[mythtv-users] Component Video Output?

[Cory Papenfuss]

On Sun, 16 Jan 2005, Brad Templeton wrote:

> On Sun, Jan 16, 2005 at 07:11:42PM -0500, charlesrandle at cwjamaica.com wrote:
>> I would love to achieve the same with my SDTV that has component inputs, my
>> questions are:
>>
>> 1) Can this VGA -> Component conversion be done for SDTVs (Not HDTV) and if
>> so is it worth it , in that will there be a significant increase in image
>> quality ?
>
> The jump won't be that big.  It may not be much at all if you still are
> driving it with interlaced signals.
>
 	As usual, "it depends."  The TVOUT of many video cards blows 
chunks.  In order to make the frequencies compatible, a temporal rescaling 
(read: scanline conversion) must be done.  If you don't run with 480 
vertical resolution, another scaling is done.  From what I understand 
talking with an nvidia guy, the later nvidia cards/drivers have a 
"non-scaled" option that quietly kicks in if you request a standard 
supported resolution (e.g. 720x480).  With that, there may not be much 
advantage.  If you're running a tv-weird (e.g. 800x600 or 1024x768) 
resolution, there's one more layer of scaling that doesn't need to be 
done.

 	Since you mentioned over/underscanning it sounds like you may not 
be getting a 1:1 from the card.  My experience with "direct" VGA->TV 
conversion (NOT scanline conversion... just NTSC modulation) has been a 
*significant* increase in quality.  The pseudo-disadvantage is you need to 
program your modeline exactly.  You can still do over/underscanning, but 
you'll need to compute what to do manually from tweaking the modeline.  My 
TV doesn't even do 480p on the component in so I haven't tried that hard. 
If it did, I'd be using it.... progressive and full colors are *much* 
better than S-vid (e.g. xterm text is very readable and useable).

-Cory


*************************************************************************
* Cory Papenfuss							*
* Electrical Engineering candidate Ph.D. graduate student               *
* Virginia Polytechnic Institute and State University 			*
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