Irish DTT Resolution

william

Hi all,

Does anyone know if Irish DTT will be broadcast in 480, 576 or 720 resolution?. I'm buying a TV and need to know this to work out what size of TV to go with. Sitting distance is 9 ft. Using this : http://www.hdtvtest.co.uk/Article/How-Far-Should-I-Sit.php

Many thanks,

Willie

watty

480 is USA / Japan only. 720p is practically only broadcast in USA, not Europe.

Saorview (Irish DTT ) is all 576i 25fps and 1080i 25fps.

The main 4 channels will gradually migrate to HDTV (1080i) during 2011 to 2014.

At 9ft you may want a 48" or larger TV. If you watch much 2.35:1 cinematic content on upscalled DVD or BD, 48" is an absolute minimum.

If you never watch films (many wider screen than WS TV thus need bigger screen) and you don't bother with glasses (but maybe should) and mostly watch Soaps and News, then 37" is perfect. If you are going to watch HD (1080i) then 37" is too small for 9ft. You'd not notice much increase in quality with HD.

To Cover all content from 576i SD TV to Cinematic 2.35:1 WS on Bluray, a projector with Zoom lens is perfection as that gives 36" to 72"

For mix of mostly 576i with some HD 1080i and no big BD (bluray) collection, then 48" is a perfect compromise.

For Mostly 1080i HDTV broadcast and load of Bluray, then 56" @ 9ft. You would find the "recommended" 60" to 65" on that site for 1080 @ 9ft a bit dominating in room and far too big for non-HD content.

william

Thanks Watty.

I'm very surprised to see a 46 inch being recommended for 9ft and 576i. The link I gave in the 1st post says that a 46 inch needs 12ft. What's the source of your data?

Thanks,

William

watty

I don't mention 46". If you mean 48", that's assuming some regular HD content.
if you mean 56", then that's assuming mostly 1080line HD.

See

   	[COLOR="Green"]576[/COLOR]   	720  	[COLOR="Red"]1080[/COLOR]
32"  	8'  	6' 	4'
37" 	[COLOR="Green"]10'[/COLOR] 	7' 	5'
40" 	10.5' 	8' 	5'
42" 	11' 	8' 	5.5'
46" 	12' 	9' 	6'
50" 	13' 	10' 	6.5'
52" 	13.5' 	10' 	7'
65" 	17' 	13' 	[COLOR="Red"]8.5'[/COLOR]

For 9' from http://www.hdtvtest.co.uk/Article/How-Far-Should-I-Sit.php
SD TV only, DVD only, no HD (576 lines) 37" is next closest. 32" is too small
HD TV only, BluRay Cinema only, All HD (1080 lines) 65" is closest listed.

But you will have a mix of HD and SD content. Hence 48" recommended as compromise size. Not too expensive, not too dominating.

See also http://www.techtir.ie/tv_radio/hdtv

Note that there is actually no difference in screen size that's ideal for 1080i and 1080p as for slow moving or still pictures those are the same resolution and detail. Most people can't see as much detail in fast moving objects, which is why in the 1930s the Scientists and Engineers came up with the idea of interlace as a compression scheme that saves 50% bandwidth and for most scenes has no effect on sharpness. On a Still there is zero difference. If the source was 24 fps 1080p (film) then a TV's de-interlace circuit will re-create perfect 1080p.

william

Thanks Watty, meant 48 inch sorry. Very useful info - will put it to good use.

William

mike65

How did people cope with 22" TVs up until the last 10 years? (I'm being sarcastic naturally)?

watty

well.. if you had money you bought a 26" even in 1970s

A 32" to 37" Widescreen is needed to replace a 26" or 28" 4:3 set.

The whole reason for developing HD is because in Japan and USA they had bigger screens (even 3 tube CRT rear projection) and NTSC Color 525 lines (480 visible) looks terrible on 36" 4:3 never mind 56"!

Ever wondered why HD is really stupid 1080 (visible) lines?

Japan had the earliest working [Colour] HDTV system, with design efforts going back to 1979. The country began broadcasting analog HDTV signals in the late 1980s using an interlaced resolution of 1035 or 1080 active lines (1035i) or 1125 total lines.

The Japanese system, developed by NHK Science and Technical Research Laboratories (STRL) in the 1980s, employed filtering tricks to reduce the original source signal to decrease bandwidth utilization. MUSE was marketed as "Hi-Vision" by NHK.

* Japanese broadcast engineers immediately rejected conventional vestigial sideband broadcasting for well-founded technical reasons.
* It was decided early on that MUSE would be a satellite broadcast format as Japan economically supports satellite broadcasting.

The German 1940s and French 1950s HDTV was only monochrome. Not Colour.

see http://en.wikipedia.org/wiki/Analog_HDTV#Multiple_sub-nyquist_sampling_Encoding_system_.28MUSE.29

MUSE would be 1035i (or 1080i, hence the origin of less than ideal 1080 for digital HDTV. 960p60 for USA and 1152i25 for Europe and 1152p48 worldwide would be better).

Normal eyesight is such that in Europe the 30% better resolution (for 576i vs 480i) means there is little value in HD on a 32" 16:9 screen (Widescreen) at typical viewing distance.