[mythtv-users] TV choices - was: Could we install/runMythtv withoutX-windows

[Michael T. Dean]

PAUL WILLIAMSON wrote:

>  mtdean at thirdcontact.com 09/11/05 1:28 PM
> >
> > PAUL WILLIAMSON wrote:
> >
> >> How far away is your primary viewing area? I've been kicking
> >> around the idea of an LCD, but I sit about 14' away from where my
> >> TV is. The standard I've heard is 1" of TV width for every 5" of
> >> distance from the TV. Based on that, a 37" TV would be just
> >> about right.
> >
> > With HDTV, you can still have a very high-quality viewing
> > experience as close as 1" of TV width for every 2" of distance.
>
>  I can't afford that good of a viewing experience!

Neither can I, but I'm thinking of getting it, anyway.  ;)

> > The 5" is probably a better guess for SDTV. Unfortunately, if
> > you're watching both HDTV and SDTV on the same screen, you either
> > end up with small HDTV or low-quality SDTV. I figure I'll go for
> > the larger screen so that the low-quality SDTV makes me appreciate
> > the HDTV even more. :)
>
>  I don't really get this logic, because a decent HDTV will most likely
>  display the same quality SDTV signal as a good SDTV will, right?
>  What might make things better or worse is the distance from said TV
>  you view the picture.

Right, but distance has an impact on perceived size.  Therefore, if you 
view an HDTV (i.e. 1080p at 1920x1080 or 720p at 1280x720) show on a 61" 
TV from 60", you're close enough to see individual pixels.  If you view 
the same show from 120", you're far enough from the screen that you 
won't notice the individual pixels, so it will be a much better picture.

However, since SDTV (NTSC, which is typically considered about equal to 
640x480) has exactly 1/3 the pixels of 720p and almost 1/7 the pixels of 
1080p, watching an SDTV show on a 61" TV from 120", you'll be able to 
see individual pixels.  When you combine that with the visual artifacts 
that result from losses in the analog signal, the show picture quality 
will seem far worse than watching that same show on a much smaller TV or 
from much farther away.

It's about like taking a picture with a 640x480 camera and trying to 
print it at 8 1/2" x 11".  If you look at it while holding it in your 
hand, it doesn't look very good at all.  If you hang it on the wall and 
view it from a much larger distance, it doesn't look bad.  And, a 3.2MP 
or 4.0MP image printed at 8 1/2" x 11", will look good even upon close 
inspection.

Note that with EDTV/DVD (480p at 640x480 or 704x480), you'll still have 
the problem of low resolution, but since they are digital formats, the 
image should be clean (until the point where signal quality drops too 
much and you have too many errors to get any picture at all).  
Therefore, EDTV/DVD requires a smaller TV or a larger viewing distance 
than HDTV, but can generally be considered somewhere between HDTV and 
SDTV for recommended screen size/viewing distance combinations.

Also, if you buy one of the 1080p TV's (i.e. it has 1920x1080 pixels--as 
opposed to the 720p (1280x720 pixel) TV's that accept a 1080i and/or 
1080p input signal), you could in theory sit as close as 1" of TV width 
for every 1.5" of distance from the screen for a 1080i broadcast, but 
may notice recognizable pixels at that distance for 720p broadcasts 
(having half the pixels).

Here are a couple of buying guides that take the source of the material 
into account when determining TV sizes:

http://money.howstuffworks.com/tv-buying-guide1.htm
http://www.myhometheater.homestead.com/viewingdistancecalculator.html 
(you need to read the section "Interpreting the Results" on this page to 
understand the data)
http://reviews.cnet.com/4520-7608_7-1016109-2.html (they use 
"Wide-screen" to represent DVD/HDTV source--read the descriptions)

Few sources consider the difference between 720p TV's and 1080p TV's 
since the 1080p TV's have really just (re-) entered the market.

Mike