Combine multiple Capture Inputs to one Asset

Last updated 7 August 2026

Combine several capture card inputs — or any other assets — into a single asset. From there you can drive one large output, or split the combined image across several smaller ones.

Signals being combined must run pixel synchronous to each other, so genlock them properly. Without that, an image dragged across the boundary between two inputs shows a visible offset.

Before you start

  • A supported capture card installed, with the signals connected and genlocked.

  • Optionally a scene and a sequence to play the result in — the combined image is then visible live as you build it, which is much easier than working blind.

Steps

1. Add a capture input asset per signal

  1. Open the Assets window.

  2. Expand Capture Input and click + to add an asset, then select the new asset.

  3. In the asset properties, expand Capture Input and set:

    • the physical input to use

    • the input bit depth

    • the audio sample rate, if the card carries audio — usually 48000

  4. Expand Properties and check that Opacity is 1. Tick the stereo or transparency options here only if the incoming signal actually carries them.

  5. Repeat for every input you want to combine.

2. Add a Crop & Combine asset

  1. Expand Crop & Combine and click +, then select the new asset.

  2. Expand Crop & Combine in the properties and rename it so it is easy to identify.

  3. Tick Custom Resolution and enter the resolution the combined asset should have. Left unticked, the resolution is derived from the sources instead.

  4. Click Add Asset and pick your capture input assets.

3. Place and size each source

  1. Expand the assets you added.

  2. Set the position mode to Pixel Values and the origin to TopLeft Origin, so coordinates read as pixels from the top-left corner.

  3. Set the size each source should occupy in the combined image.

  4. Position it with the position parameters. Ctrl and click a field to type an exact value.

With a custom resolution set, a source can be moved partly outside the combined asset — whatever falls outside is cropped away. That is the "crop" half of Crop & Combine.

Common Mistakes

  • A moving image tears or steps at the seam between two inputs — the sources are not genlocked. No amount of positioning fixes this; it has to be solved at the signal level.

  • Sources sit centred on top of each other instead of side by side — the origin is still centre-based. Switch to TopLeft Origin before entering coordinates.

  • The combined asset changes size when a source changes — Custom Resolution is unticked, so the resolution follows the sources. Tick it to pin the canvas.

  • One source is invisible — its Opacity is not 1, or transparency was enabled on a signal that carries no alpha.

Tips

  • Play the Crop & Combine asset in a sequence while you build it. Positioning by numbers alone is slow, and the live result makes an off-by-one row obvious.

  • The inputs do not all have to be capture cards — any asset can be a source, so a still or a video can be combined with live signals.

Supported Third Party Hardware — the cards Backstage supports

Capture and Re-map a Video Stream — capturing a stream and re-mapping it to outputs