> ## Documentation Index
> Fetch the complete documentation index at: https://docs.fabl.studio/llms.txt
> Use this file to discover all available pages before exploring further.

# ATEM

> Control Blackmagic ATEM video switchers — program and preview inputs, transitions, keyers, fade to black, and record/stream — with live state and triggers.

The **ATEM** device controls Blackmagic Design ATEM video switchers. It's a natural fit for studio mode: cue and take rundown items that cut or transition your switcher's program output automatically.

## Connection

The agent connects to the switcher over the network. Provide the switcher's **host** and, if needed, adjust the **port** and the **mix-effect (ME) index** for multi-ME switchers. The common control port is **9910**.

## Commands

The ATEM device supports the core switcher operations, including:

* Set **program** and **preview** inputs
* Perform a **cut** or **auto transition**
* **Fade to black**
* Control **upstream** and **downstream keyers** (on/off air)
* Start and stop **recording** and **streaming**
* Run switcher **macros** and control **aux** outputs

## State and triggers

The device reports its connection state and raises triggers your [rules](/automation/rules) can react to, including:

* Connection changes
* Program and preview input changes
* Transition activity and fade-to-black changes
* Upstream and downstream keyer on-air changes
* Recording and streaming state changes

Trigger data such as the input number and ME index is available for use in rule actions.