[mythtv-users] Nvidia Settings (was Super Frustration)

[Bruce Markey]

Ryan A. Carris wrote:
> On Fri, 25 Feb 2005 11:56:59 -0800, Bruce Markey <bjm at lvcm.com> wrote:
> (snip) 
> 
>>I decided to look into the alignment problem. In a long afternoon
>>of divide and conquer, I found a magic overscan value that put a
>>480 pixel image in 480 scan lines for the 4xxx driver. Of course,
>>the overscan changed with the 6xxx drivers and are now controlled
>>by the "nvidia-settings" tool. If the overscan value is set to 250
>>(actually anywhere from 243-250) it is pretty darn close if not
>>exactly 480 pixels on 480 scan lines. This means that by not scaling
>>and with accurate frame timing, only data from one of the recoded
>>fields is displayed per field refresh.
> 
> (snip)
> 
> Based on your suggestions, I played around with my settings last night
> to see if I could improve on the extremely poor s-quality I'm getting
> out of the FX5600XT (possibly a Gigibyte card) I put in last week. 
> Compared to the onboard Nforce2 quality I was getting, it sucked!  So,
> beware, I believe that it varies from manufacturer to manufacturer.
> and was really happy with the results, so I wanted to respond, so
> maybe more people would see your advice.
> 
> I'm not sure I could tell much difference by setting the overscan to
> 250.  It was just very slight on my card/tv.  But, setting this made
> me adjust my GUI size IN MYTH  SETTINGS/APPEARANCE down to ~540x750
> and set the offsets to X = 15 Y = 20 so that everything stayed on the
> screen.  Not a big deal.

Not surprising. The point is that to avoid interlace artifacts, there
needs to be a one to one relationship between the rows of pixels in
the X display area and the scan lines on the TV. You mention "down to
~540x750" which I assume is a typo =) and most likely means either
you were using 800x600 for your X display or you are in PAL land and
were not at somethingx576. I'll assume the former. You must use 640x480
and overscan of 250 (record at Nx480 and myth's overscan settings at 0)
to try to get each row of pixels into it's own distinct scanline. If the
image is scaled in any way, information from adjacent pixel rows will
be blended onto the same TV scan line.

>>In "nvidia-settings", set the flicker filter to 1, and sharpness to
>>about 6 to 8. Set "TV Saturation" to about 172 to 178. The last
>>one is important. I've found that both nVidia and ATI tvout tend
>>to bleed bright reds when the TV is set the same as for a TV signal.
>>The best solution I've found is to turn down the color on the TV set
>>to just below the point where reds pulsate, glow or bleed then turn
>>up this nvidia saturation control. Recording with higher sat would
>>distort the colors in the recording and the Xv saturation seems to
>>cause distortion also. However, the nvidia setting gives colors more
>>body without distortion until you are at a point where the colors are
>>cleanly overdriven.

> Now the Flicker and Sharpness adjustment made a BIG difference.  I'm
> now convinced that lowering these settings is an absolute must. 
> Scrolling text used to be fuzzy, but now is crisp -- almost too much
> with a harsh edge.

Sharpness is some nasty trickery and is actually degrading the image.
The edges are soft but they can look a little crisper by screwing with
the signal so it's a balancing act.

>  The Flicker Filter made the biggest difference.  I
> get a bit of flicker in the horizontal lines in the GUI, but that is
> expected on an interlaced TV.  To control this somewhat, I have my
> Flicker Filter set to ~12.

Here again it's a trade off. It's making the flicker less noticeable
by blurring horizontally.

> Turning up the Saturation helped a little to improve the vibrancy, but
> this card isn't a good judge of color.  I have a new MSI FX5200 coming
> today from newegg; will play more this weekend.

This for me was kind of a breakthrough. Before having this slider,
My colors were always pale and less dense than they should have been.
Turning up the TV color would bleed on intense colors, turning up
the recording sat distorted the recording image. Playing with the
chroma range in the 'adjust' filter is fun and can be useful but the
card seem to clamp the density of medium colors no matter what. Only
after turning up this setting have I truly been happy with the
palette of colors.

--  bjm