External Control Overview

WATCHOUT can be controlled by a wide range of external devices and systems — lighting consoles, show controllers, tracking systems, MIDI devices, timecode generators, and custom software. This chapter covers the external control architecture, the protocols WATCHOUT supports, and how they all connect to the show through a unified variable system.

Control Architecture

External control in WATCHOUT follows a layered architecture. Signals from the outside world are received, converted into variable updates, then distributed to all rendering nodes in real time.

The node that runs the Director listens for most external protocols. It receives incoming Art-Net, OSC, PosiStageNet, HTTP, and WATCHOUT 6 protocol messages. Each message is converted into a standardized internal format and passed to the Director.

The Director is the authoritative coordinator. It validates incoming values against the variable definitions in the show. It then broadcasts the updated state to all connected Runners. Runners apply the new values to their rendering pipeline in real time.

The MIDI Bridge and LTC Bridge are standalone services. Each has its own connection to the Director. MIDI handles variable input and show control. LTC handles timeline synchronization.

Everything Maps to Variables

All external control maps to WATCHOUT variables. An incoming signal is matched to a variable by its key, clamped to the variable's range, then made available throughout the show. Every protocol writes to the same pool of variables — you choose a protocol to fit your production environment, not to reach a different feature set.

For variable properties, key formats, and how inputs reach the show, see Variables and Inputs.

Supported Protocols

WATCHOUT supports the following external control protocols:

  • Art-Net — DMX-over-IP for lighting console integration. Maps DMX channel values to variables.
  • OSC — Open Sound Control for media servers and show controllers. Handles variable input and timeline playback.
  • HTTP REST API — Control via standard HTTP requests. Covers playback, variable input, show management, hit testing, and event streams.
  • MIDI Bridge — Standalone service. Receives MIDI Control Change, Note, and Pitch Wheel messages as variable updates.
  • LTC Bridge — Standalone service. Decodes Linear Time Code from an audio input to synchronize timeline playback.
  • PosiStageNet (PSN) — Receives 3D position data from tracking systems and maps it to variables.
  • MIDI Show Control (MSC) — Show-equipment control protocol. Supports GO, STOP, GO OFF, and RESET commands.
  • WATCHOUT 6 Protocol — Backward-compatible control interface over TCP and UDP. Accepts commands in the WATCHOUT 6 format.

Enabling and Disabling Protocols

Enable or disable each protocol from the Nodes window, in Node Info → Protocols. The section provides these toggles:

  • Art-Net — Art-Net listener.
  • OSC — OSC listener.
  • PosiStageNet — PSN receiver.
  • Web UI — Browser control interface served by the Asset Manager.
  • WATCHOUT 7 protocol — HTTP REST API endpoints and the built-in API documentation interface.
  • WATCHOUT 6 protocol — Backward-compatible interface over TCP and UDP.

The MIDI Bridge and LTC Bridge are not toggles. The Nodes window has MIDI Bridge and LTC Bridge buttons that open a configuration dialog for each.

Disable protocols you are not using to reduce network traffic and minimize the system's attack surface on public or shared networks.

Input Interpolation

To prevent visual glitches from sudden value changes, external inputs pass through an interpolation window. When a new value arrives, renderers transition from the old value to the new value over the window rather than jumping instantly.

The default window is 50 ms. This interpolation applies to all protocols:

  • Art-Net and OSC add the interpolation timestamp before forwarding to the Director.
  • MIDI and other bridge services rely on the Director to apply the default 50 ms interpolation.
  • HTTP REST API supports an optional duration parameter for a custom time, from instant (0 ms) to multi-second fades.

The 50 ms default gives smooth transitions without noticeable latency. It suits real-time control such as fader movements and tracking data.

Choosing a Protocol

The best protocol depends on your production environment:

  • Lighting desk integration → Art-Net. Lighting consoles speak DMX/Art-Net natively. This is the most natural choice for controlling WATCHOUT from a lighting desk.
  • Show controller or media server → OSC or HTTP REST API. OSC suits show controllers and tablet-based control surfaces. HTTP suits custom software, web-based control panels, and scripted automation.
  • External timecode synchronization → LTC Bridge. When WATCHOUT playback must lock to an external SMPTE timecode source (audio/video playback, broadcast, multi-system sync), the LTC Bridge synchronizes timeline playback to the incoming timecode.
  • Position tracking → PosiStageNet. For content that follows performers or objects on stage, PSN receives real-time position data from tracking systems.
  • Existing WATCHOUT 6 integration → WATCHOUT 6 Protocol. A control system programmed for WATCHOUT 6 works without changes through the backward-compatible protocol.
  • Manual fader control → MIDI Bridge. Physical MIDI controllers with faders and knobs provide tactile, hands-on control of WATCHOUT variables.
  • Theatrical cue triggering → MIDI Show Control. MSC is the industry standard for triggering cues across multiple show control devices in theater and live event environments.
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