Use a videosplitter with Backstage (f.e. FX4)

Last updated 7 August 2026

A video splitter takes one high-resolution output and splits it into several smaller ones — a UHD signal becoming four HD outputs, for example. Backstage drives this by splitting the GPU output into regions and routing each region to its own display or projector.

Before you start

The splitter connected to a GPU output of the server.
An Emulate EDID with nVidia GPUs for the resolution the GPU has to output — typically 3840×2160 for four HD outputs.
The splitter itself configured for the same layout. For the Datapath FX4 there is a walkthrough video.

Most splitters have four outputs. If you only need three, still configure a 2×2 split and leave one output unused — the split geometry has to match on both sides.

Steps

1. Select the GPU output

Open Backstage, either locally or through the remote UI in the Brainsalt Hub Desktop App.
Open the Outputs window.
Select the output the splitter is connected to, under GPU Output.

If the output does not appear even though the EDID is emulated, restart Backstage — GPU outputs are enumerated at startup.

2. Split the output

Expand the Split section.
Set Type to Matrix Split for a regular grid — this is the case a splitter needs.
Enter Columns and Rows to match the splitter's configuration. UHD into four HD outputs is 2 columns × 2 rows.
Click Create Split.

Each region now appears as its own output, so everything downstream treats it like a separate physical output.

Custom instead of Matrix Split defines regions by name, pixel offset and size — for a splitter whose regions are not a regular grid, or when only part of the output is used.

3. Route the regions

In an existing scene, use Video Routing Window to route each split region to its own display or projector.
Starting from scratch, Get Started with Backstage first, then route.

Each region can be warped independently afterwards, so a projector fed by one quadrant is aligned exactly as it would be on a dedicated output.

Common Mistakes

The split in Backstage does not match the splitter — both sides have to agree. A 2×2 split feeding a splitter configured for 1×4 produces four outputs showing the wrong quarters.
The GPU output is missing after emulating the EDID — outputs are enumerated at startup. Restart Backstage.
The output resolution does not match the EDID — the split divides whatever the GPU actually outputs. If the emulated mode is not active, every region is the wrong size.

Tips

Give the split regions names that identify the physical projector they end up on. In routing they are otherwise distinguishable only by index.
The regions behave as ordinary outputs, so warping, blending and stereo settings all apply per region.

Get Started with Backstage — full walkthrough from an empty project to content on screen

Output Warping — mesh warping, which applies per split region

GPU Output — GPU output properties, including the split options

Visual Output Default Properties — properties shared by all visual outputs