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How can I change the HDMI resolution of my running Raspbian (Jessie) system without rebooting my Raspberry Pi 3?

Frank Breitling
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3 Answers3

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You can sort of. But it is not working really well. At least in the command line you can turn off the HDMI port and get it back on with a different resolution. So you are good for Raspbian Lite.

Here is what you have to do:

tvservice --off                  ; turn off tv service
tvservice -e "DMT 68 DVI"        ; set it on (you will see a black screen)
sudo chvt 2                      ; change to different virtual terminal
sudo chvt 1                      ; change back to the previous virtual terminal
fbset -g 1920 1200 1920 1200 32  ; adjust the size of the framebuffer

(Adapt the values as needed.)

This also works for OpenGL applications but it does not with a desktop environment. There is something different missing after powering on the HDMI port to get xserver back instead of chvt.

I think Unix StackExchange is a better place to ask about that.

kwasmich
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You can use the "tvservice" command for this. For example

tvservice --explicit="DMT 35 HDMI"

This powers on HDMI explicitly with "DMT mode 35" which is 60 HZ at 1280x1024 pixels.

There is also tvservice --off if you've want to turn the output off completely.

For more information try both

tvservice --help and looking here for a tabular listing of modes.

flakeshake
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You cant. You have to set it in the /boot/config.txt which is used for the boot config. Once you change the default there - it will use the resolution you specified on boot. Each time you change it will require a reboot.

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    I thought you were looking for a Windows or Mac type solution.

    Use 'tvservice -d edid' and 'edidparser edid' in the commandline to pull a list of display modes supported by your connected monitor.

    tvservice -m CEA and tvservice -m DMT will list ALL display modes supported by PI. This is only partially helpful as it does not denote which your display supports.

    Once you identify your supported display mode(s) - you can update them using the command line. These changes are not permanent - the moment you reboot it will default. To set permanently you will need to update the boot config.

     –  Mar 27 '17 at 22:20
  • If the screen goes black or appears distorted then it is likely the result of trying to enable a video mode not supported by your monitor. If you run the commands that I provided, it should output the modes your monitor supports. Make sure that you are implementing one of the listed options that are returned. –  Mar 28 '17 at 15:58
  • That's exactly what I did and these resolutions work when I set them in /boot/config.txt. – Frank Breitling Mar 28 '17 at 16:17
  • I have no problem finding the supported solution and executing those commands. However the resolution does not change properly. The screen goes black sometimes or looks messed up so that I have to reboot. I am looking for the commands to change e.g. from 1920x1080 to 800x600 and back. – Frank Breitling Mar 27 '17 at 23:15