vMix EmberPlus Bridge

June 11, 2026 · View on GitHub

Overview

The vMix EmberPlus Bridge is a Node.js application that acts as a bridge between a vMix instance and EmberPlus clients, such as Lawo's VSM.

It performs the following functions:

  • Monitors vMix Status:

    • Tally Updates: Receives a string like TALLY OK 0121... where each digit represents the tally state for an input (0 = off, 1 = program, 2 = preview).
    • ACTS Updates: Receives individual lines such as:
      • ACTS OK Recording 1
      • ACTS OK MultiCorder 0
      • ACTS OK Streaming 1
        These indicate the statuses for Recording, MultiCorder, and Streaming respectively.

  • Exposes an EmberPlus Provider Tree:
    The tree includes:

    • Studio Subtree:
      • Program Tally (one boolean per input, up to 32 inputs)
      • Preview Tally (one boolean per input, up to 32 inputs)
      • vMix Connected flag (boolean)
      • ACTS Status subtree with nodes for Recording, MultiCorder, and Streaming (boolean)
    • Functions Subtree:
      Contains the following function nodes:
      • Auto Mix 1 (sends FUNCTION CUT)
      • Stinger 1 (sends FUNCTION STINGER1)
      • Stinger 2 (sends FUNCTION STINGER2)
      • Stinger 3 (sends FUNCTION STINGER3)
      • Stinger 4 (sends FUNCTION STINGER4)
      • Transition 1 (sends FUNCTION TRANSITION1)
      • Transition 2 (sends FUNCTION TRANSITION2)
      • Transition 3 (sends FUNCTION TRANSITION3)
      • Transition 4 (sends FUNCTION TRANSITION4)
    • Matrices Subtree:
      Contains the vMix Routing Matrix. Targets are the routable vMix outputs (Output 2, 3, 4); sources are the vMix inputs plus Program, Preview, MultiView 1, and MultiView 2. Routing a source to a target sends the matching FUNCTION SetOutput<n> command to vMix. (Output 1 is Program-locked and the Fullscreen outputs cannot take an input, so they are not exposed as targets. Secondary mixes are not exposed because vMix renders them as black on NDI/external outputs.)

  • Function Invocation:
    When an EmberPlus function is invoked (via an EmberPlus client), the bridge sends the corresponding vMix command (if the TCP connection is active).

  • Robust Connection Handling:
    If the vMix TCP connection fails, the bridge uses a back-off strategy (with delays of 2, 4, 16, then 30 seconds for subsequent attempts) to attempt reconnection. The "vMix Connected" node in the EmberPlus tree reflects the connection status.

Companion viewer: emberviewer

If you need a consumer to inspect, test, or operate this provider, try emberviewer - a cross-platform Ember+ viewer. It connects to this bridge (or any Ember+ provider) and lets you walk the tree, watch tallies flip live, and drive the routing matrix. It is the quickest way to see what this provider emits, and it works with other Ember+ devices too.

Breaking changes in 2.0.0

The Ember+ tree layout changed, so consumers must remap. This was done early in the project's life, while the impact is small, to settle the structure before more deployments rely on it. Two changes affect existing addressing:

  • Flatter tally tree. Each tally input is now a single boolean parameter directly under Program/Preview Tally (path 1.1.1.N), instead of a node wrapping a boolean (old path 1.1.1.N.1). This halves the depth and element count of the tally banks.
  • Flatter ACTS Status. Recording, MultiCorder, and Streaming are now boolean parameters directly under ACTS Status (1.1.4.1 / .2 / .3), instead of a wrapper node per status holding a boolean.
  • Routing matrix only exposes what works. Targets are Output 2-4 (Output 1 is Program-locked, Fullscreen outputs cannot take an input); sources are the inputs plus Program, Preview, MultiView 1, and MultiView 2, with corrected vMix command values. Secondary mixes were tried and dropped (vMix renders them black on those outputs).
  • Matrix labels reworked. Source/target names now live as string parameters keyed by signal id under a Labels container, addressed by an absolute basePath, following the Lawo Ruby / Arkona convention. The previous per-signal Label child parameters and relative basePath did not resolve in standard consumers and have been removed.

