Fixing HDMI overscan at 1920x1080 on a Seiki 22" TV SE22HY01

So I thought I'd try to see if ddc/ci would work on a seiki 22" TV SE22HY01 but it doesn't support DDC/CI. *sniff*

But I encountered another problem: on the HDMI input, I would get overscanned video so the edges of the ubuntu screen were chopped off.

On this webpage, there was a tip that you could pass xrandr a transformation matrix to resize the screen.


https://newagesoldier.com/linux-hdmi-resize-screen-overscan-fix-ubuntu/


xrandr --output HDMI1 --transform 1.05,0,-35,0,1.05,-19,0,0,1

and I tried that but it seemed to do bilinear filtering, and bilinear filtering of text is absolutely terrible.

So I tried to do a custom resolution with xrandr: (note that I asked for 1900 pixels wide but it rounded it to 1904)

cvt 1900 900
xrandr --newmode "1904x900_60.00" 140.50 1904 2016 2208 2512 900 903 913 934 -hsync +vsync
xrandr --addmode HDMI1 "1904x900_60.00"

and then going to the ubuntu control panel and selecting my new custom resolution and voila! I can see the edges of the screen properly.

if I run xrandr you can see my custom resolution there:

xrandr
Screen 0: minimum 8 x 8, current 1904 x 900, maximum 32767 x 32767
DP1 disconnected (normal left inverted right x axis y axis)
HDMI1 connected primary 1904x900+0+0 (normal left inverted right x axis y axis) 476mm x 268mm
1920x1080 60.00 + 60.00 50.00 59.94 30.00 25.00 24.00 29.97 23.98
1920x1080i 60.00 60.00 50.00 59.94
1904x900 59.88*
1280x1024 60.02
1280x720 60.61 60.00 50.00 59.94
1024x768 75.08 70.07 60.00
800x600 72.19 75.00 60.32
720x576 50.00
720x576i 50.00
720x480 60.00 59.94
720x480i 60.00 59.94
640x480 75.00 72.81 60.00 59.94
720x400 70.08
1904x900_60.00 59.88
VGA1 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)

I could probably try to fiddle with the resolution a bit to get it bigger but this worked the first time so I'm happy enough.



sudo get-edid | parse-edid
This is read-edid version 3.0.2. Prepare for some fun.
Attempting to use i2c interface

Section "Monitor"
Identifier "SE22HY01"
ModelName "SE22HY01"
VendorName "SEK"
# Monitor Manufactured week 50 of 2012
# EDID version 1.3
# Digital Display
DisplaySize 480 270
Gamma 2.20
Option "DPMS" "false"
Horizsync 30-80
VertRefresh 47-63
...
EndSection


=======================


Hmmm. I think I can get a little better resolution that's the same aspect ratio, let's try 98 percent:

so from a bash command prompt let's do a little math with the double parenthesis thing:

echo $((1920*98))
188160
echo $((1080*98))
105840

so multiplying by 98 gives me the percent multiply if I drop the last two digits of the result: 1882x1058

cvt 1882 1058
xrandr --newmode "1888x1058_60.00" 166.25 1888 2008 2208 2528 1058 1061 1071 1098 -hsync +vsync
xrandr --addmode HDMI1 "1888x1058_60.00"


It seems if I choose 1920x1080 the TV wants to do overscan, but any other resolution it will fill the screen as I would expect.

Hmmmm. so why not try just a little different resolution that's close to 1920x1080 like say 1910x1080

cvt 1910 1080
xrandr --newmode "1912x1080_60.00" 171.25 1912 2032 2232 2552 1080 1083 1093 1120 -hsync +vsync
xrandr --addmode HDMI1 "1912x1080_60.00"

and yes, no pesky overscan and practically full HD resolution, minus 8 pixels.

Hmmmmm. why not try full horiz resolution but take away one horizontal line for 1920x1079.

cvt 1920 1079
xrandr --newmode "1920x1079_60.00" 172.75 1920 2048 2248 2576 1079 1082 1092 1119 -hsync +vsync
xrandr --addmode HDMI1 "1920x1079_60.00"

Beauty. No overscan and I only lose one line of resolution.

I still can't understand why you would want overscan when you have a perfect 1920x1080 signal that would fill the screen.

If I pump a 1920x1080 signal into the VGA input of the TV it displays without overscan, so why would it do that on the HDMI?


The other annoying thing is that it won't go into a power save mode on the HDMI input. Instead of doing the energy star power save, it displays the message "Not Support".

If I want to put it into power save, I have to put the computer into standby and after a bit it will turn itself off. I have to manually turn the TV back on after the computer has resumed from standby.