100 Hz TV & interlaced content

[ppera2]

I just thought about some aspects by displaying 50 Hz interlaced video on 100 Hz TV's. How exactly fields are drown on the screen (scanned)?
If it's like by standard TV, but at double speed, then we are in trouble with interlaced material - we have 1/100 sec between fields instead of required 1/50.
So, I think that each field should be displayed twice in order, then next field...This is still not perfect, because we not scan whole display in 1/50 sec, but only odd or even lines.

Newer TV's offer progressive scan, but I don't know is it only for progressive source, or such TV's perform some deinterlacing of interlaced video?

[Shinigami-Sama]

I would figure it displays hte frames twice
E.I
AA BB CC DD ect ect..
that way it is still 50hz jsut frame doubled
it should look the same as if it were ona 50hz screen

[Mug Funky]

i thought 100Hz teevs were always progressive scan... could be wrong though.

the ones i've seen in stores use relatively simple bob-deinterlacing, and the quality varies from brand to brand from no deinterlace at all (thus combed frames) to pretty advanced motion-adaptive techniques (ala kernelbob).

question: do 120Hz TVs exist in NTSC land?

[Shinigami-Sama]

I;ve seen one
a 42" plasma screen
but I past out from loking at hte price tag so I don't rembmer hte brand
but I saw it at future shop

[scharfis_brain]

most 100Hz TVs are still interlaced internally!

¹ -> Top Field
² -> Bottom Field
¤ -> interpolated Field (by bob() or so)

-----------------------------------------------> time
100 Hz Fields: A¹ A² B¹ B² C¹ C² D¹ D² E¹ E²
50 Hz Fields: a a¤ b¤ b c c¤ d¤ d e e¤


this is the reason, why some 100Hz TVs are really blurry!

[ppera2]

Interesting is that proud 100 Hz TV owners remained silent here... I'm expected replies from them, but now I see the reason.

Here are some 'impressions' : http://www.avforums.com/forums/archive/index.php/t-14453.html

[Sycho]

Originally posted by Mug Funky
question: do 120Hz TVs exist in NTSC land? negative.

[scharfis_brain]

Originally posted by Mug Funky
question: do 120Hz TVs exist in NTSC land?

how about about the abuse of a NTSC capable 100Hz PAL-TV?
they all do 120Hz with NTSC input

[Shinigami-Sama]

Originally posted by Sycho
negative.
wrong
I sen one in future shop once
it cost like $10000 CDN though
and I nearly passed out from that tag btw

[Sycho]

Originally posted by Shinigami-Sama
wrong
I sen one in future shop once
it cost like $10000 CDN though
and I nearly passed out from that tag btw
Could you post a model or a link, because there are many television that cost that amount and only do 60hz, there are no 120hz ntsc televisions.

[Mug Funky]

strange that there aren't any. perhaps that extra 10Hz was enough to stop people seeing flicker, and nobody ever needed to crank the refresh rate more than that. but i doubt it.

though, looking at a PAL TV with a largely white screen, you can tell why people would want 100Hz TVs. it can get quite annoying, the flickering. but i wouldn't have thought 10Hz makes much difference.

[Phanton_13]

the extra 10Hz is not the real reason for the flicker of PAL vs NTSC, the cause is in the "pixel fill rate", the image escaning in the TVs and the retention of images in the eyes. if you have a 25hz progresive image in a progesive TV, you can saw flicker, but if you display each frane 4 times without process it the ficker are gone. Is the same reason for what you don't saw flicker in a film in the teather, and if you saw the film in a teoricall 24Hz tv you can se it(very simple, in the film proyector the all pixels of a image are displayed at once, but in the tv each pixel of a image is draw in a secuence, this make that the black time of each pixel in the movie are very diferent to the time in the tv)

[theReal]

Is the same reason for what you don't saw flicker in a film in the teather, and if you saw the film in a teoricall 24Hz tv you can se it The reason why you don't see flickering in the movie theater is another one: modern projectors have a shutter that shortly interrupts the picture in the middle - the framerate is still 24fps but the flickering is 48 times/s. If you don't have this shutter in the porjector, the movie flickers a lot (like it was in the old days of cinema).
However in bright scenes you can still see flickering in the movie theater (just like on a 50Hz tv screen).

