Spout is one of the most useful technologies in a Windows live-visual workflow because it lets compatible applications share video directly through the GPU. Instead of rendering a visual, encoding it, sending it over a network and decoding it again, one application exposes a texture that another compatible application can receive.
- Spout is Windows-focused and ideal for same-computer app-to-app video.
- Use it when another program creates the visuals and HoloMapper only needs to map them—or when HoloMapper output needs to enter OBS/another app.
- Keep all Spout applications on the same GPU where possible.
- Use NDI instead when the video needs to cross a network to another machine.
What is Spout?
Spout is a free, open-source Windows video-sharing system that uses GPU texture sharing for real-time routing between applications. Its official site lists creative tools such as Resolume, Max, Processing, MadMapper and TouchDesigner as examples of applications that can participate in Spout workflows.
For projection mapping, this means the “content app” and the “mapping app” can be different programs without requiring a capture card or network encode/decode step.
Use Spout input in HoloMapper
A common signal flow is:
TouchDesigner / Resolume / OBS / Unity / generative app → Spout → HoloMapper → projector
- Enable Spout output in the source application.
- Name the sender clearly.
- In HoloMapper, add a Spout source.
- Select the sender from the available list.
- Place the live texture on the desired mapping surface.
- Warp and align the surface to the physical object.
This lets the source application concentrate on effects, interaction or composition while HoloMapper maintains the projector geometry.
Send HoloMapper output through Spout
The reverse workflow is also useful:
HoloMapper → Spout → OBS / Resolume / recording tool
You can capture the mapped composition in another application, combine it with overlays, feed it into a broader VJ system, or monitor it without pointing a camera at the projector.
OBS and Spout
OBS Studio can participate in Spout workflows through compatible plugins. That turns OBS into a powerful media hub: browser sources, webcams, capture cards and screen captures are mixed in OBS, then the finished scene is sent to HoloMapper for projection geometry.
See the dedicated OBS projection mapping tutorial for the full signal-flow approach.
The most common Spout problem: different GPUs
Gaming laptops and some desktops can run different applications on different graphics adapters. Because Spout depends on GPU texture sharing, the source and receiver usually behave best when they use the same GPU.
If a sender appears but shows no image—or does not appear at all—check Windows graphics preferences and make sure both applications are assigned to the same high-performance GPU. Also confirm that the source application is actually publishing a sender.
Resolution, alpha and sender naming
Spout does not magically make every source format identical, so decide what resolution and aspect ratio your source application should publish. If the sender is 1920×1080 but the mapped surface is very wide or very tall, you may still need crop, fit or fill adjustments in the receiving application. When a source uses transparency, confirm that both the sender and receiver agree on how alpha is handled; otherwise transparent areas can appear black or show unwanted edges.
Clear sender names also matter once a project grows. Instead of leaving several anonymous outputs, use names such as OBS_Main, TD_Particles or Resolume_Fill. That makes it much easier to reconnect a scene after restarting applications or moving between rehearsal and show files.
Spout vs NDI
| Spout | NDI | |
|---|---|---|
| Best environment | Same Windows machine | LAN/network, multiple machines |
| Transport | GPU/shared texture | IP video |
| Network required | No | Yes |
| Cross-machine | Not the normal use case | Yes |
| HoloMapper | Input + output | Input + output |
Read NDI vs Spout for a deeper workflow comparison.
Frequently asked questions
Does HoloMapper support Spout?
Yes. HoloMapper currently supports Spout input and output on compatible Windows workflows.
Is Spout better than NDI?
Neither is universally better. Spout is ideal for local Windows app-to-app video sharing; NDI is designed to move video over IP networks and between machines.
Why is my Spout source black?
A common cause is the sender and receiver running on different GPUs. Also confirm the sender is active, the application versions are compatible and no plugin-specific setting is blocking output.
Sources and further reading
Product capabilities and platform notes can change. These official or primary sources are useful for checking current details:
