1920x1080 HDTV's? (was Re: [mythtv-users] bobdeint as output filter?)

Michael T. Dean mtdean at thirdcontact.com
Fri Dec 31 19:22:55 UTC 2004

While writing the below response, I started to wonder if there are *any* 
HDTV's available with 1920x1080 pixels.  More info below.  Keeping it 
short for those who just want to get to the point...  :)

On 12/31/2004 11:55 AM, Kyle Rose wrote:

>FWIW, I hate interlacing.  Interlacing was a technology devised to
>overcome a limitation of one kind of display technology and should
>have been deprecated with the advent of DTV.  Sorry to open THAT can
>of worms; just my $0.02. :)
The limitation: bandwidth.

If interlacing is no longer relevant in the age of digital TV, that 
implies that we now have unlimited bandwidth.  However, looking at ATSC 
high-definition TV, we have two primary modes:  720p (1280x720 at 60frames 
(fr)/sec and 60fields (fi)/sec) and 1080i (1920x1080 at 30fr/sec and 
60fi/sec).  (Yes, I'm ignoring the 30fr/sec with 30fi/sec, and the 
24fr/sec with 24fi/sec progressive modes available for 1080 and 720 
resolutions--not to mention the 12 other formats with lower resolutions.)

So, what is the purpose of 1080i?  Basically,it allows higher resolution 
at approximately the same bandwidth. 720p gives 921,600 pixels and 1080i 
gives 2,073,600 pixels--more than double the pixels of 720p.  However 
both 720p and 1080i take approximately 3MHz bandwidth, compared to 6MHz 
for NTSC (HDTV takes less bandwidth because of the compression that's 
possible with the digital signal).  So, if 1080i takes half the 
bandwidth of NTSC, why not make it 1080p at 6MHz?  Well, the broadcasters 
feel that the benefits of the progressive format are not worth the cost 
of the bandwidth--i.e. they would rather be able to transmit twice the 
number of channels (=2 times as much space for advertisements) in the 
bandwidth they have available.

Therefore, 1080i yields a much better picture than 720p for 
"slow-changing" scenes:  it is not ideal for sports or other shows that 
are composed primarily of fast-motion scenes.  Given that in most 
television shows--dramas, comedies, news, etc.--the fast-motion scenes 
are a very small percentage of the show, 1080i allows much better 
overall picture quality.

Of course, since nearly all HDTV's on the market have only 1280x720 
pixels, the quality benefit is chiefly available to those people using a 
computer to output to something other than a TV (i.e. high resolution 
monitors (such as WUXGA) or--for those with a lot of extra cash lying 
around--a projector with an extremely high optical resolution that can 
fully resolve 1920x1080, like the Runco DTV-1200 ( 
http://www.runco.com/OP_PA_dtv1200.html , MSRP $44,995.00)). 

But, wait!  My TV says it supports 1080i.  It does.  It accepts a 1080i 
signal, deinterlaces it, scales it down to 1280x720 pixels, and displays 
it.  Therefore, the TV's available today completely negate the advantage 
of 1080i (better picture quality) by scaling down to 1280x720 (which can 
even produce a lower-quality image than an unscaled 720p image).

So, are there any real 1920x1080 TV's out there?  I figure if I'm buying 
an HDTV, I'm not wasting money on a 1280x720 one, but I can't find any 
1920x1080 TV's.  Toshiba used to have one ( 
http://www.tacp.toshiba.com/televisions/product.asp?model=57HLX82 , MSRP 
$8999.99), but now that they've gone exclusively Digital Light 
Processing (DLP) (instead of the Liquid Crystal on Silicon (LCOS) they 
used for the 1920x1080 TV), it seems they only have 1280x720.  I'm not 
willing to spend on a projector more than twice what I spent on my car, 
so the Runco is out of the question.  Anyone know of any others?

It looks to me like I may be sticking with SDTV for several more years...


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