get current pixel clock size for Modeline (xorg.conf)

snitko · 11-06-2008, 10:12 AM

Case: I've got NEC 1970NX monitor, a desktop computer and a notebook. Desktop works fine, but notebook gives a blurry image on the monitor. I figured it's a pixel size problem, so I need to know its exact value on desktop pc. The problem is, it is somehow set automatically there (not mentioned in xorg.conf explicitly), so I need to get it.

Modeline generators don't work for me, they give wrong values.

Any ideas?

farslayer · 11-07-2008, 09:22 AM

cat /var/log/Xorg.0.log | grep -i clock

Code:

(II) RADEON(0): clock: 108.0 MHz   Image Size:  380 x 305 mm
(II) RADEON(0): Ranges: V min: 56  V max: 76 Hz, H min: 30  H max: 81 kHz, PixClock max 140 MHz
(II) RADEON(0): clock: 108.0 MHz   Image Size:  380 x 305 mm
(II) RADEON(0): Ranges: V min: 56  V max: 76 Hz, H min: 30  H max: 81 kHz, PixClock max 140 MHz
(II) RADEON(0): clock: 108.0 MHz   Image Size:  380 x 305 mm
(II) RADEON(0): Ranges: V min: 56  V max: 76 Hz, H min: 30  H max: 81 kHz, PixClock max 140 MHz

I believe 108.0 Mhz is the current PixClock

I tried using several other utilities (glxinfo, xrandr, xdpyinfo) to query the info but got nowhere.. turns out it was in the log.

Obtaining Modelines from Xorg Log

snitko · 11-07-2008, 04:52 PM

[QUOTE=farslayer;3334506]cat /var/log/Xorg.0.log | grep -i clock

Nope, mine shows only that:

Code:

(--) NVIDIA(0): NEC LCD1970NX (CRT-0): 400.0 MHz maximum pixel clock

And I also checked through the file manually, nothing really close to 'pixel clock size' except this line.

btw, I tried 108.0, but it's blurry.

Electro · 11-07-2008, 07:15 PM

It is blurry because it is using VGA not DVI-D. LCD requires a digital signal to display content. VGA is analog while DVI-D is digital. Converting analog to digital is not easy and it loses a lot of data in the process. Pixel clock is not what you are looking for. What you should be looking for is the native resolution of your screen and the refresh rate. Modeline generators should be used to help you make a modeline for a resolution and refresh rate that both your video card and monitor supports.

Pixel Clock is how fast all the pixels on the screen are painted at once. Higher resolutions will need a faster Pixel Clock. There is no such thing as Pixel Clock Size. There is DPI but it has no relationship to the quality of the picture. DPI is related with printing. DPI and PPI are the same thing. Higher DPI values will make the objects on the screen seem bigger while lower DPI values will make the objects on the screen seem small.