DDC

DDC stands for Display Data Channel, a family of display communications. The part used to control a monitor is DDC/CI, which adds a command interface. BetterDisplay can use this path to request hardware changes such as brightness, contrast, volume or input selection.

It helps to separate the command from the connection carrying it. The Monitor Control Command Set (MCCS) defines monitor controls using Virtual Control Panel (VCP) codes. A VCP code identifies what to adjust; communication support determines whether the command can reach the device. VESA’s MCCS description

A monitor may implement only some commands, and the connection can affect which ones work. Seeing a configured control in BetterDisplay is therefore not proof that the monitor supports it.

DDC changes a monitor setting. Software brightness changes the rendered image instead. Likewise, the monitor's own on-screen menu is separate from BetterDisplay's OSD, which provides feedback in macOS.

See DDC Control for setup and compatibility settings.