I can set the display scaling mode for the internal laptop panel with:
xrandr --output LVDS1 --set "scaling mode" "Full aspect"
This however does not work for external displays (DP1, VGA1, DP1) because the scaling mode property is not supported:
$> xrandr --output HDMI1 --set "scaling mode" "Full aspect" X Error of failed request: BadName (named color or font does not exist) Major opcode of failed request: 140 (RANDR) Minor opcode of failed request: 11 (RRQueryOutputProperty) Serial number of failed request: 47 Current serial number in output stream: 47
How can I preserve the aspect ratio when displaying a lower resolution content?