[mythtv-users] Component Video Output?
Cory Papenfuss
papenfuss at juneau.me.vt.edu
Mon Jan 17 07:27:16 EST 2005
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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