AFAIK 100Hz CRT tv sets just display the lines twice (u,u,l,l,u,u,l,l,...) that's why there are no negative side aspects to this technology except that the flickering is stopped (you don't see how much a 50Hz tv flickers unless you got used to a 100Hz tv...)

[Phanton_13]

all projector have a shutter and if don't have it you can't project a film, but the shutters in nowdais are very diferent form the old shutters, we can hace mecanical shutters( the classic) and LCD shutters( this are very better than the mecanical), in the projectos exists two tipe of mechanisms to drag each frame, they can be drag continuously the film and the ones that drag junping frame to frame, the first tend to produce a flickering due to a high darg time in the frames transition, the seconds tend to have a very sort dark time in the transition and this reduces the flickering due to transitions. At any framerate you can have flickering if you have a very long dark time in the frame transitions.

[Shinigami-Sama]

Originally posted by Sycho
Could you post a model or a link, because there are many television that cost that amount and only do 60hz, there are no 120hz ntsc televisions.
umm it was a I think 21" lcd tv
either 21 or 24"
16:9
if I remmber what it was called I would have put the link up already

[ppera2]

Originally posted by Phanton_13
all projector have a shutter and if don't have it you can't project a film, but the shutters in nowdais are very diferent form the old shutters, we can hace mecanical shutters( the classic) and LCD shutters( this are very better than the mecanical), in the projectos exists two tipe of mechanisms to drag each frame, they can be drag continuously the film and the ones that drag junping frame to frame, the first tend to produce a flickering due to a high darg time in the frames transition, the seconds tend to have a very sort dark time in the transition and this reduces the flickering due to transitions. At any framerate you can have flickering if you have a very long dark time in the frame transitions.

I'm afraid that you write here very unprowen things.
Projector which drags film continuosly would produce extremly vertically blurred pic.
Big framerate excludes long dark time...

[ppera2]

Originally posted by theReal
AFAIK 100Hz CRT tv sets just display the lines twice (u,u,l,l,u,u,l,l,...) that's why there are no negative side aspects to this technology except that the flickering is stopped (you don't see how much a 50Hz tv flickers unless you got used to a 100Hz tv...)

Could you give here some references? Descriptions about way for concrete models?

[theReal]

Could you give here some references? Descriptions about way for concrete models?I'm not sure about this, but it's the simplest and only 50Hz-compatible way I can imagine (they've been on the market for years, so there can't be any digital tricks).
At a friend's house I have watched a lot of tv, DVD and Playstation on a ~5 year old Philips 100Hz CRT tv set and I always found the picture quality really good and flicker free.

However there are people who claim you can see motion artefacts on 100Hz tv sets and on cinema screens because of the repetition of the same frame/picture (I never saw it on the 100Hz tv, maybe on the cinema screen)

I found a good thread about this here (http://www.avforums.com/forums/archive/index.php/t-17596.html)

[Phanton_13]

Originally posted by ppera2
I'm afraid that you write here very unprowen things.
Projector which drags film continuosly would produce extremly vertically blurred pic.
Big framerate excludes long dark time...

you tell the true for the projector which drags film continuosly, but for that reason is used a shutter, this types are the first types of projector an they are droped a long ago, and yes the big framerates tend to exclude long dark times or at least they distributes the dark times and make their effect less notificable, but I used a teorical proposition, that proposition are true but when bigger are the framerate we need a bigger relation betwen dark times and show times to saw the flickering.

[theReal]

all projector have a shutter and if don't have it you can't project a filmWhen I said "when the projector doesn't have this shutter..." I didn't mean early projectors had no shutter at all - I meant they didn't have a double shutter to increase the flicker rate to 48Hz. I said it the wrong way, so it sounded like there wasn't a shutter at all (which is of course not possible)

[Sycho]

Originally posted by Shinigami-Sama
umm it was a I think 21" lcd tv
either 21 or 24"
16:9
if I remmber what it was called I would have put the link up already ah, ya, no, I call bull sh*t.

