ddcutil and ddcui

Announcements

02 February 2022

ddcui release 0.2.1 better handles DDC communication failures resulting from conflict with other programs. Like dddcutil 1.2.2, ddcui command line option -force-slave-address allows ddcui to override the other program's claim to the display.

For a detailed description of ddcui changes and bug fixes in this release, see ddcui Release Notes.

Prebuilt packages for several Linux distributions and mmachine architectures can be found in the ususal locations.

28 January 2022

ddcutil release 1.2.2 contains one set of changes of interest to general users:

  • Handling of DDC communication failures due to conflict with other programs is improved. In particular, conflict occurs when device driver ddcci is loaded. Among the changes:
  • If ddcutil detect fails to communicate with a monitor and Linux errno EBUSY is reported, it reports the monitor as "Busy" instead of "Invalid" and suggests the use of option --force-slave-address.
  • Messages regarding EBUSY errors are always written to the system log.
  • API functions ddca_enable_force_slave_address() and ddca_is_force_slave_address_enabled() have been added.

For a detailed description of ddcutil changes and bug fixes, see Release Notes.

Prebuilt packages for several Linux distributions and mmachine architectures can be found in the ususal locations.

Prior announcements can be found here.

Introduction

ddcutil is a Linux program for managing monitor settings, such as brightness, color levels, and input source. Generally speaking, any setting that can be changed by pressing buttons on the monitor can be modified by ddcutil.

ddcutil primarily uses DDC/CI (Display Data Channel Command Interface) to communicate with monitors implementing MCCS (Monitor Control Command Set) over I2C. Normally, the video driver for the monitor exposes the I2C channel as devices named /dev/i2c-n. Alternatively, there is support for monitors (such as Eizo ColorEdge displays) that implement MCCS using a USB connection. See USB Connected Monitors.

A particular use case for ddcutil, and the one that inspired its development, is as part of color profile management. Monitor calibration is relative to the monitor color settings currently in effect, e.g. red gain. ddcutil allows color related settings to be saved at the time a monitor is calibrated, and then restored when the calibration is applied.

Restrictions:

  • ddcutil does not support laptop displays, which are controlled using a special API, not I2C.
  • Generally speaking, ddcutil can be built in a virtual machine, but will not run in a VM. This is because the virtual video drivers do not implement I2C. However, if the VM is connected to a separate video card and is running a non-virtualized driver for the card in passthru mode, then ddcutil will work.
  • Nvidia's proprietary video driver may require special configuration. See Special Nvidia Driver Settings.
  • Reading and writing Table type features is implemented but untested. See Table Features

ddcutil is released under the GNU Public License, V2 (GPLV2). The source is hosted on Github.

General support questions are best directed to the issue tracker on Github. Use of that forum allows everyone to benefit from individual questions and ideas. For details, see Technical Support.

ddcui

ddcui is a graphical user interface to ddcutil, built using Qt. It is currently beta level code. For further information, see ddcui Overview.

ddcui is released under the GNU Public License, V2 (GPLV2). The source is hosted on Github.

ddcui questions should also be directed the to the ddcutil issue tracker on Github.

Topics

Using ddcutil:

Commands and Options:

Installation and Configuration:

Other:

Author

Sanford Rockowitz rockowitz@minsoft.com