[rezzer]

Hi. I have recently bought a new 22" 1080p HDTV but when I watch it I get very bad headaches. Having looked into this I have discovered that I can watch 1080i TVs without getting headaches but get headaches when I watch 1080p TVs. Has anyone heard of this before and is there anything I can do to make watching a 1080p HDTV less painful ?

[diablo]

Never heard of that before.

I assume that you are watching blu-rays on it to get 1080p, is there a setting on the blu-ray to output 1080i ?

All broadcast TV (freeview/Sky/Virgin) is in 1080i as far as I know.

[chrisjr]

Some broadcasts are 1080p and others are 1080i. But I wouldn't have thought it would make that much difference as the display panel isn't really i or p (nearer to p if anything). Either format displays 25 pictures per second.

Or could it be that the TV's that don't give headaches are actually 100Hz or something like that so theoretically may have reduced flicker?

[Nigel Goodwin]

Quote:

Originally Posted by chrisjr

Some broadcasts are 1080p and others are 1080i. But I wouldn't have thought it would make that much difference as the display panel isn't really i or p (nearer to p if anything). Either format displays 25 pictures per second.

Or could it be that the TV's that don't give headaches are actually 100Hz or something like that so theoretically may have reduced flicker?

No flicker on LCD's as they aren't scanned anyway.

In the original HD tests done I understand there were problems for a few people with headaches etc. using 720P50, which was one of the reasons it isn't used here.

[call100]

We need more information....Distance from set, lighting, settings etc. It's not an unknown phenomenon, but, a lot of headaches are caused by other influences rather than purely the 1080p..

[diablo]

Quote:

Originally Posted by chrisjr

Some broadcasts are 1080p and others are 1080i. But I wouldn't have thought it would make that much difference as the display panel isn't really i or p (nearer to p if anything). Either format displays 25 pictures per second.

Yes they've secretly changed some broadcasts since I last checked.

Though I think my HD freeview box converts things to progressive anyway.

[technologist]

All flat panels output progressive .....
So your TV is displaying 1080P no matter what you put into it .
All broadcasters output 1080i except freeview HD which occasionally codes it 1080P on a frame by frame basis .

If you have a stb you could see if making it output the opposite of what is giving you headaches ...
So that the conversion to progressive is done in the TV ....

[cornishpasty1]

To get into 3D we switched from LCD to plasma.
Apart from the murky dull pictures the Panasonic delivered my wife got headaches watching it .
SO we swapped it for an LED and all is well - no headaches and a return for the wow factor of HD.
But I suspect your 22" won't be plasma anyway

[iangrad]

I can get eye strain but not headaches from watching even a 32"

1080 lines of TV picture as opposed to PC output in such a small 22" screen will be dreadfully fuzzy .

[meltcity]

I used to get headaches from my 40" Samsung LED, so I replaced it with a 42" Panasonic 3D plasma. No more headaches. So my experience is the exact opposite of that of cornishpasty1.

[cornishpasty1]

Quote:

Originally Posted by meltcity

I used to get headaches from my 40" Samsung LED, so I replaced it with a 42" Panasonic 3D plasma. No more headaches. So my experience is the exact opposite of that of cornishpasty1.

Except your ability to adjust the brightness and contrast to decent levels has now gone too.

Weird about these headaches

[Nigel Goodwin]

Quote:

Originally Posted by iangrad

I can get eye strain but not headaches from watching even a 32"

1080 lines of TV picture as opposed to PC output in such a small 22" screen will be dreadfully fuzzy .

I don't know quite how you came to that conclusion?, but it certainly won't, screen size only affects suitable viewing distances not picture quality.

A 22" is likely to be far sharper in practice than a larger set, because you're unlikely to be able to get close enough to a 22" to be able to see the 'defects' on a 1080 transmission.

