On Thu, 28 Jul 2005, Ben Lancki wrote:
Cory,
I followed your various comments over the last year and built myself
the same homebrew VGA to SVIDEO converter that you have based on the
ad724. I'm using an nvidia fx5200. I've set my modeline to your
recommendation and adjusted the trimmer cap so that I'm getting a very
nice looking image on my tv:
ModeLine "720x480NTSC-I" 14.34945 720 760 824 912 480 484 492
525 interlace
Nicer than any tvout on any vid card I've ever seen... would you
agree? Just a quick question... did you use a crystal for the 3.58MHz
color subcarrier? Is that the trimmer cap you're talking about? I had a
bugger of a time getting it calibrated, as I don't have a spectrum
analyzer. I did have an RF generator, though. I ended up setting it by
tuning up 3.58xxxMHz into the RF generator, using it for scope sync, and
trying to "freeze" the output of my card.
Don't know if it's any better than the "turn until it looks best
on the TV," but at least I can say I tried. What I'd really like to do is
make a PLL/freq multiplier circuit of the HSYNC and use that for the
colorburst. Then it would be bone-fide NTSC (phase locked colorburst to
HSYNC). I haven't had time to do it yet, though.
I have two issues currently and I thought your insight might help me
figure this out faster. First, it appears that one of the interlaced
fields is being dropped. Was there a specific version of the nvidia
drivers that properly supports interlacing (what version do you use)?
I seem to recall comments that it worked in some versions but that it
was broken in later ones.
I had a bitch of a time getting a happy video card. It seems like
I could get 3 of the 4 requirements:
- Xv accel
- Interlaced support
- Low-freq support (for 480i modeline)
- No bugs in the driver
My latest is a 440MX I got from a friend. I don't recall the
driver version, but I'll try to remember to check tonight when I go home.
There was definately some flux in the interlace support in nvidia
driver-land awhile back. At that time I was using an ATI Rage128 and
most of the chatter was about HDTV modelines, so I wasn't paying attention.
The second problem I'm having is with the
DisplaySize. If I leave this value at default my myth menus look fine
but video is horizontally squashed slightly with black bars on each
side. I changed the DisplaySize to 640 480 to avoid this but when
mythfrontend starts, the menu text is incredibly small (like its
scaling something wrong). Could I get a copy of the pertinent areas of
your xorg.conf to see what you're doing. Thanks Cory.
IIRC, the DisplaySize is supposed to be units, not pixels... like
inches or cm. The ratio of them will set the aspect ratio mplayer/mythtv
uses to play, but it's also used to calculate the dpi of the Xserver. Now
that I RTFM, I see it's in mm. Try different values (in the same 4x3
ratio) and see if you can get the scaling right. I seem to remember I had
to set Mythtv to use extra-large fonts.
Hope that helps,
-Cory
--
*************************************************************************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
*************************************************************************
-------------------------------------------------------
SF.Net email is Sponsored by the Better Software Conference & EXPO September
19-22, 2005 * San Francisco, CA * Development Lifecycle Practices
Agile & Plan-Driven Development * Managing Projects & Teams * Testing & QA
Security * Process Improvement & Measurement * http://www.sqe.com/bsce5sf
_______________________________________________
ivtv-devel mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/ivtv-devel
