Digital TV Banter

Digital TV Banter (https://www.digitaltvbanter.co.uk/forum.php)
-   uk.tech.digital-tv (Digital TV - General) (https://www.digitaltvbanter.co.uk/forumdisplay.php?f=4)
-   -   4k TV on Freesat or Freeview? (https://www.digitaltvbanter.co.uk/showthread.php?t=34439)

_Unknown_Freelancer_ August 5th 15 08:08 PM

4k TV on Freesat or Freeview?
 
"Andy Furniss" [email protected] wrote in message
o.uk...
_Unknown_Freelancer_ wrote:
Sorry, was a wee bit busy earlier.


"Andy Furniss" [email protected] wrote in message
o.uk...
_Unknown_Freelancer_ wrote:

The quality you see on HD Freeview equates to SD quality at
source. i.e. What you see on telly is only as good as broadcast
quality SD (at source) ever was.

I agree that the bitrates are too low, but on something like
park-run from below, a 10 mbit h264 is still looks better than a
de-interlaced scaled up raw 576i. I could try harder WRT
deint/scale quality - but I doubt that would really help. Maybe
the source is not up to modern standards? Those samples do seem to
get a lot of "research" done on them - but then I am just an
idly/lazily half interested amateur.



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


It's 2015 - I don't have an interlaced display any more!

De-interlace and scale is what my (and I guess most peoples) TV does to
25i I could let it do it or I can do it in s/w my self.


How do you know this?
Do you have the source code from the manufacturer?

Manufacturers spend a lot of time and effort over their kit before they put
it to market.
Ok, so there is the occasional lemon model, but on the whole, most kit does
what it says on the tin.

Just because an OLED screen only came out of the factory in January 2015,
does not mean it can not interpret an interlaced scan 'is as.
Without the source code, for all we know (when watching 1080i) it may well
actually only update all the odd lines in one pass, and then all the even in
the next.

In which case, leaving source interlaced stuff as interlaced IS the best
thing to do.

Let the equipment decide what to do with it.

As previously, SMPTE didnt make up their standards for fun.
And Im pretty sure the manufacturers didnt toss a coin when writing the code
to decide how it should handle different display modes.

And in 'scaling' you're again compromising your own pictures.
Once you scale, you've ruined your copy for good.
i.e. You resample all the colour spacing, you contrive any representation.

Again, leave it as you got it, let the screen decide what to do with it.

Leap forward fifteen years. Screens will still have backward
compatitibility, and will be capable of rediculous resolutions.... but at
that point in time the manufacturers will have better means of making older
formats work well on their screens.



Although I notice certain 'arty types' in sports production actually
add a 'film effect' to some items. Aparently its 'art'. ....with a
capital F me thinks!


Not filmic that would imply deint to 25p (eww) TV/me would of course do
50p.


No.
Because it still leaves Tx at 50i.
You're not going to change the whole transmission chain for one vt package,
are you?

Generally its an effect applied at the time of playout. It just removes one
field.
"In the old days" VT was sped up to 200%, recorded, and played back at 50%
to achieve the same result.



The key to its success was that it refreshed the screen (albeit at
half resolution) fifty times a second*. The same 'higher refresh
rate' rule applies today. It gives clarity in any fast motion, such
as sports.

*FWIW, the half resolution higher refresh rate was chosen at the time
because they couldnt get phosphor to glow long enough for a
progressive scan without producing flicker.

Source quality SD contains more detail than present DTT HD.


The part run samples I pointed to are source quality aren't they?


TL;DR!
But, I dont think thats relevant anyway.
Im comparing source SD to DTT 'HD'.
Lab test vs Real world.


Whatever I try I can't get the raw 576i to look as good as a 10mbit
encode of the 1080i.


But without the source HD material, how do you know what detail/definition
has been lost to compare?
Generally compression occurs by smoothing edges (loosing detail), and then
finding repeat patterns in a frame (which buggers up captions).


Different cameras of course (same lens), detail -

ftp://vqeg.its.bldrdoc.gov/HDTV/SVT_exports/README.txt


Please do not misunderstand this and interpret this as me saying SD
HD. Simply not the case. Its once a picture has gone through the

terretrial transmission chain.