[manono]

Take it easy there, Sycho. Don't be living up to your name. Wanna see a 72 Hz HDTV:

http://www.pioneerelectronics.com/pna/product/detail/0%2C%2C2076_4123_17578493%2C00.html

[reepa]

"umm it was a I think 21" lcd tv
either 21 or 24"
16:9
if I remmber what it was called I would have put the link up already"

But the refreshrate shouldn't matter at all with LCD technology, should it?


Wanna see a 72 Hz HDTV:

http://www.pioneerelectronics.com/p...78493%2C00.html

Nice, 10 bits per color channel. Too bad all the broadcasts are 8 bits per channel :P

[scharfis_brain]

But the refreshrate shouldn't matter at all with LCD technology, should it?

It matters, though!
Here in Europe we are getting all those crappy Japanese/US-American 60 Hz LCD-Displays, which entirely destroy the 50 Hz Video motion by Frame repetition or Frame blending.

Can be easily prooved with a quick walk through one of the larger electronic stores (Media Markt etc. here in Germany).
Just take a look at the scrolling texts of one of the News-Channels.

[zilog jones]

Hmm, it says it does 72Hz and uses fancy pulldown conversion and stuff, but what happens when you're watching 60Hz video material on it? If it converts that to 24fps or 72Hz, anything that isn't film will look hideous!

And yes, with LCDs and Plasmas, the refresh rate doesn't relate to flicker at all so it's not a problem. Then again de-interlacing is a problem as it seems none of them can do interlaced video properly. Also, with the case of LCDs, the response time is quite an important factor - you wonder why cheaper LCD TVs and projectors (or pretty much all of them made before last year) are so blurry? The respone time on a lot of them is only 25ms... take into account that 50Hz = 20ms and 60Hz = 16ms...

And yeah, most of them handle 50Hz in the most distgusting of ways

[Shinigami-Sama]

I dono why they even deinterlace in hte first place it seems to a smarter thing to leave it hte way it is and just double hte veritcal resoultoin to match but then again I don't make them
as for lcd resposne time my new moni which I watch interlaved stuff on with out deinterlacing looks fine with a response time of 14ms

I also saw that 72hz plasma online once I thought it was bs but I'm not so sure now
to bad it costs $14000 I assue thats american money too
thats about 1/3 year;s pay for me

[Sycho]

Originally posted by manono
Take it easy there, Sycho. Don't be living up to your name. Wanna see a 72 Hz HDTV:

http://www.pioneerelectronics.com/pna/product/detail/0%2C%2C2076_4123_17578493%2C00.html I knew about that one, but he said 120hz. And this plasma will do both 60Hz and 72Hz according to the pioneer rep.

[Shinigami-Sama]

now I rember
it was an lcd tv/moni
explains hte refreshrate and why it cost more than a small child also..
geez you;re finicy mate you;d thikn two Canadians would get along ¬_¬

[ppera2]

Originally posted by manono
Take it easy there, Sycho. Don't be living up to your name. Wanna see a 72 Hz HDTV:

http://www.pioneerelectronics.com/pna/product/detail/0%2C%2C2076_4123_17578493%2C00.html

Well, That 3:3 pulldown chip is for progressive, FILM source as it says in specs. It simply scans each frame 3 times, probably progressive, as monitors. At least I conclude it because of vertical upsize and fact that they says that no need for interpolation.

[ppera2]

Here is AVS script for generate syntetic, interlaced video clip from single picture:

Ani = ImageSource("E:\ToCropB.bmp", end = 119)
Ani = Ani.Addborders(98,0,0,0) #by need
Animate(Ani,0,119,"Crop",498,0,800,600, 0,0,800,600)
Loop(10,0,119)
AssumeFps(50)
#Progressive until here
SeparateFields()
SelectOdd()
Weave()


It is for PAL, generates 800x600, what is good for TV out.
As picture, I drown on black blackground one white vertical line, width 6 pix, and one at 45 degree, same color and width. Full
size is 1200x800, and lines start 408 pix hor. from left edge.
Something like this |\ , but lines touch at top.
At each frame we have advance of 4 pix from left to right, totally 498 pix by 60 frames. Interalacing is good visible on monitor.

