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#1 2021-10-04 15:19:03

Xwang
Member
Registered: 2012-05-14
Posts: 323

[Solved] TV connected with HDMI with wrong dimension

Hi to all!
I've a notebook and I often connect it to an external monitor or to a TV using HDMI.
When I connect to the external monitor xrandr -q reports the correct physical dimensions.
The TV instead reports wrong dimensions.
Is there a way to fix it so that xrandr "automatically" reports the correct values every time that specific TV is connected?

Last edited by Xwang (2021-10-06 07:34:24)


I'm still learning English so please excuse me if my English is not good enough and feel free to correct me via PM if you want.

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#2 2021-10-05 09:41:28

Xwang
Member
Registered: 2012-05-14
Posts: 323

Re: [Solved] TV connected with HDMI with wrong dimension

Meantime I've discovered that even with the laptop alone there is something strange because xdpyinfo and xrandr report different physical dimensions (xrandr's output being the correct one):

xdpyinfo | grep -i dimens
  dimensions:    1920x1080 pixels (508x285 millimeters)
xrandr -q
Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 16384 x 16384
eDP-1-1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 382mm x 215mm
   1920x1080     60.02*+  60.01    59.97    59.96    59.93  
   1680x1050     59.95    59.88  
   1400x1050     59.98  
   1600x900      59.99    59.94    59.95    59.82  
   1280x1024     60.02  
   1400x900      59.96    59.88  
   1280x960      60.00  
   1440x810      60.00    59.97  
   1368x768      59.88    59.85  
   1280x800      59.99    59.97    59.81    59.91  
   1280x720      60.00    59.99    59.86    59.74  
   1024x768      60.04    60.00  
   960x720       60.00  
   928x696       60.05  
   896x672       60.01  
   1024x576      59.95    59.96    59.90    59.82  
   960x600       59.93    60.00  
   960x540       59.96    59.99    59.63    59.82  
   800x600       60.00    60.32    56.25  
   840x525       60.01    59.88  
   864x486       59.92    59.57  
   700x525       59.98  
   800x450       59.95    59.82  
   640x512       60.02  
   700x450       59.96    59.88  
   640x480       60.00    59.94  
   720x405       59.51    58.99  
   684x384       59.88    59.85  
   640x400       59.88    59.98  
   640x360       59.86    59.83    59.84    59.32  
   512x384       60.00  
   512x288       60.00    59.92  
   480x270       59.63    59.82  
   400x300       60.32    56.34  
   432x243       59.92    59.57  
   320x240       60.05  
   360x202       59.51    59.13  
   320x180       59.84    59.32  
DP-1-1 disconnected (normal left inverted right x axis y axis)
HDMI-1-1 disconnected (normal left inverted right x axis y axis)
HDMI-1-2 disconnected (normal left inverted right x axis y axis)

Why?

EDIT:
Meantime I've solved this issue by forcing the dpi with which Xorg is started in rootless mode by sddm from 96 to 128 (which is the correct value for my laptop screen).

Last edited by Xwang (2021-10-05 11:48:08)


I'm still learning English so please excuse me if my English is not good enough and feel free to correct me via PM if you want.

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#3 2021-10-05 12:22:25

Lone_Wolf
Member
From: Netherlands, Europe
Registered: 2005-10-04
Posts: 9,509

Re: [Solved] TV connected with HDMI with wrong dimension

Check the later posts in https://bbs.archlinux.org/viewtopic.php?id=269711 .
Combining what I and Seth posted should give a reasonable explanation .


Disliking systemd intensely, but not satisfied with alternatives so focusing on taming systemd.
Did you use the guided installer ? If yes, I can't help you.

(A works at time B)  && (time C > time B ) ≠  (A works at time C)

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#4 2021-10-05 13:48:38

Xwang
Member
Registered: 2012-05-14
Posts: 323

Re: [Solved] TV connected with HDMI with wrong dimension

Lone_Wolf wrote:

Check the later posts in https://bbs.archlinux.org/viewtopic.php?id=269711 .
Combining what I and Seth posted should give a reasonable explanation .