I don't see why my 10mbit x264 encode should beat pro kit - assuming of
course they would give that much bitrate to similar content.



Because its compressed to ****e by Arqiva!
Because the broadcasters dont want to pay any more s!


A few years ago, someone at ITV49 had a great idea to make a
'reality' programme interactive by placing a QR code in the top
tight of the screen. It worked perfectly in the edit. The website and
chat rooms were all set up. Then the programme went to air.....
no-ones phone could interpret the QR code.... because it had been
compressed to a grey blur!

Some muppet just had not thought that one through, and its never
been seen since!

And this was something that wasnt even moving. It was a permanent
stationary graphic. At no time was there sufficient capacity to send
any definition detail. So it stayed as a grey smudge.


That is amusing, and I don't doubt that DTT bitrates are terrible. Back
when I had both analogue and DTT on a CRT it was plain to see people had
hairy arms etc. that disappeared on the mpeg2 version. Of course that
was SD - SD. I am still unconvinced that 702x576 even raw will beat HD
even if it is somewhat bitrate crippled.

Of course watching the raw 1080i25 is even nicer - but it still
needs de-interlacing and that + the shutter speed still means the
grass/snow in the foreground is blurred during the pan.



Again, why do you need to de-interlace ?? Wht are you intent on
de-interlacing? When SMPTE created these new standards they set
added interlaced for distinct reasons. i.e. They didnt do it for a
laugh, or while they were down the beer keller!


Reluctantly to halve the bandwidth while giving decent temporal res.


But you wont be halving the data rate.
I know its the other end of the spectrum, but the maths is still the same:
(or "math", if youre "murican")
1080i50 (1080 interlaced, 25 fps, alternate lines refreshed at 50fps) =
1.5Gb/s (because you are sending 1080/2= 540 lines 50 times a second)
1080p50 (1080 progressive lines, refreshed at 50fps) = 3Gb/s (because you
are sending all 1080 lines every 50 times a second)

So, unless you're converting 1080i50 (off air telly) to 1080p25, you are
doubling your data rate by converting to 1080p50.
......and ruining the source by deinterlacing it needlessly.

And it's precisely the same if you're doing this with SD off air.
Converting 576i to 576p doubles your data rate.



Do you pros still use interlaced displays then? At work/at home/for HD?



That matters not.
Each different person has a different job to do, so they only want a picture
to suit their needs.
Vision just need it to make sure its the right colour/exposure/black level
and back focused.
Sound... (HA).... just want to see what's going to air, and a clue as to
what's next.
VT.... same as above.
Production.... "wait, what?"

It matters not to anyone really.
If this job is 720p, all the tellys (what every they be) resync
automatically.
If the next is 1080i, same again.
A programme is not made for our viewing pleasure. We just want a picture to
meet our particular requirements.
Everything just works.
And thats the way its 'supposed to be' all the way down the transmission
chain.

BUT.... you may well notice the occasional f.cup with 'regional news'.
ENG have gone out and shot something, usually out of focus, and recorded
with more audio distorion than a Foo Fighters concert!
Content goes back to the edit, and the clown at the keyboard, who has a
non-linear (computer) edit in front of him, hasnt bothered to check it on a
proper telly.
i.e. They've only watched it on their computer screen.
When it goes to air any horizontal motion shivvers.... because they've got
the field dominance the wrong way round!


I mean surely most people now see interlaced on a progressive display =
it's de-interlaced. If I put my Panny plasma into an interlaced mode it
de-interlaces (motion adaptively). It doesn't become an interlaced
display. I can de-interlace in s/w to achieve the same effect on a
dumber display (my 1920x1080 computer monitor).


As per first point above, without manufacturers source code, how do you know
that just because your telly only fell of Dixons shelf yesterday, that it
still doesnt update the display in an interlaced fashion?


The shutter speed does not cause the grass to be 'blurred during the
pan'. There is 'motion blur', which is what occurs when the camera
moves. Super motion and HiMo cameras negate this because of their
increased aquistion frame rates, which is then played back at 50i.


OK - you are in the trade, but I do recall shutter speed getting a
mention in one of the BBC R&D high framerate papers.


