General Purpose Outputs (GPIO)

Overview

Cue Pro can send MIDI messages to external hardware in response to key recording events — rehearsals starting and stopping, the playhead crossing a cue's In or Out Point, record passes beginning and ending, and so on. These messages act as General Purpose Outputs (GPIO), allowing third-party devices on the MIDI network to react to what is happening in the session in real time.

Common uses include driving record safe lights (tally lights outside the recording booth that indicate when a take is in progress), cue lights that signal talent to begin performing, and any other external automation that needs to follow the recording workflow. Because the messages are standard MIDI note-on and note-off commands, they can be picked up by any hardware or software that accepts MIDI input — lighting controllers, broadcast automation systems, custom microcontroller rigs and similar devices.

GPIO is output only — Cue Pro sends messages but does not receive any response from the external device.

MIDI Routing

The GPIO messages are sent on the same MIDI output used for MIDI Triggers. To route them to an external device, ensure that the device is connected to the MIDI output assigned in the TRIGGER tab of Preferences / Settings. Any MIDI interface recognised by macOS can be used.

Command Reference

The table below lists every GPIO message that Cue Pro sends. Each message is a standard three-byte MIDI note-on or note-off command in hexadecimal notation: the first byte is the status (0x90 for note on, 0x80 for note off), the second byte is the note number, and the third byte is the velocity (always 0x01).

Each pair of messages follows a consistent pattern: a note-on message is sent when the action begins, and the corresponding note-off message (same note number) is sent when it ends. This makes it straightforward to map a pair to a relay, light or other on/off device — turn on when the note-on arrives, turn off when the note-off arrives.