I don't know anyone here to run it on 100 Hz TV, but will try soon on one old Sony, when I will bring him TV out cable.

Most interesting is how aslant line will look.

Note: to see it correct on TV you must set TV out res to 800x600, if your video card can only 640x480 then need to change video size. Of course play it in fullscreen without some vertical resize.
Important is to set TV out as primary display, else playback will not be synced with TV scan!

[reepa]

I dug up a technology magazine from 2003 with a review of a couple of 32" 100Hz TVs. The article explains how the 100Hz TVs work. The first 100Hz TVs from the late 80's just displayed each field twice. This apparently introduced judder to motion so during the mid 90s they added motion compensation. This motion compensation is still not (in 2003) perfect and with a lot of motion it introduces artifacts.

Also, since the scanning is still interlaced it is possible to see line flickering with fine details. Some models counter this by scanning the fields in a different order when there is no motion (this decreases the motion compensation quality since motion detection takes a part of the processor's time). When there is no motion, the fields are scanned in alternating order (odd field, even field, odd field even field), while the normal scanning mode is odd field, odd field, even field, even field (each field displayed twice).

Additionally, some tv models have 50Hz progressive mode, which obviously doesn't remove flickering (except for 25Hz line flicker), but eliminates the judder and suits better for progressive sources. I wonder how these TVs deal with film sources.

Since I haven't seen 100Hz interlaced TVs myself I can't comment on the judder, but I sure can't see it on my monitor when watching TV at 100Hz. Perhaps converting to progressive is the key. Do 100Hz progressive TVs exist anyway (at reasonable prices)?


edit: I forgot to add that all the 100Hz TVs (since late 80s) convert the video signal to digital and store it in memory which makes it possible to display it twice. I don't know if all-analog 100Hz TVs exist at all.

[SeeMoreDigital]

Originally posted by reepa
I dug up a technology magazine from 2003 with a review of a couple of 32" 100Hz TVs. The article explains how the 100Hz TVs work. The first 100Hz TVs from the late 80's just displayed each field twice. This apparently introduced judder to motion so during the mid 90s they added motion compensation. This motion compensation is still not (in 2003) perfect and with a lot of motion it introduces artifacts. The new 100Hz TV's have introduced "digital" processing (each analogue field/frame image is scanned and converted to a digital field/frame image), which is why it's possible to see artifacts, similar to the ones more commonly associated with digital images.

Personally I can't stand the images generated by many modern 100Hz TV's. They often look washed out (like they've been painted in water colour), loosing much of the fine detail. That said companies such as Philips and Sony do seem to have cracked this problem...

... Not that Sony are making any of their own CRT tubes anymore ;)


Cheers

[scharfis_brain]

the 'washed out' image is due to following reasons:
- 8 bit sampling precision in some TVs (banding!!)
- heavy temporal and SPATIAL (I hate spatial) denoising
- heave Edge Enhancements (super Halos around borders)

they call that technics 'Super Digital Image Enhancement'

that's why pure analogue 50Hz TVs still offer the most natural images.

[zilog jones]

Originally posted by SeeMoreDigital
... Not that Sony are making any of their own CRT tubes anymore ;)

They aren't?! That sucks. Who does make them then? Are they still good? Are they still aperture grilles, even?

I shouldn't be surprised though. I have two Panasonic TVs at home, and if you look through the gratings at the back of them you can see Philips stickers on the tubes...

[theReal]

They aren't?! That sucks. Who does make them then? Are they still good? Are they still aperture grilles, even?I think the difference lies in how many tubes of a production line a company uses and how many they return as b-grade (other companies might only use the b-grade for their tv sets...)

I recently heard that Metz (a German producer of high quality tv sets) only uses at most 75% of the a-grade tubes they get, the others are returned after quality check. That of course makes the tv sets a little more pricy...