Ah, BBC R&D!
Way back in the last century, they really used to know their onions, and
even make their own onions too!


And there is artificting blur, because the broadcaster has
compressed the source to VHS quality, and ALL the grass becomes one
green smudge. Because there is insufficient bandwidth to transmit a
reasonable amount of detail.

There is a distinct difference between the two.


Fair enough, though the blur on the raw 1080i25 park run is clearly not
the latter, though total mush it isn't.



But ITV37 is.
And this is the stuff they tell you is better 'because its in HD'.


At least UHD will avoid the de-interlace and in the future 120fps
help with the shutter speed blur.


DO NOT be so sure that any forthcoming UHD channels will transmit,
or even originate, at 120fps.

I know, and full well understand that is the intention, the long
term goal. But at present, its just about getting 4K out before the
other broadcasters do. Four thousand horizontal pixels in a
progressive scan constitutes UHD. 120fps does not constitute, nor is
a requirement of, UHD.

As with everything else, bits = pennies, hence not neccesarily
leaping straight to 120fps.


Yes, I'm not upgrading till it's the norm (if I live that long) :-)

I bet 10mbit hevc would look better than the same rate 264 on
parkrun -


No. HEVC macro block size is eight times bigger than that of h.264.
(64x64) Yes there would be far less data, but there would also be
far bigger square artificts*. Eight times bigger. *See also YouTube
2005.

but I would have to cheat as I don't think free lib/ffmpeg will
code interlaced yet.


Yes, it does.
http://x265.readthedocs.org/en/defau...-intra-options



CTRL+F 'interlace'


OK, I'll have to revisit that. I do recall there being an issue
somewhere, so I guess it is/was ffmpeg - possibly that it can't/couldn't
actually play interlaced properly as it is/was used to getting weaved
frames from decoders, not fields.


AFAIK, the only difference is an interlace flag on every other frame.
I think its '-show_frames' (or something similar) for ffmpeg to dump the raw
data.

An interlaced frame then only contains half of the full screen of lines. The
flag indicates odd or even.
Thus, half the data rate of progressive.



I know hevc just does fields anyway


According to the manual (above), it can do interlaced. Crazy, I
know, but it seems it will.


What I meant buy fields was it doesn't (AFAIK) do anything complicated
for interlaced like mpeg2/h264 did - like they really wanted not do
interlaced, but did simply = coding fields and nothing more.

- maybe deint first


You are obsessed with progressive scan!!!

I know 'its better', and just like 'garlic bread', 'its the future'.
But if something is sourced in an interlaced standard, and the
equipment you play back on can handle interlaced images, why ruin
it?


My TV de-interlaces, I can do the same (possibly better) to play back on
a monitor that doesn't.

to 50p wouldn't be cheating too much,


And in encoding to 50p you double the required data rate.


True - but then weaved frames are also "extra" complicated so I don't


No, they're not.
Its just half the lines, with a flag.

think it would need 2x bits for the sameq. It would be a different test
though.


but it's currently so slow I could never play it at full speed on
my old PC.

ftp://vqeg.its.bldrdoc.gov/HDTV/

for raw video + details of.


To be more specific I am looking at the 576i25 and 1080i25 park run
(converted to 420) - though watching 422 makes no difference, it
wouldn't be a fair test as I had to convert to 420 to make a
representative h264 anyway.

ftp://vqeg.its.bldrdoc.gov/HDTV/SVT_...ekas_Exports_/


Changing pixel format, or colour space, will make zero difference to
definition or detail contained within an image. It relates to
colour handling. i.e. How you record the brightness of three
neighbouring pixels.

Yes, some colour spaces are not compatible with some encoders. But
that was in mind when certain encoders were constructed.

Even reduced to 1:0:0 (monochrome), an image would still contain
detail, edge definition, and clarity. e.g. A graphic consisting of
words would still contain precise edge detail in monochrome, in
1:0:0. A moving shot of a pitch would still contain the detail and
definition of the playing surface.

Only once you push that through an inter-frame encoder, that is when
you loose detail. That is when graphics suddenly get an aura of
their own. (Derek Acorah not included.) By which I mean an extra
unintended pixel shadow 1 to 3 pixels wide around the whole edge of
any graphics.


