[mythtv-users] Nvidia vs. ATI video cards

[Bruce Markey]

Clyde Stubbs wrote:
> Right now this seems to be a politically charged question.
> What kind of display are you going to drive? That makes
> a difference. 
> 
> ATI cards are definitely acceptable or better. Of that
> I can assure you. I won't say anything about nVidia lest 
> I get jumped on :-)

Fair enough. Subjective arguments are not productive if it
is just one person saying 'I like this" and the other saying
'I like that'. However, I do want to point out the factual
differences between using an nVidia card with the 4363 driver
and ATI with the GATOS "devel" branch for tvout.

Two years ago I had four ATI cards and over the course of a
year and a half I converted to now have four nVidia cards.
I only used the GATOS "devel" driver and have never used the
drivers from ATI for tvout. I still had one Radeon installed
when these became available but it was an older model that was
not supported.

First, GATOS doesn't do tvout at all unless the "devel" branch
of the CVS source is used. To compile, you also need to download
and compile xfree86 source. nVidia has tvout support by just
running the install script. Note that this is just an annoyance
and not a reason to choose one or the other.

GATOS only supports 16 bit color. nVidia supports 24bit and can
be changed to lower if you'd like.

GATOS supports 800x600 and 640x480 only. The nVidia driver also
supports 1024x768 if the card model is capable (and most are).

GATOS displays in a fixed size underscan area leaving black borders
on most TV. This is a good thing if you are using just as a computer
but it's nice to fill the whole screen when watching video. nVidia
supports overscan adjustments so you can get the image to fill the
screen (this has been broken in versions since 4363 but it is rumored
that this will be fixed again in the next release).

GATOS/ATI has no API for information about when it is about to
refresh the image (vertical synchronization or vsync), therefore
the software can only try to update the framebuffer at regular
intervals and hope they update in lock step. However, the update
may come just before or just after the vsync causing a twitch in
motion (watch the crawler on CNN). nVidia has vsync information
so frames can be updated at the right time and the motion is much
smoother.

GATOS doesn't support all if the Xv picture settings controls most
notably, many cards don't support Hue adjustments.

Finally, (and this is a little subjective ;-). All of the nVidia
cards I have now do a better job of reproducing the true color
palette. Not just saturation level =) but shade and gradient. The
colors in the video look more real, less distorted. If I were to
rank them for color reproduction, my nVidia cards would be 1-4 and
the ATI card 5-8.

I'm writing this for the sake of the list and by no means to 'jump
on' you, Clyde. Just pointing out that using nVidia has been the
better choice for use with MythTV.

--  bjm