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uk.tech.digital-tv (Digital TV - General) (uk.tech.digital-tv) Discussion of all matters technical in origin related to the reception of digital television transmissions, be they via satellite, terrestrial or cable. Advertising is forbidden, with no exceptions.

terrible confusion



 
 
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  #11  
Old March 9th 17, 12:33 PM posted to uk.tech.digital-tv
Ian Jackson[_6_]
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Posts: 48
Default terrible confusion

In message , Dave W
writes

"Paul Cummins" wrote in message
. uk...
In article ,
(R. Mark Clayton) wrote:

They weren't just a story - my parents bought a Bush TV supposedly
ready for UHF, but when 625 came it turned out there was no UHF
tuner inside!


Bit like Freeview "HD-Ready" TV's

True, but at least I can use my HD-Ready TV to display the output of my
Freeview HD tuner/recorder (2 at a jumble sale).


I'm still confused about HD Ready, HD and Full HD.
https://www.google.co.uk/?gws_rd=ssl...l+hd+differenc
e&*
We were thinking about getting a new telly, and I told my wife we had to
go for Full HD. During a subsequent trip to John Lewis to compare what
was available, I got the distinct impression that the best pictures were
actually on the HD Ready sets - which is obviously wrong!
--
Ian
  #13  
Old March 9th 17, 04:59 PM posted to uk.tech.digital-tv
Woody[_5_]
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Posts: 1,581
Default terrible confusion


"Ian Jackson" wrote in message
...
In message , Dave W
writes

"Paul Cummins" wrote in message
.uk...
In article
,
(R. Mark Clayton) wrote:

They weren't just a story - my parents bought a Bush TV
supposedly
ready for UHF, but when 625 came it turned out there was no UHF
tuner inside!

Bit like Freeview "HD-Ready" TV's

True, but at least I can use my HD-Ready TV to display the output of
my
Freeview HD tuner/recorder (2 at a jumble sale).


I'm still confused about HD Ready, HD and Full HD.
https://www.google.co.uk/?gws_rd=ssl...l+hd+differenc
e&*
We were thinking about getting a new telly, and I told my wife we
had to go for Full HD. During a subsequent trip to John Lewis to
compare what was available, I got the distinct impression that the
best pictures were actually on the HD Ready sets - which is
obviously wrong!
--




It is a bit of a con.

Full HD is 1920x1080 resolution with progressive scan, usually shown
as simply 1080p. 1080 is the number of horizontal lines of scan. For
this you need a HD LCD panel with 2M pixels.

HD ready usually means a resolution of 1366x768 (or thereabouts) but
will show a 1920x1080 interlaced scan. The LCD panel will have 1M
pixels which will subjectively be better than a standard definition
picture but not as good as 1080p.

HD can mean that the screen can show 720 lines which is better than
the default off-air standard definition of 576 lines but goes nowhere
near what HD is meant to be.

Progressive HD is best when there is a lot of static information in
the picture, such as a seated studio presenter. It can however suffer
problems with rapidly moving pictures such as football where
interlaced is better so the broadcasters tend to switch between
interlaced and progressive as necessary as the picture content
changes.

Watch out. It is a legal requirement in the UK that any TV with a
screen size of 32" or greater MUST have a Freeview HD tuner fitted,
but it does not mean that it must have a 1080p screen: conversely you
can get smaller screens that are 1080p but that do not have a Freeview
HD tuner. Anyone these days should buy a set with a 1080p screen and a
Freeview HD tuner, then you are future-proof.



--
Woody

harrogate3 at ntlworld dot com


  #14  
Old March 9th 17, 05:00 PM posted to uk.tech.digital-tv
R. Mark Clayton[_2_]
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Posts: 372
Default terrible confusion

On Thursday, 9 March 2017 12:33:54 UTC, Ian Jackson wrote:
In message , Dave W
writes

"Paul Cummins" wrote in message
. uk...
In article ,
(R. Mark Clayton) wrote:

They weren't just a story - my parents bought a Bush TV supposedly
ready for UHF, but when 625 came it turned out there was no UHF
tuner inside!

Bit like Freeview "HD-Ready" TV's

True, but at least I can use my HD-Ready TV to display the output of my
Freeview HD tuner/recorder (£2 at a jumble sale).


I'm still confused about HD Ready, HD and Full HD.
https://www.google.co.uk/?gws_rd=ssl...l+hd+differenc
e&*
We were thinking about getting a new telly, and I told my wife we had to
go for Full HD. During a subsequent trip to John Lewis to compare what
was available, I got the distinct impression that the best pictures were
actually on the HD Ready sets - which is obviously wrong!
--
Ian


HD Ready just meant it had an analogue tuner and would be able to receive digital. Along with HD these sets were usually just 1280x720.

Full HD is 1920X1080 - more than twice as many pixels.

Full HD is a much better picture, but if you are too far from the set it makes no difference.

4K is actually 3840x2160, like this monitor. Not much content yet, so I have not rushed out to buy a 4k TV, but the monitor is superb!
  #15  
Old March 10th 17, 04:24 AM posted to uk.tech.digital-tv
Bill Wright[_3_]
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Posts: 1,461
Default terrible confusion

On 09/03/2017 16:59, Woody wrote:

Anyone these days should buy a set with a 1080p screen and a
Freeview HD tuner, then you are future-proof.


