Adjust your external monitors' built-in controls from the OSX shell:

• brightness
• contrast

And possibly (if your monitor firmware is well implemented):

• input source
• built-in speaker volume
• on/off/standby
• rgb colors
• color presets
• reset

This is a GPLv3 open source repo and you may use it in the ways that license allows.

It is not a Community "Free Software" Project - its decidedly my personal utility and its in the (dreaded/loved) "maintenance mode".

To be blunt, if you have issues with your macOS, Macintosh (not hackintosh), and DDC-controlled monitor(s), then its up to you to debug them and (optionally) PR your fixes (see bottom section) if you'd like to share them.

I don't have the time currently to triage new Issues and help with the non-bugs being reported, and don't intend to moderate a support or discussion forum here.

Open a terminal window and run $ brew install ddcctl.

Head to Releases and from the latest release download ddcctl_binaries.zip archive

• install Xcode
• run make

Run ddcctl -h for some options.
ddcctl.sh is a script I use to control two PC monitors plugged into my Mac Mini.
You can point Alfred, ControlPlane, or Karabiner at it to quickly switch presets.

When setting input source, refer to the table below to determine which value to use.
For example, to set your first display to HDMI: ddcctl -d 1 -i 17.

ddcctl.m sprang from a forum thread on the TonyMac-x86 boards.

DDC.c originated from jontaylor/DDC-CI-Tools-for-OS-X, but was reworked by others on the forums.

A few forks have also backported patches, which is nice 👌.

bug-fix & non-bug-fix/feature PRs have the same broad guidelines:

• well described as to the universal utility of the change for the (presumed) majority of users / developers
  • also helpful: a positive proof that the change doesn't detract from the usability for the majority of users
• easy to test
  • provide your test procedure, if you have one!
  • keep in mind my verification is always manual - I don't have a CI system wired up to a bank of real Macs & monitors

As to additional criteria for new-features, please understand that ddcctl currently does what I need it to do on my own all-Apple fleet.

There is a backlog of some (broadly desirable) features that came from reported issues. PRs are encouraged to address these!

I'm not really interested in adding any features that I have no ability or desire to support on my own hardware.

Unfortunately, I cannot make a time-to-review estimation - but the simpler/cleaner a PR is, the the faster its likely to get reviewed & merged.