My laptop's display has native resolution of 1366x768, and I connect it to my TV which has 1920x1080i. My problem is that the only supported resolution for cloning is 640x480, which happens to be the only resolution that is supported by both the TV and the laptop's display.

But on Windows, I've noticed that cloning works without changing the laptop's display resolution, even when the TV doesn't support the same resolution. Instead of trying to set the TV on the same resolution as the laptop's primary display, they somehow scale each frame (using software scaling or more likely the GPU) to the TV's native resolution.

Is it possible to do that in Linux? I noticed that there is a --scale-from option in xrandr, and it looks like it does just that, but how do I use it? What would the command look like?

  • --scale-from wxh Specifies the size in pixels of the area of the framebuffer to be displayed on this output. This option is actually a shortcut version of the --transform option. See mankier.com/1/xrandr for the man page. – user86969 Jan 9 '15 at 19:29
  • What is your GPU? What drivers do you use? Have you looked at the possibility of compiling custom edids? – mikeserv Jan 12 '15 at 6:41

Finally I made it work using this line:

xrandr --output HDMI1 --off
xrandr --output HDMI1 --auto --scale-from 1366x768

Note that --auto is needed, though I don't know why.

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