Thank you.
I've solved the issue when using the laptop alone by setting the correct dpi to 128 and then reducing font size accordngly.
However I still have the issue when I connect the tv.
When I connect it I use the iterate monitor script taken from the Arch's wiki page about Xorg so that to turn off the laptop screen and use the tv as the only monitor (I've only forced the mode to 1920x1080 because otherwise the Tv uses a lower resolution even though it supports the 1920x1080):

#!/bin/bash

# get info from xrandr
connectedOutputs=$(xrandr | grep " connected" | sed -e "s/\([A-Z0-9]\+\) connected.*/\1/")
activeOutput=$(xrandr | grep -E " connected (primary )?[1-9]+" | sed -e "s/\([A-Z0-9]\+\) connected.*/\1/")

# initialize variables
execute="xrandr "
default="xrandr "
i=1
switch=0

for display in $connectedOutputs
do
        # build default configuration
        if [ $i -eq 1 ]
        then
                default=$default"--output $display --auto --mode 1920x1080 "
        else
                default=$default"--output $display --off "
        fi

        # build "switching" configuration
        if [ $switch -eq 1 ]
        then
                execute=$execute"--output $display --auto --mode 1920x1080 "
                switch=0
        else
                execute=$execute"--output $display --off "
        fi

        # check whether the next output should be switched on
        if [ $display = $activeOutput ]
        then
                switch=1
        fi

        i=$(( $i + 1 ))
done

# check if the default setup needs to be executed then run it
echo "Resulting Configuration:"
if [ -z "$(echo $execute | grep "auto")" ]
then
        echo "Command: $default"
        `$default`
else
        echo "Command: $execute"
        `$execute`
fi
echo -e "\n$(xrandr)"

Once I run it the two dimension of xpdyinfo and xrandr differ and moreover the xrandr one is wrong (the real dimension measured with a ruler are 705x395 millimiters).


xdpyinfo | grep -i dimens
  dimensions:    1920x1080 pixels (378x212 millimeters)
xrandr -q
Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 16384 x 16384
eDP-1-1 connected primary (normal left inverted right x axis y axis)
   1920x1080     60.02 +  60.01    59.97    59.96    59.93  
   1680x1050     59.95    59.88  
   1400x1050     59.98  
   1600x900      59.99    59.94    59.95    59.82  
   1280x1024     60.02  
   1400x900      59.96    59.88  
   1280x960      60.00  
   1440x810      60.00    59.97  
   1368x768      59.88    59.85  
   1280x800      59.99    59.97    59.81    59.91  
   1280x720      60.00    59.99    59.86    59.74  
   1024x768      60.04    60.00  
   960x720       60.00  
   928x696       60.05  
   896x672       60.01  
   1024x576      59.95    59.96    59.90    59.82  
   960x600       59.93    60.00  
   960x540       59.96    59.99    59.63    59.82  
   800x600       60.00    60.32    56.25  
   840x525       60.01    59.88  
   864x486       59.92    59.57  
   700x525       59.98  
   800x450       59.95    59.82  
   640x512       60.02  
   700x450       59.96    59.88  
   640x480       60.00    59.94  
   720x405       59.51    58.99  
   684x384       59.88    59.85  
   640x400       59.88    59.98  
   640x360       59.86    59.83    59.84    59.32  
   512x384       60.00  
   512x288       60.00    59.92  
   480x270       59.63    59.82  
   400x300       60.32    56.34  
   432x243       59.92    59.57  
   320x240       60.05  
   360x202       59.51    59.13  
   320x180       59.84    59.32  
DP-1-1 disconnected (normal left inverted right x axis y axis)
HDMI-1-1 disconnected (normal left inverted right x axis y axis)
HDMI-1-2 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 640mm x 360mm
   1360x768      59.80 +
   1920x1080     60.00*   50.00    59.94    30.00    25.00    24.00    29.97    23.98  
   1920x1080i    60.00    50.00    59.94  
   1280x720      60.00    50.00    59.94  
   1024x768      60.00  
   800x600       60.32  
   720x576       50.00  
   720x576i      50.00  
   720x480       60.00    59.94  
   720x480i      60.00    59.94  
   640x480       60.00    59.94  

If there is a way to identify at the end of the iterate monitor script that the connected device is the TV, I could fix its physical size by adding this lines:

for i in 1 2;do
xrandr --fbmm 705x395
done 

or there is a better way to do the same?


