On Thursday 25 Sep 2003 4:24 am, Lance Cummings wrote:
> Richard, Derek & others,
>
> I did decide to experiment with the modelines, per advice. The first
> one of the three seems to be the best, almost without need of
> adjustment. The second one needs much more adjustment, and the
> third produces a totally green display, so something must be wrong
> there.
>
> I made the edit
>
> "Option "NoDDC"
>
> in the "Device" section
>
> per Derek's advice, before putting in the modelines.
>
> Now, I need some advice on operating xvidtune. I can adjust the
> screen with it, but the adjustment does not stay from one session to
> the next. So, I suspected I need to copy the new modeline generated
> by the adjustment, and paste that over the modeline I'm using. But
> I came up with the "green screen" again after doing that, so I need
> some advice on using this tool I think.
>
> The other problem I'm having is getting to 32 bit color. There are
> two places in the config file that reference it, here:
>
> Section "Screen"
> Identifier "screen1"
> Device "device1"
> Monitor "monitor1"
> DefaultColorDepth 24
>
> and here:
>
> Subsection "Display"
> Depth 24
> Modes "1024x768" "800x600"
> EndSubsection
>
> But when I edit both 24s to 32, I cannot startx. The error is no
> screen available. Advice on this appreciated.
>
> Lance
Good news about the ModeLine.
AFAIK translating the figures from xvidtune into a ModeLine should work OK.
Are you sure you put the mimbers in the correct order?
The first should be the pixelclock rate in Mhz.
The next 4 numbers can be read straight off the left hand side of the xvidtune
display from top down, and the final 4 numbers from the right hand side from
the top down.
As for 32bit colour depth I think I have given some bad info.
You cannot specify 32 bit depth in the XF86Config-4 file because the 'nv'
driver you are using does not support it.
I tried on my own computer using the 'closed source' 'nvidia' driver, and that
does not support it either, but I found this in the README file on the Nvidia
driver support site.
Quote
"DEPTH, BITS PER PIXEL, AND PITCH
While not directly a concern when programming modes, the bits used per
pixel is an issue when considering the maximum programmable resolution;
for this reason, it is worthwhile to address the confusion surrounding
the terms "depth" and "bits per pixel". Depth is how many bits of
data are stored per pixel. Supported depths are 8, 15, 16, and 24.
Most video hardware, however, stores pixel data in sizes of 8, 16, or
32 bits; this is the amount of memory allocated per pixel. When you
specify your depth, X selects the bits per pixel (bpp) size in which to
store the data. Below is a table of what bpp is used for each possible
depth:
depth bpp
===== =====
8 8
15 16
16 16
24 32
Lastly, the "pitch" is how many bytes in the linear frame buffer there are
between one pixel's data, and the data of the pixel immediately below.
You can think of this as the horizontal resolution multiplied by the
bytes per pixel (bits per pixel divided by 8). In practice, the pitch may
be more than this product due to alignment constraints."
/QUOTE
The difference between 24 bit and 32 bit colour depth is an 8 bit 'Alpha
channel' used to define translucency. If you are using the 'nvidia' driver,
then that alpha channel is enabled and you are in fact using what is known as
'32bit colour depth' in the Windows world.
Now I am not certain if the OpenSource 'nv' driver supports the alpha channel
or not. But I do know my screen looks slightly different if I use the nvidia
driver.
So it might be worth your while trying out the Nvidia driver.
It can be downloaded from here
http://www.nvidia.com/object/linux_display_ia32_1.0-4496.html
It comes with its own installer application. Just follow the instructions.
derek
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