Until the next thing!

Bill
  #16  
Old March 10th 17, 06:54 AM posted to uk.tech.digital-tv
Woody[_5_]
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Posts: 1,581
Default terrible confusion


"Bill Wright" wrote in message
news
On 09/03/2017 16:59, Woody wrote:

Anyone these days should buy a set with a 1080p screen and a
Freeview HD tuner, then you are future-proof.


Until the next thing!


Yes, OK, but the root technology is probably not going to change for
the life of a TV bought today, is it?

(Digs in cupboard to find glass orb.....)



--
Woody

harrogate3 at ntlworld dot com


  #17  
Old March 10th 17, 07:38 AM posted to uk.tech.digital-tv
Mark Carver[_2_]
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Posts: 220
Default terrible confusion

On 09/03/2017 16:59, Woody wrote:

Progressive HD is best when there is a lot of static information in
the picture, such as a seated studio presenter. It can however suffer
problems with rapidly moving pictures such as football where
interlaced is better so the broadcasters tend to switch between
interlaced and progressive as necessary as the picture content
changes.


TV broadcasts have been interlaced since the 1930s, for only one reason,
you are saving bandwidth to a factor of 1:2. Simple as that.

Flat screens are natively progressive devices, so somewhere along the
line you need de-interlace the signal. That's the point where artefacts
can, and do get introduced on interlaced material, notably fast moving
action.

DTT HD broadcasts in the UK, are dynamically switched on a GOP level
(every 12 frames) basis between 1080i50 and 1080p25 if the source
material allows, (i.e it's derived from film,has been mungled
into looking like film, or is a stationaly image (basically any
situation where both odd and even fields are the same) . p25 consumes no
more bandwidth than i50 of course, but it means that your screen
is not unnecessarily converting from i to p.

What we don't have on DTT, because it would consume twice the
transmission bandwidth (all else being equal) is 1080p50. However, that
does exist increasingly within the studio or OB truck internally, for
optimum quality, and to allow upscaling for inclusion in 4k broadcasts.

Progressive scanning certainly does not introduce motion artefacts per
se, it's the conversion to/from interlace that does that.

4K/UHD formats are progressive, they simply don't exist in an interlaced
form (thank god)


--
Mark
Please replace invalid and invalid with gmx and net to reply.
  #18  
Old March 10th 17, 10:00 AM posted to uk.tech.digital-tv
Paul Ratcliffe
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Posts: 2,396
Default terrible confusion

On Fri, 10 Mar 2017 07:38:43 +0000, Mark Carver
wrote:

DTT HD broadcasts in the UK, are dynamically switched on a GOP level
(every 12 frames) basis


GoP lengths are not fixed any more. A quick check of a couple of things
recorded a day or two ago shows them varying between about 10 and 40 frames.
  #19  
Old March 10th 17, 10:08 AM posted to uk.tech.digital-tv
Max Demian
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Posts: 3,666
Default terrible confusion

On 10/03/2017 07:38, Mark Carver wrote:
On 09/03/2017 16:59, Woody wrote:

Progressive HD is best when there is a lot of static information in
the picture, such as a seated studio presenter. It can however suffer
problems with rapidly moving pictures such as football where
interlaced is better so the broadcasters tend to switch between
interlaced and progressive as necessary as the picture content
changes.


TV broadcasts have been interlaced since the 1930s, for only one reason,
you are saving bandwidth to a factor of 1:2. Simple as that.


It's because effectively the image goes to black between frames, the
same as cine film, so you get flicker. Cine film images are each
presented twice to avoid flicker there.

LCD (and other modern) displays go directly from one image to the next,
so no flicker.

25fps (or so) is fast enough to avoid jerkiness of most moving images,
whereas you need 50fps (or so) to avoid flicker where frames go to black
in-between.

--
Max Demian
  #20  
Old March 10th 17, 10:27 AM posted to uk.tech.digital-tv
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Posts: 222
Default terrible confusion

On Fri, 10 Mar 2017 10:08:48 +0000
Max Demian wrote:
On 10/03/2017 07:38, Mark Carver wrote:
On 09/03/2017 16:59, Woody wrote:

Progressive HD is best when there is a lot of static information in
the picture, such as a seated studio presenter. It can however suffer
problems with rapidly moving pictures such as football where
interlaced is better so the broadcasters tend to switch between
interlaced and progressive as necessary as the picture content
changes.


TV broadcasts have been interlaced since the 1930s, for only one reason,
you are saving bandwidth to a factor of 1:2. Simple as that.


It's because effectively the image goes to black between frames, the
same as cine film, so you get flicker. Cine film images are each
presented twice to avoid flicker there.

LCD (and other modern) displays go directly from one image to the next,
so no flicker.


Well not entirely true. The pixels are row-column driven so in theory there
is tearing as the image changes from top to bottom as it driver reads out the
new frame but its far too fast for the human eye to see.

--
Spud

 




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