The process of assigning a physical control on a MIDI device to a specific function inside DJ software.
MIDI mapping is the configuration layer that tells DJ software which software function to trigger when a specific MIDI message arrives from a controller: for example, assigning a particular knob's CC number to the high-frequency EQ band on channel one. Without a mapping, the software receives the raw MIDI data but does not know what to do with it.
Why it matters
Mapping gives DJs direct control over the layout and feel of their software, and it is the mechanism by which generic controllers become usable for DJing. It is also how purpose-built DJ controllers are configured from the factory: the manufacturer ships a default mapping file that the software loads on first connection.
In practice
Most DJ software offers a MIDI learn function: enter learn mode, click the on-screen control you want to assign, then move the physical knob or press the physical button. The software reads the incoming MIDI message and saves the assignment automatically, removing the need to enter CC numbers manually.
