 13th 15 05:28 PM

4k TV on Freesat or Freeview?
 
On Wed, 12 Aug 2015 21:31:41 +0100, "_Unknown_Freelancer_" /dev/null
wrote:

"Brian Gregory" wrote in message

Modern displays that don't just flash light as the electron spot passes
the pixel on the screen do not display motion properly unless you
de-interlace. You see double images as things move.


This, as stated, is ambiguous and therefore perhaps not quite actually
incorrect, but it is at least highly misleading in that it implies the
problem is due to the modern displays, whereas actually the problem is
with the legacy CRTs and interlaced video!

First, I note that you supply no supporting *evidence* for your
assertion. Note the stress on the word 'evidence'. There is, for
example, this in Wikipedia, but it can't count as evidence because we
have no technical details as to how the picture was made. For
example, was it a photograph of a TV showing the scene? It doesn't
seem to be, because there are no tell-tale signs such as screen glare,
dust on the screen, Newton's rings, etc. Or was it a Print-Screen
grab off the creator's desktop while his PC was displaying paused
video? This seems to me to be much more likely, but then that doesn't
count as evidence, because it's not a picture of an LCD TV displaying
the picture as it natively would. And that's not to even mention that
the picture is a JPEG, which is a lossy compression format, so it is
certain that significant detail, that might have been important and
told us something useful, has been lost.

https://commons.wikimedia.org/wiki/F...r_wheel%29.jpg

We need something better ...

Around 2008, I created a myth-busting series of three pages for my
website:

http://www.macfh.co.uk/JavaJive/Audi.../CRTvsLCD.html

Note that the first page contains full technical details about how the
comparisons were made, including such as important details such as
camera shutter speed, which was 1/100s. This was the shortest time
that could still obtain a usable exposure with both types of TV while
still being fast enough in theory to capture the process of a field
being displayed.

To create those pages, I took many photographs such as these:

http://www.macfh.co.uk/Test/Piste-CRT.png (6.2MB)
http://www.macfh.co.uk/Test/Piste-LCD.png (7.2MB)

Note that the original photos were taken in Canon RAW format, not
JPEG, so that all detail seen by the camera was preserved, and that
these were next converted losslessly into TIFFs. As TIFFs cannot be
displayed in a browser, today I created the above lossless PNGs from
those original TIFFs. Therefore, AFAIAA, no detail has been lost from
that originally captured by the camera.

Note too that the vertical resolution of the image is comfortably more
than twice the 625 scan line frequency, which, according to sampling
theory, should therefore be enough to detect individual scan lines.

Note also that this is an aperture-grill CRT. It is possible that a
shadow-mask CRT would be different, but I suspect not significantly
so, as the few other images I've been able to find on the web showing
such material are essentially similar in appearance to those linked
above.

The second picture of the LCD displaying the same scene is there
merely for interest of comparison, but note that the forerunner
ski-racer on the piste has no motion artifacts such as combing.

However, only the first picture of the CRT displaying the scene is
needed to prove that the problem lies not with the LCD, but with the
CRT. The question is, now that you have an actual picture to work
from, can you see WHY?

The first and most glaringly obvious question is: Where are the
horizontal scan lines? If your explanation above is correct, in the
bright area of the picture, where the current field has recently been
drawn, we should see a series of interlaced bright (current field) and
dark (previous field) lines, but we do not. Even in the dark area of
the screen, where the camera could be argued to be less 'dazzled',
whatever that may be supposed to mean, and where we should be able to
see horizontal faint lines (previous field) interlaced with
near-as-dammit black lines (field before previous field), we still
cannot see individual horizontal scan lines. We have a camera with
sufficient vertical resolution to be able to capture them, yet,
although we can see quite clearly the vertical lines arising from the
aperture grille mechanism, horizontal scan lines are nowhere
individually discernible.

So what seems to be happening is that, whatever theory may say about
how CRTs work, in practice they are set up so that each horizontal
scan line is broad enough to overwrite exactly half of each
neighbouring line, so that when they are all drawn the picture is
contiguous, with no individual horizontal scan lines discernible. But,
effectively, this amounts to a halving of vertical resolution, and
THAT is why CRTs show less motion artifacts than equivalently sized
LCDs. It is not that the CRT displays a truer picture and the LCD is
creating artifacts - the artifacts have always been there, they are
an inherent part of interlaced video - rather it is that the CRT
hasn't got the vertical resolution to show these artifacts, but the
LCD has.

You can hardly blame the LCDs for displaying more faithfully the
source signals that are being fed to them, including any artifacts in
those sources. If you want them to display better pictures, feed them
better sources with fewer artifacts!

You're an "expert".


:-)
--
================================================== ======
Please always reply to ng as the email in this post's
header does not exist. Or use a contact address at:
http://www.macfh.co.uk/JavaJive/JavaJive.html
http://www.macfh.co.uk/Macfarlane/Macfarlane.html


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