ddc

Display Data Channel utility for Mac OS X
© 2012 Philipp Antoni, infinise.com

Used to read and control display settings via the DDC protocol. Largely based on http://lists.apple.com/archives/accessibility-dev/2011/Feb/msg00000.html and lots of trial and error.

Warning

This tool might seriously crash your whole computer. It's low-level and severly under-tested.

Here's where it's confirmed to fully work:

• OS X 10.7.4, Late 2011 MacBook Pro, Samsung S27A850T via DisplayPort or HDMI

Confirmed to work, but returning wrong information:

• OS X 10.8.2, Early 2011 MacBook Pro, Acer P246H

Confirmed to freeze the whole system:

• OS X 10.8.1, Late 2008 MacBook Pro
• OS X 10.8, 2008 MacBook

If you have any luck with your setup please let me know: http://twitter.com/philippantoni

Usage

Read:
ddc <decimal VCP code>

Write:
ddc <decimal VCP code> <decimal value>

Examples

Get current brightness level
ddc 16

Set brightness level to 75%
ddc 16 75

Increase brightness by 10%
ddc 16 +10

Save settings (required after some changes)
ddc 176 1

Disable display OSD (value 2 to re-enable)
ddc 202 1

What to do with this

The first step would be to check whether your display supports DDC. Run ddc 16 and see if it ouputs anything reasonable.

You could then use FunctionFlip to regain control over the F1 & F2 keys on your keyboard and bind those to the included AppleScripts with an app like Alfred.

Further reading

Learn about DDC on Wikipedia (not very helpful though):
http://en.wikipedia.org/wiki/Display_Data_Channel
http://en.wikipedia.org/wiki/Monitor_Control_Command_Set

Some actual information about how DDC works:
http://www.boichat.ch/nicolas/ddcci/specs.html

This document contains a list of all VCP codes (not guaranteed to work for your monitor):
http://d.pr/f/ea49 (.doc, see page 20)

Two free (but very complex) Windows tools to detect your monitor's capabilities:
http://www.entechtaiwan.com/lib/softmccs.shtm
http://www.portrait.com/enu/dt/toolbox.html