I'm still learning English so please excuse me if my English is not good enough and feel free to correct me via PM if you want.

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#5 2021-10-05 20:31:51

seth
Member
Registered: 2012-09-03
Posts: 24,049

Re: [Solved] TV connected with HDMI with wrong dimension

the real dimension measured with a ruler are 705x395 millimiters

W/ or w/o the bezel?

Also it would only be off by 10%

the Tv uses a lower resolution even though it supports the 1920x1080

Its EDID announces 1360x768 as default

Also it's ~77 DPI at 1920x1080 and 55 DPI at 1360x768 - the 96 DPI are probably set by your session (iirc gnome does that) - is this an nvidia system?

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#6 2021-10-06 06:24:42

Xwang
Member
Registered: 2012-05-14
Posts: 323

Re: [Solved] TV connected with HDMI with wrong dimension

seth wrote:

the real dimension measured with a ruler are 705x395 millimiters

W/ or w/o the bezel?

w/o bezel

Also it would only be off by 10%

the Tv uses a lower resolution even though it supports the 1920x1080

Its EDID announces 1360x768 as default



Also it's ~77 DPI at 1920x1080 and 55 DPI at 1360x768 - the 96 DPI are probably set by your session (iirc gnome does that) - is this an nvidia system?

My system is a laptop with nvidia optimus with KDE.
Now I've set sddm to start X with 128 dpi (being that the correct value of the laptop screen).

When I switch to that TV I would like to have the correct size and dpi for that display because otherwise part of the desktop (about 10 to 20 pixel for each side) is not displayed as if the pc "thinks" the display to be a little bigger. The result is that it is extremely difficult to semi blindly operate the bottom panel and to click the three buttons in maximized windows.


I'm still learning English so please excuse me if my English is not good enough and feel free to correct me via PM if you want.

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#7 2021-10-06 07:06:38

seth
Member
Registered: 2012-09-03
Posts: 24,049

Re: [Solved] TV connected with HDMI with wrong dimension

because otherwise part of the desktop (about 10 to 20 pixel for each side) is not displayed

That's probably not related to the resolution and certainly not the DPI but https://en.wikipedia.org/wiki/Overscan - disable that in the Tv ("just scan" setting?)

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#8 2021-10-06 07:14:10

Xwang
Member
Registered: 2012-05-14
Posts: 323

Re: [Solved] TV connected with HDMI with wrong dimension

seth wrote:

because otherwise part of the desktop (about 10 to 20 pixel for each side) is not displayed

That's probably not related to the resolution and certainly not the DPI but https://en.wikipedia.org/wiki/Overscan - disable that in the Tv ("just scan" setting?)

You are right! Thank you very much! Doing so that problem has been solved!!!
So I've reverted back to forcing 96 dpi on my laptop screen too (it works better with thunderbird and firefox and I'm using that setting since 2016), but for the TV a smaller value would be better. Is there a way to understand in the bash if the device connected to hdmi is that TV so that the script can automatically change the dpi when it switches to the TV?

Last edited by Xwang (2021-10-06 07:30:11)


I'm still learning English so please excuse me if my English is not good enough and feel free to correct me via PM if you want.

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#9 2021-10-06 07:30:18

seth
Member
Registered: 2012-09-03
Posts: 24,049

Re: [Solved] TV connected with HDMI with wrong dimension

Please always remember to mark resolved threads by editing your initial posts subject - so others will know that there's no task left, but maybe a solution to find.
Thanks.

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