[grahamlthompson]

Quote:

Originally Posted by iangrad

I can get eye strain but not headaches from watching even a 32"

1080 lines of TV picture as opposed to PC output in such a small 22" screen will be dreadfully fuzzy .

Eh

You can now get FULL-HD and higher res screens on Phones and Tablets. The picture quality can be awesome. Take a look at a ipad retina display

2048 x 1536 pixels

http://www.apple.com/uk/ipad/features/

[d'@ve]

Having amazingly high resolutions on a small screen is all very well but you do have to focus a lot closer, and presumably that could cause issues for some people.

So I wonder if the O/Ps problem is more related to the small screen size than the screen resolution or de-interlacing/non-interlacing. Close focusing ability and ease deteriorates in everyone anyway as we get older so a good pair of reading glasses bi focals or vari focals might be worth considering, for some.... i.e. a visit to the optician.

[Nigel Goodwin]

Quote:

Originally Posted by d'@ve

Having amazingly high resolutions on a small screen is all very well but you do have to focus a lot closer, and presumably that could cause issues for some people.

So I wonder if the O/Ps problem is more related to the small screen size than the screen resolution or de-interlacing/non-interlacing. Close focusing ability and ease deteriorates in everyone anyway as we get older so a good pair of reading glasses bi focals or vari focals might be worth considering, for some.... i.e. a visit to the optician.

It certainly sounds far more likely a reason - viewing from close enough to make HD worth while on a 22 inch is going to make your eyes strain if you're a little long sighted, as most people become as they get older.

[grahamlthompson]

Quote:

Originally Posted by d'@ve

Having amazingly high resolutions on a small screen is all very well but you do have to focus a lot closer, and presumably that could cause issues for some people.

So I wonder if the O/Ps problem is more related to the small screen size than the screen resolution or de-interlacing/non-interlacing. Close focusing ability and ease deteriorates in everyone anyway as we get older so a good pair of reading glasses bi focals or vari focals might be worth considering, for some.... i.e. a visit to the optician.

You mean like 1600 x 900 17" 16:9 laptop screen about 12" from my face I am typing this on. I use varifocals no problem in using my laptop or a Full-HD 10" Asus tablet. Blu-rays look brilliant on the Asus.

[d'@ve]

Quote:

Originally Posted by grahamlthompson

You mean like 1600 x 900 17" 16:9 laptop screen about 12" from my face I am typing this on. I use varifocals no problem in using my laptop or a Full-HD 10" Asus tablet. Blu-rays look brilliant on the Asus.

Well you wouldn't have, would you, if wearing the correct glasses! But we don't know about the O/P's situation so that was the point I wanted to make. Just something for the O/P to consider.

[call100]

It would seem the OP has lost interest.....

[fmradiotuner1]

I some times get headache from my 50 inch TV if watching with out lights on in dark.
Turning down the contrast helps a lot as does with the PC and laptop to.

[rezzer]

I would like to take this opportunity to thank everyone who replied to my question. You are wonderful people.

[drillbit]

Quote:

Originally Posted by chrisjr

Some broadcasts are 1080p and others are 1080i. But I wouldn't have thought it would make that much difference as the display panel isn't really i or p (nearer to p if anything). Either format displays 25 pictures per second.

in laymans terms..whats the difference between i and p

[grahamlthompson]

Quote:

Originally Posted by drillbit

in laymans terms..whats the difference between i and p

I will try to explain

Interlaced content basically derives from CRT (Cathode Ray Tube) TV.s.

Let's stick with Digital TV's 720 x 576 pixels.

On CRT TV's the picture is created by firing an electron beam at a screen where the beam creates a light output for a short period using light respondind phosphurs. Colour expands the idea using 3 electron beams to hit groups of Red, Green and phospurs. If you tried to use this system to scan a 1/25 second frame (UK standard) line by line, them of you started at line 1 by the time you got to line 625 the top line would have faded. Result would be a flickering mess.

Instead the signal was sent split into fields, each one captured in 1/50 second. Each one only recorded half the video info, and scanned onto the screen in the following order.