Going back to my original point, that if anyone transmitted _source
quality_ SD now (using the same bandwidth which is applied to HD.
i.e. uncompressed SD), it would appear to contain more detail than
the DTT dog faeces we get presently.

Therefore, why, instead of nob waving, launching half cocked 4K, why
doesnt someone have the bright idea of transmitting 'better HD'??
"True HD" even?? It would save trucks full of money for all
concerned for a start!


Better HD yes - I am still not convinced it's quite as bad as SD, though
- maybe I don't watch enough TV (usually motorsport) - perhaps park run
is misleading (I obviously don't have access to much else to compare),
but to me 10mbit x264 HD wins over raw SD for that.



A 'lab test' is not as good as a 'real world' test.
Our real world test is FTA Freeview HD.
Compared to source HD, you're all being ripped off severely!

UHD will be an even bigger rip off, with even more detail lost!



_Unknown_Freelancer_ August 5th 15 08:11 PM

4k TV on Freesat or Freeview?
 
Dave W" wrote in message
.. .
On Mon, 3 Aug 2015 19:22:14 +0100, "_Unknown_Freelancer_" /dev/null
wrote: (amongst other things)

Any captions or graphics, any channel. They should all have distinct sharp
edges.
Look again, and you'll see a border around everything, about 1 to 3 pixels
wide.
....because the transmitted mpg stream doesnt have enough bandwidth to
detail the edges of graphics.

"HD" is not HD.
Yes, its 'High', lots of pixels and vertical lines, but no 'Definition'.

The quality you see on HD Freeview equates to SD quality at source.
i.e. What you see on telly is only as good as broadcast quality SD (at
source) ever was.

Thus, the 'digital tv' rip off.
Freeview HD does not look good.


My TV, fed from HD Freesat, has to have "sharpness" turned to zero to
get rid of the horrible borders and exaggerated detail. The HD looks
good to me. In fact too good, exposing the make-up applied to female
presenters to make them look good in SD.


So you're turning the detail down to zero, removing picture definition.
Its a safe bet your telly makes Mary Berry look twenty years younger!
......because in removing detail, youre removing definition.
You're applying a real time photo-shop!

So, what is the point of HD for you??
You are removing the 'D' from it.



_Unknown_Freelancer_ August 5th 15 08:31 PM

4k TV on Freesat or Freeview?
 
"Freeview HD looks good."

"...looks good" ????



The war, my lord, is lost!

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

Next time there's a field based sport on telly, watch it.
Instead of watching 'the action', watch the detail in the grass when the
camera moves around.

The grass turns to one big green VHS* quality mush. All the detail in the
grass disappears.
When I say VHS quality, I mean the tape you left in the deck for that
'emergency crash in to record' occasion!

The detail only returns to the grass when the camera stops moving.
....once the mpg encoding has enough bandwidth to restore picture detail.


As it happens we only bought a [small] Freeview HD TV (for the kitchen)
relatively recently. The picture on the HD channels is noticeably better
than SD.



'SMALL'
Pictures ALWAYS look better on a small screen.
.....like (in the old days) telly was alway a better picture when you were at
the caravan
.....because the screen is smaller, all the mistakes and artifacts are
smaller, much harder to notice.

iPlayer looks fantastic on my phone... with its 3" screen!

You could have a small telly for your living room, so you dont notice the
crap.
......but its smaller! No-one would do that.



Our main TV is Freesat and the smearing etc. that you mention does not
occur very much on that, however BT TV (over the internet) of a football
match suffered in exactly the way you describe.


Freesat has far more bandwidth that Freeview.
Therefore is not subject to rediculous compression, resulting in VHS
quality.




FWIW, UHD IS more than four times the bandwidth.


No it is four times the resolution.


I wrote the nugget above in reply to RMCs post on 3rd August:
"UHD is certainly no more than four times the bandwidth of 1080i, which is
broadcast in the teens of Mbps (SD usually less than half that)."

i.e. He didnt understand my point that 4K required so much bandwidth.

Correct, it is four times the resolution.
HD x 2 in each direction.

