Brightness - ACPI or Xrandr - Which is good?

[Testuser]

Hi Team,

Just one query.

Regarding brightness control.

On Internet I found the difference but not sure.

ACPI - Hardware based brightness control - so power consumption is reduced.

Xrandr - Software based. Might not reduce power consumption.

Please advise with your thoughts.

[Rava]

ACPI - Hardware based brightness control - so power consumption is reduced.

Xrandr - Software based. Might not reduce power consumption.

With the internal notebook's or sub-notebook's display I either use the XFCE system tray slider (but I have no clue what XFCE uses in the background), or a xrandr based script.
At least all external monitors I know and use only the monitor's own brightness control works.

power consumption is reduced.
[…] Might not reduce power consumption.

Would be good to get exact findings on that. Does anyone know an article on the issue?

[Testuser]

Hi Rava,

Here is what I found.

https://wiki.archlinux.org/title/backlight.

For me xbacklight not workiing in Desktop, only working in laptop.

Xrandr - working on both desktops and laptop, So I beleive it is software based brightness control ( not actually reducing the brightness, this increases the blackness on the display - this is what I read in one of the forum in internet, now not able to find that link).

Anyway, I have posted a simple bright changer app for laptops using xbacklight and acpi.

This one uses yad program included in the package.