Field 1, say lines 1, 3, 5 etc, field 2,4, 6,etc.

As a result when displayed on a CRT you get a split image 1/50 second apart, The next screen scan will have the last field of the previous frame followed by the next half of the next frame. In effect increasing the frame rate to 50 fps (ignoring the movement between fields in 1/50 second for fasr moving content)

Progressive recording simply records lines 1,2,3 - 625 one after the other. Depending on the source and how the TV handles it there is no difference at all if the two fields of a interlaced transmission are derived fro the same image (say a movie scanned from a single frame of film, The video data is the same just in a different order.

As already explained LCD/Plasma displays are not scanned in the sense of CRT displays, the source has to be converted to a 25fps progressive display. Individual YV's will handle this process differently. Largely the reason some kit wiil deliver mich better pictures. The picture is not displayed as it is received.

There are no progressive picture sources on satellite (the kit does not generally support it)

The much much later DVB-T2 freeview-HD service was from the start designed to support 1080p25 content. Not as suggested in this thread on a frame by frame basis, Mpeg compression relies on sending a complete frame (I frame) followed by subframes recording only differences from the I frame. The wholes structure Iframe + subframes is known as a GOP (Group Of Pictures). Freeview-HD can dynamically switch between a interlaced GOP and a progressive GOP.

Sadly the advantages of progressive have been massively oversold by the industry, totally ignoring the other significant factors.

Framerate

1080P at 50/60 frames/second is normally accepted as the best quality (only if supported by a bitrate of around 28Mpbs - the only real source is high end video camcorders, and replay Is restricted to the latest AVCHD progressive compliant kit.

1080p24 (24 frames/second) . Great pictures thanks to the large capacity of BD media, (large bitrate more than compensates for the lower framerate of 1080p50/60)

720P50 at 1280 x 720 for much content can look better than 1080i50 content.

Bitrate

Digital Video is a compromise. It works by discarding information (lossy compression).. The more information you throw away, the worse the picture/audio is but you can fit more channels in the same space (channel 5 on satellite is very poor on satellite compared to Freeview - All the Channel 5 channels are carried on a single carrier frequency (Transponder) on satellite).

Advances in encoder do allow similar picture quality using lower bitrates, (Hence there is now space for 5 HD channels on Freeview)

[drillbit]

^^^^^^^^^^^^^^^^

thanks for that,

now can you put into laymans language in a nutshell

[chrisjr]

Quote:

Originally Posted by drillbit

^^^^^^^^^^^^^^^^

thanks for that,

now can you put into laymans language in a nutshell

To put it simply.

The image you see on screen is made up of several lines of pixels (picture elements). i and p refer to how those lines get transmitted and potentially displayed.

With i the picture is split into two sections, one made up from all the odd numbered lines and one from the even numbered lines. These two sections are then transmitted one after the other.

On an "old fashioned" telly the two sections are also displayed one after the other, the telly displays two "half" images instead of one whole image. But your brain just sees one image.

On a modern LCD telly the two halves are stitched back together and the whole lot thrown at the screen in one hit. So you get one whole image at a time instead of two half images.

With p you cut out the middle man as it were and just send the entire image in one go so no splitting it into two at the transmit end or stitching it back together at the telly.

[Nigel Goodwin]

Quote:

Originally Posted by chrisjr

With p you cut out the middle man as it were and just send the entire image in one go so no splitting it into two at the transmit end or stitching it back together at the telly.

Not exactly, no

i and P are signal standards, and don't apply to LCD or Plasma TV's, as they don't produce scanned images.

While people keep claiming the displays are 'progressive', this isn't really true, they are neither progressive nor interlaced (both of which require scanning).

But as far as LCD/Plasma go, BOTH interlaced and progressive signals are 'stitched back together' in order to display them - the only difference is in the order of the stitching.

In laymans terms though "you don't need to know"