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#1 2010-05-21 22:46:25

XtrmGmr99
Member
Registered: 2009-04-14
Posts: 128

[SOLVED] Calculating physical dimensions of screen

Hello,

I'm setting up a HTPC that will eventually be using XBMC to stream content from my server. That's not the problem; the problem is my TV.

I have a Sony Bravia KDL-32EX400 LCD TV that I've hooked my HTPC up to. It's 31.5" diagonally, and has full 1080p (1920x1080 resolution).

When using the VGA inputs on the TV, the display is fine and dandy. However, when using HDMI, things get weird -- it's as if a bit of each side has been cropped off, almost as if the TV was in zoom mode (it's not). It seems that X server displays the correct resolution, however get the dimensions of the screen wrong:

$ xdpyinfo | grep dimensions
  dimensions:    1920x1080 pixels (1626x914 millimeters)

1626x914mm... it thinks I have a 72" TV! I wish! It also reports a 30x30 DPI.

Anyway, I went about calculating the true dimensions of the screen via the instructions here, and came out with 698x393mm. I edited my xorg.conf file to represent this change, rebooted, and... nothing. xdpyinfo still shows 1626x914mm...

How can I set it to the correct dimensions?

Here's my xorg.conf (generated by nvidia-xconfig or whatever, the only thing I've modified are the Monitor dimensions):

# nvidia-xconfig: X configuration file generated by nvidia-xconfig
# nvidia-xconfig:  version 1.0  (buildmeister@builder75)  Fri Mar 12 01:42:27 PST 2010

Section "ServerLayout"
    Identifier     "Layout0"
    Screen      0  "Screen0"
    InputDevice    "Keyboard0" "CoreKeyboard"
    InputDevice    "Mouse0" "CorePointer"
EndSection

Section "Files"
EndSection

Section "InputDevice"
    # generated from default
    Identifier     "Mouse0"
    Driver         "mouse"
    Option         "Protocol" "auto"
    Option         "Device" "/dev/psaux"
    Option         "Emulate3Buttons" "no"
    Option         "ZAxisMapping" "4 5"
EndSection

Section "InputDevice"
    # generated from default
    Identifier     "Keyboard0"
    Driver         "kbd"
EndSection

Section "Monitor"
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "Unknown"
    HorizSync       28.0 - 33.0
    VertRefresh     43.0 - 72.0
    Option         "DPMS"
    DisplaySize    698    393
EndSection

Section "Device"
    Identifier     "Device0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Device0"
    Monitor        "Monitor0"
    DefaultDepth    24
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

Thanks for any help! smile

Last edited by XtrmGmr99 (2010-05-22 00:07:04)

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#2 2010-05-21 23:02:57

falconindy
Developer
From: New York, USA
Registered: 2009-10-22
Posts: 4,111
Website

Re: [SOLVED] Calculating physical dimensions of screen

DisplaySize isn't what you're looking for. This is what xorg uses to determine the DPI of the monitor.

It sounds like you're having a fairly classic overscan issue. the nvidia-settings applet will let you adjust this.

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#3 2010-05-21 23:22:52

XtrmGmr99
Member
Registered: 2009-04-14
Posts: 128

Re: [SOLVED] Calculating physical dimensions of screen

Oh...

Well, even still, it's showing a physical size more than twice the actualy value and calculating the DPI as 30x30 (ideally, I'd like it to be around 100-120).

I'll take a look at nvidia-settings and see what I can find... Thanks. smile

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#4 2010-05-21 23:25:14

XtrmGmr99
Member
Registered: 2009-04-14
Posts: 128

Re: [SOLVED] Calculating physical dimensions of screen

Where exactly is this overscan setting? I'm not seeing it. >_>

EDIT: Also, if it makes any difference, the output on the card is actually DVI. I'm using a DVI-to-HDMI cable, and hooking it up to the screen via HDMI.

Last edited by XtrmGmr99 (2010-05-21 23:32:59)

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#5 2010-05-21 23:45:08

XtrmGmr99
Member
Registered: 2009-04-14
Posts: 128

Re: [SOLVED] Calculating physical dimensions of screen

Turns out my HDTV has an option in the settings called "Display Area". I changes it from "Normal" to "Full Pixel", and hat seems to have solved the overscan issue. smile

I'll try to force the correct DPI via the xorg.conf file; i'll report back here if i don't succeed. =P

Last edited by XtrmGmr99 (2010-05-21 23:46:12)

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