The SMPTE solution was to carve the picture in to quarters.
So a 4K video source has four video outputs. Each 1080p.
1080p requires 3Gb/s

Four images at 3Gb/s = 12Gb/s data rate for one 4K image.
Eight times the data rate for 1080i50 HD.



And you want to compress 12Gb/s down to teens of Mb/s ????
Just what do you think will happen to your detail? ....to your picture
definition?
You think it will be 'Ultra High' do you?


Well I am sitting in front of a 4k monitor running at 60Hz. The signal
comes down one DisplayPort cable and IIRC it can manage 4k @ 30Hz on HDMI.


Ah, Mac.
I have a universal solution to all Apple problems:
www.wickes.co.uk/p/139250

Display port (allegedly) has a 32Gb/s bandwidth
https://en.wikipedia.org/wiki/DisplayPort






UnsteadyKen[_4_] August 5th 15 10:06 PM

4k TV on Freesat or Freeview?
 

In article:

"_Unknown_Freelancer_" says...

So you're turning the detail down to zero, removing picture definition.
Its a safe bet your telly makes Mary Berry look twenty years younger!
.....because in removing detail, youre removing definition.
You're applying a real time photo-shop!

Oh give over, you have it totally arse about face, a setting of zero on
most TV sets turns the Photo Shoppish artificial edge enhancement
processing off.
Have you really never tried it?

http://hifi-writer.com/wpblog/?page_id=3517

--
Ken O'Meara

_Unknown_Freelancer_ August 5th 15 11:12 PM

4k TV on Freesat or Freeview?
 
"UnsteadyKen" wrote in message
...

In article:

"_Unknown_Freelancer_" says...

So you're turning the detail down to zero, removing picture definition.
Its a safe bet your telly makes Mary Berry look twenty years younger!
.....because in removing detail, youre removing definition.
You're applying a real time photo-shop!

Oh give over, you have it totally arse about face, a setting of zero on
most TV sets turns the Photo Shoppish artificial edge enhancement
processing off.
Have you really never tried it?

http://hifi-writer.com/wpblog/?page_id=3517

--
Ken O'Meara


Imagine you've got this analogue slider,
.....similar to the old 'colour' slider, where it was monochrome at one end,
just right somewhere near the middle, and comparable to LSD at the other
end.

So, to the right hand end it emphasises egdes, makes them more vivid.
In the middle, it displays what it received. Be that OTA or off a piece of
wire from another box.
To the left, it goes the other way. It smooths out edges, it un-emphasizes
them.
i.e. Removes detail.

In analgue telly it was an HF tweak.
Putting gain in emphasised vertical edges. Attenuating HF smoothed them out.

And you're winding it all the way down to remove/smooth over the crap caused
by DTT transmission chain.
As before, you removed the 'D' from 'HD'.




UnsteadyKen[_4_] August 5th 15 11:40 PM

4k TV on Freesat or Freeview?
 

In article:

"_Unknown_Freelancer_" says...

Imagine you've got this analogue slider,
....similar to the old 'colour' slider, where it was monochrome at one end,

So, to the right hand end it emphasises egdes, makes them more vivid.
In the middle, it displays what it received. Be that OTA or off a piece of
wire from another box.
To the left, it goes the other way. It smooths out edges, it un-emphasizes
them.
i.e. Removes detail.

Well yes, but the sharpness control doesn't have a left hand end, it

only has a middle and right hand, it starts at zero processing which
equals image displayed as received, it doesn't do minus zero.


--
Ken O'Meara

Phil Cook August 5th 15 11:49 PM

4k TV on Freesat or Freeview?
 
On 06/08/2015 00:12, _Unknown_Freelancer_ wrote:
"UnsteadyKen" wrote in message
...

In article:

"_Unknown_Freelancer_" says...

So you're turning the detail down to zero, removing picture definition.
Its a safe bet your telly makes Mary Berry look twenty years younger!
.....because in removing detail, youre removing definition.
You're applying a real time photo-shop!

Oh give over, you have it totally arse about face, a setting of zero on
most TV sets turns the Photo Shoppish artificial edge enhancement
processing off.
Have you really never tried it?

http://hifi-writer.com/wpblog/?page_id=3517

--
Ken O'Meara


Imagine you've got this analogue slider,
.....similar to the old 'colour' slider, where it was monochrome at one end,
just right somewhere near the middle, and comparable to LSD at the other
end.

