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ddcci

Paid Linux

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What ddcci is

ddcci is a free, GPL-licensed command-line tool for controlling DDC/CI monitors on Linux. It can query a monitor's EDID at I2C address 0x50 and request its capabilities at address 0x37. A discovery option checks controls numbered 0 through 255, and another option can skip the validity check. Users select a control to read or write, provide a value for a write, and can send a separate command to save adjustments. Listed controls include brightness, contrast, input source, speaker volume, and power. Some Samsung monitors may need a dedicated DDC/CI enable command. The maker cautions that symbolic control names are based on Samsung SyncMaster 173T functionality and may not be correct for other monitors. The Mitsubishi Diamond Pro 2060u is specifically noted as lacking support for capability requests. Source downloads are linked as ZIP and tar.gz files, and the maker says patches are accepted. The README credits Oleg I. Vdovikin as author.

Who it suits

It suits Linux users who want command-line access to monitor controls through DDC/CI, including brightness and input switching.

What it does well

  • Free and GPL-licensed
  • Reads and writes monitor controls
  • Includes input source among listed controls
  • Offers source downloads and accepts patches

What to know first

  • Linux only
  • Symbolic control names may be wrong for other monitors
  • Mitsubishi Diamond Pro 2060u lacks capability requests

Verdict

ddcci provides command-line monitor queries and control changes, with options to discover controls and save adjustments. Check the control-name caveat against your monitor before relying on symbolic names.

Facts from ddcci's own pages

Capabilities query
The -c option queries the monitor's DDC/CI capabilities string. · bhuvanchandradv.github.io, 9 Oct 2026
Compatibility limit
The page says the Mitsubishi Diamond Pro 2060u does not support capabilities requests. · github.com, 9 Oct 2026
Control discovery
The -d option queries controls 0 through 255 and checks their validity, with -f available to override the validity check. · bhuvanchandradv.github.io, 9 Oct 2026
Control names
The page says symbolic control names are based on Samsung SyncMaster 173T functionality and may be incorrect for other monitors. · bhuvanchandradv.github.io, 9 Oct 2026
Controls
It can query available monitor controls and read or write a specified control, including brightness. · bhuvanchandradv.github.io, 9 Oct 2026
EDID query
The -e option queries monitor EDID at I2C address 0x50. · bhuvanchandradv.github.io, 9 Oct 2026
Installation
The maker's page links to ZIP and tar.gz source downloads and to the GitHub repository. · bhuvanchandradv.github.io, 9 Oct 2026
Known limitation
The README says the Mitsubishi Diamond Pro 2060u does not support capability requests. · github.com, 9 Oct 2026
License
The repository README describes the program as GPL-licensed. · github.com, 9 Oct 2026
License and author
The repository README says the program is GPLed and written by Oleg I. Vdovikin. · github.com, 9 Oct 2026
Monitor compatibility
The maker says symbolic control names are based on Samsung SyncMaster 173T functionality and may be incorrect for other monitors. · bhuvanchandradv.github.io, 9 Oct 2026
Monitor controls
The page lists controls including brightness, contrast, input source, speaker volume, and power. · bhuvanchandradv.github.io, 9 Oct 2026
Monitor data
The tool can query monitor EDID at I2C address 0x50 and DDC/CI capabilities at address 0x37. · bhuvanchandradv.github.io, 9 Oct 2026
Purpose
ddcci is a command line interface for controlling DDC/CI monitors. · bhuvanchandradv.github.io, 9 Oct 2026
Read and write controls
The -r option selects a control to read or write, and -w supplies the value to write. · bhuvanchandradv.github.io, 9 Oct 2026
Samsung support
The -S option sends a Samsung DDC/CI enable command, which the page says some Samsung monitors seem to require. · bhuvanchandradv.github.io, 9 Oct 2026
Save settings
The -s option sends a DDC/CI command to save adjustments made with -w. · bhuvanchandradv.github.io, 9 Oct 2026
Support
The maker says they accept patches and directs users to inspect the tool if it hangs or does not work. · bhuvanchandradv.github.io, 9 Oct 2026

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