Blackmagic Design Atem network protocol implementation in swift 5.1 using NIO 2

What's New

Use standardised random function


Swift 5.1 Platforms: macOS & Linux

Atem network protocol implementation

Implementation of BlackMagicDesign's ATEM communication protocol in Swift. It is written on top of Apple's networking library NIO and implements both sides of the protocol: the control panel and the switcher side. This means that you can not only use it to control atem switchers but also to connect to your control panels without the need for a switcher. Opening a whole new world of applications for the Atem control panels. An example can be found at Atem-Simulator

Starting from version 1.0.0 this package uses Swift 5 and NIO2.

Tested platforms

  • macOS 10.14.6 on a MacBook Pro retina 15" late 2013
  • macOS 10.15.3 on a MacBook Pro retina 15" late 2013
  • Raspbian GNU/Linux 9 stretch on a Raspberry Pi model 3 B
  • Raspbian GNU/Linux 10 Buster on a Raspberry Pi 4 model B Rev 1.2


When starting a new project: create a Swift package via SPM

# Shell
> swift package init # --type empty|library|executable|system-module

Then add this library to the package description's dependencies

.package(url: "", from: "1.0.0")

And resolve this new dependency

# Shell
> swift package resolve

Finally import the Atem module in your code

import Atem

You are now ready to create atem controllers and switchers 😎 !


After looking at the following examples, study the API reference for more details.


This example shows how to create a controller that connects to a swicther at ip address and print a message whenever the preview bus changes.

try Controller(ipAddress: "") { connection in
  connection.when{ (change: PreviewBusChanged) in
    print(change) // prints: 'Preview bus changed to input(x)'

Sending messages

To send a message to the switcher use the send(...) method like this:

controller.send(message: ChangeTransitionPosition(to: 5000))


The following example shows how to emulate the basic functionality of an atem switcher. It will forward incoming messages containing transition and preview & program bus changes to all connected controllers.

This snippet is also included in a seperate SPM target "Simulator" (./Sources/Simulator) and can be run by simply executing swift run Simulator in the terminal.

let switcher = Switcher { controllers in
  controllers.when { (change: ChangePreviewBus, _) in
        to: change.previewBus,
        mixEffect: change.mixEffect
  controllers.when{ (change: ChangeProgramBus, _) in
        to: change.programBus,
        mixEffect: change.mixEffect
  controllers.when { (change: ChangeTransitionPosition, _) in
        to: change.position,
        remainingFrames: 250 - UInt8(change.position/40),
        mixEffect: change.mixEffect
  controllers.when { (change: ChangeAuxiliaryOutput, _) in
        source: change.source,
        output: change.output


  • Swift Tools 5.1.0
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Last updated: Tue Nov 08 2022 08:14:38 GMT-0500 (GMT-05:00)