Requirements

  • Node.js (v20 or later recommended; the Docker image uses Node 24 LTS)
  • npm (Node Package Manager)

Installation

Docker

docker run -p 9000:9000 -e VMIX_HOST=<your_vmix_host> -e VMIX_PORT=8099 mattlamb99/vmix-emberplus-bridge

Locally

  1. Clone the Repository:

    git clone <repository_url>
cd <repository_directory>

  2. Install Dependencies:

    npm install

This project depends on:
  • emberplus-connection
  • chalk

Configuration

By default, the bridge expects the vMix instance to be available on localhost port 8099. If your vMix instance is running on a different host or port, set ENV variables VMIX_HOST and or VMIX_PORT

const VMIX_HOST = 'localhost';
const VMIX_PORT = 8099;

Usage

Run the bridge with:

node bridge.js

The application will:

  • Start the EmberPlus server on port 9000.
  • Attempt to connect to vMix and subscribe to both TALLY and ACTS updates.
  • Update the EmberPlus tree with live data:
    • Tally Updates for Program and Preview tallies.
    • ACTS Updates for Recording, MultiCorder, and Streaming statuses.
    • vMix Connected status.
  • Listen for function invocations and, if triggered, send the corresponding commands to vMix.

EmberPlus Tree Structure

vMix
 ├─ Studio
 │    ├─ Program Tally
 │    │      └─ Input 1 ... Input 32 (boolean, one parameter per input)
 │    ├─ Preview Tally
 │    │      └─ Input 1 ... Input 32 (boolean, one parameter per input)
 │    ├─ vMix Connected (boolean)
 │    └─ ACTS Status
 │           ├─ Recording (boolean)
 │           ├─ MultiCorder (boolean)
 │           └─ Streaming (boolean)
 ├─ Functions
 │    ├─ Auto Mix 1 (FUNCTION CUT)
 │    ├─ Stinger 1 (FUNCTION STINGER1)
 │    ├─ Stinger 2 (FUNCTION STINGER2)
 │    ├─ Stinger 3 (FUNCTION STINGER3)
 │    ├─ Stinger 4 (FUNCTION STINGER4)
 │    ├─ Transition 1 (FUNCTION TRANSITION1)
 │    ├─ Transition 2 (FUNCTION TRANSITION2)
 │    ├─ Transition 3 (FUNCTION TRANSITION3)
 │    └─ Transition 4 (FUNCTION TRANSITION4)
 └─ Matrices
       └─ Routing
             ├─ vMix Routing Matrix (targets: Output 2-4; sources: Input 1-21,
             │                       Program, Preview, MultiView 1/2)
             └─ Labels
                   ├─ Targets (one string parameter per target, keyed by signal id)
                   └─ Sources (one string parameter per source, keyed by signal id)

The tally inputs are flat boolean parameters: Program Tally -> Input N lives at path 1.1.1.N (not 1.1.1.N.1). The matrix label nodes follow the Lawo Ruby / Arkona convention so consumers such as Lawo VSM and emberviewer resolve the source/target names.

vMix TCP API Subscriptions

TALLY Updates:

Sent using: SUBSCRIBE TALLY

Responses (e.g., TALLY OK 0121...) update the Program and Preview tallies for each input.

ACTS Updates:

Sent using: SUBSCRIBE ACTS

Responses update the corresponding ACTS statuses for:

  • Recording
  • MultiCorder
  • Streaming

Function Commands

The following functions send the corresponding commands to vMix when invoked:

Ember FunctionvMix Command
Auto Mix 1FUNCTION CUT
Stinger 1FUNCTION STINGER1
Stinger 2FUNCTION STINGER2
Stinger 3FUNCTION STINGER3
Stinger 4FUNCTION STINGER4
Transition 1FUNCTION TRANSITION1
Transition 2FUNCTION TRANSITION2
Transition 3FUNCTION TRANSITION3
Transition 4FUNCTION TRANSITION4

Error Handling & Reconnection

If the vMix TCP connection is lost:

  • The vMix Connected node is updated to false.
  • The bridge logs a human-readable error message.
  • A reconnection attempt is scheduled with exponential back-off:
    • 2 seconds, then 4 seconds, then 16 seconds, and finally 30 seconds between attempts.
  • When the connection is re-established, the vMix Connected node is updated to true and the bridge resubscribes to both TALLY and ACTS updates.

License

This project is licensed under the MIT License.

Contributions

Pull requests & help is welcome.

Acknowledgments

vMix TCP API Documentation EmberPlus and the EmberPlus Connection Library. Chalk for colorized logging.