So, to the right hand end it emphasises egdes, makes them more vivid.
In the middle, it displays what it received. Be that OTA or off a piece of
wire from another box.
To the left, it goes the other way. It smooths out edges, it un-emphasizes
them.
i.e. Removes detail.

In analgue telly it was an HF tweak.
Putting gain in emphasised vertical edges. Attenuating HF smoothed them out.

And you're winding it all the way down to remove/smooth over the crap caused
by DTT transmission chain.
As before, you removed the 'D' from 'HD'.


No, the sharpness slider is *adding* something to the received picture
across its whole range, except at 0 where you are seeing what is
broadcast.
--
Phil Cook

_Unknown_Freelancer_ August 6th 15 10:21 AM

4k TV on Freesat or Freeview?
 
"UnsteadyKen" wrote in message
...

In article:

"_Unknown_Freelancer_" says...

Imagine you've got this analogue slider,
....similar to the old 'colour' slider, where it was monochrome at one
end,

So, to the right hand end it emphasises egdes, makes them more vivid.
In the middle, it displays what it received. Be that OTA or off a piece
of
wire from another box.
To the left, it goes the other way. It smooths out edges, it
un-emphasizes
them.
i.e. Removes detail.

Well yes, but the sharpness control doesn't have a left hand end, it

only has a middle and right hand, it starts at zero processing which
equals image displayed as received, it doesn't do minus zero.


Its just a number
It is not a measure of anything.
Its just some means by which non-technical users can understand the how much
change to a filter setting has been applied

Reverting back to analogue.... what if a slider on one telly had markations
from 0 to 20
Then an identical telly had -10 to 10
And a further identical one had 1 to 11 ....this of course would be only
sold by Marshall amps to rock bands!

Zero difference between them.
All apply the same amount of gain/attenuation.
The numbers are no measure of anything, they're just there for the
non-technical human end user.





_Unknown_Freelancer_ August 6th 15 10:22 AM

4k TV on Freesat or Freeview?
 
"Phil Cook" wrote in message
...
On 06/08/2015 00:12, _Unknown_Freelancer_ wrote:
"UnsteadyKen" wrote in message
...

In article:

"_Unknown_Freelancer_" says...

So you're turning the detail down to zero, removing picture definition.
Its a safe bet your telly makes Mary Berry look twenty years younger!
.....because in removing detail, youre removing definition.
You're applying a real time photo-shop!

Oh give over, you have it totally arse about face, a setting of zero on
most TV sets turns the Photo Shoppish artificial edge enhancement
processing off.
Have you really never tried it?

http://hifi-writer.com/wpblog/?page_id=3517

--
Ken O'Meara


Imagine you've got this analogue slider,
.....similar to the old 'colour' slider, where it was monochrome at one
end,
just right somewhere near the middle, and comparable to LSD at the other
end.

So, to the right hand end it emphasises egdes, makes them more vivid.
In the middle, it displays what it received. Be that OTA or off a piece
of
wire from another box.
To the left, it goes the other way. It smooths out edges, it
un-emphasizes
them.
i.e. Removes detail.

In analgue telly it was an HF tweak.
Putting gain in emphasised vertical edges. Attenuating HF smoothed them
out.

And you're winding it all the way down to remove/smooth over the crap
caused
by DTT transmission chain.
As before, you removed the 'D' from 'HD'.


No, the sharpness slider is *adding* something to the received picture
across its whole range, except at 0 where you are seeing what is
broadcast.
--
Phil Cook


.....and you have the manufacturers source code??



_Unknown_Freelancer_ August 6th 15 10:23 AM

4k TV on Freesat or Freeview?
 

FTR, big feature posted on Broadcastnow.co.uk today about BT Sports
forthcoming 4K Sports channel


http://www.broadcastnow.co.uk/featur...091309.article




All times are GMT. The time now is 05:43 PM.

Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
SEO by vBSEO 2.4.0
Copyright 2004-2006 DigitalTVBanter.co.uk