Pixel Streaming Pipeline

What it is

A pipeline for streaming an Unreal Engine project to any device with a web browser, with no powerful local hardware needed on the viewer’s end — the server does all the rendering, the browser just handles input and displays the stream. Built as a custom Unreal Engine 4.26 source build with the Pixel Streaming plugin patches applied, plus a configured Node.js signalling server and Ngrok for public-internet exposure.

Built and shipped as Technical Artist at Lifelike & Believable in late 2020 to power the browser-based audience path on the LiViCi We Won’t Forget show. Used in production through 2021. The setup was involved enough that I wrote it up afterwards as a LinkedIn article and a YouTube tutorial so other Unreal users could replicate the same setup, plus a public GitHub gist of free STUN servers.

In short: a viewer on a phone, tablet, or weak laptop opens a URL and plays the same Unreal scene a powerful gaming PC is rendering — same input, same render, just streamed.

The problem

Unreal Engine projects need a powerful GPU to render. A viewer on a phone, tablet, or low-spec laptop can’t run them locally. For LiViCi We Won’t Forget, the show needed a remote audience path that worked on any device — viewers couldn’t be expected to have a VR headset or a gaming PC.

In late 2020, Pixel Streaming wasn’t shipped in the Unreal Engine editor. It existed as a plugin maintained inside Epic’s source tree but wasn’t bundled with public binary releases. Using it meant compiling Unreal from source with the plugin’s patches applied — and then standing up a Node.js signalling server, configuring STUN entries, and exposing the host to the public internet, none of which Epic’s docs walked through end-to-end. This pipeline put all of those pieces together into a repeatable workflow.

What it does

A browser sends inputs (clicks, key presses, touch joysticks on phones) to a packaged Unreal Engine executable running on a host PC. The Unreal process renders the scene and pipes frames back through the Pixel Streaming plugin to a Node.js signalling server, which negotiates a WebRTC connection to the browser. Ngrok tunnels the host’s port out to a public HTTPS URL with no static IP required — the free tier caps at ~40 concurrent users, enough for a curated audience like LiViCi’s.

How the pipeline runs (8 setup steps)

The setup runs in eight stages, from plugin activation through to a publicly-shareable URL. Each step’s how-to lives inside its collapsible below.

-AudioMixer -PixelStreamingIP=localhost -PixelStreamingPort=8888

 -AudioMixer -PixelStreamingIP=localhost -PixelStreamingPort=8888 -RenderOfScreen

Step 6 in detail (STUN + Public IP edits with screenshots)

Go to the engine install folder: UE_4.26 > Engine > Source > Programs and copy the PixelStreaming folder. Paste it inside the packaged project’s WindowsNoEditor folder.

Open PixelStreaming > WebServers > SignalingWebServer. Make a backup copy of Start_AWS_WithTURN_SignallingServer (just in case). Open the original file in a text editor.

STUN edit. Replace the first + $PublicIp + :19302 reference with a free STUN server. Pick one from my GitHub gist — for example, stun4.l.google.com:19302.

Public IP edit. Open cmd, type ipconfig, and copy the IPv4 Address value (something like 192.168.x.x on a LAN).

Back in the signalling server file, replace the second + $PublicIp + reference with that IP address.

Save the file as Start_AWS_WithTURN_SignallingServer.ps1. Run runAWS_WithTURN.bat to start the signalling server.

Step 7 in detail

Launch the packaged executable shortcut from Step 5. The signalling server from Step 6 should be running in the background. From any device on the same LAN — another PC, a phone, a tablet — open a browser and navigate to the host’s IPv4 address.

The scene should appear in the browser, interactive. One quality note: running the editor in-place looks pixelated in the stream, but the packaged executable renders cleanly.

Step 8 in detail (Ngrok auth + tunnel)

Sign up at https://ngrok.com (I linked mine to GitHub). Download Ngrok for Windows, extract the executable, and place it next to the packaged project.

First-time auth. Open the Ngrok console. From your Ngrok dashboard, copy the ngrok authtoken <key> command and paste it into the console. This writes your auth credentials to the local Ngrok config.

Tunnel the port. Pixel Streaming uses port 80, so run:

ngrok http 80

The console shows two Forwarding lines — an HTTP and an HTTPS URL pointing at *.ngrok.io. Share the HTTPS URL with anyone, anywhere. They open it in a browser and they’re inside your Unreal scene.

One gotcha: double-tapping Ctrl+C in the Ngrok console kills the tunnel instead of just copying. If that happens, just re-run ngrok http 80.

How it was used in production

This pipeline powered the browser-based audience path for LiViCi We Won’t Forget (2020 premiere → 2021 ongoing). A viewer with no VR headset and no gaming PC could open a link, see the live circus performance rendered on AWS, and interact in the same multiplayer audience as the VR users and the local-PC users.

The free Ngrok tier’s ~40 concurrent user ceiling was the audience size cap. For LiViCi’s invite-only curated audiences, that was the right ceiling. Scaling further would require a static IP and a paid hosting tier (AWS, GCP, or similar), which the show didn’t need for its scale.

Where it didn’t fit — Virtual Camera attempt

I tried adapting this pipeline for the Versatile Media Virtual Camera workflow — Pixel Streaming the live Unreal viewport to the iPad rig. The pipeline worked, but the latency was too high for fine cinematographic control: framing a shot needs sub-frame motion response, and the WebRTC round-trip plus encode/decode added enough delay that subtle framing felt rubbery. The VCam rig ended up using a dedicated low-latency video transmitter instead. Pixel Streaming is great for audience-facing experiences; not for operator-facing ones where input timing is on the critical path.

What it became — the tutorial

The setup was involved enough — eight steps across two software toolchains, plus a custom signalling-server edit and a Node.js dependency — that I wrote it up afterwards so the next Unreal user trying this in 4.26 wouldn’t have to piece it together themselves:

• LinkedIn article — full step-by-step text walkthrough with screenshots, published December 2020.
• YouTube tutorial — same setup as a video walkthrough, also December 2020.
• GitHub gist of free STUN servers — drop-in list so other users can configure their signalling server without hunting for a STUN provider.

In retrospect

Unreal Engine 4.27 (mid-2021) shipped Pixel Streaming as a stock plugin bundled with the editor, and Unreal 5.x matured it further. The custom 4.26 source-build approach this pipeline documents is now historical — anyone setting up Pixel Streaming today can skip Steps 3–5 entirely and just enable the bundled plugin. This page is a snapshot of what was needed before Epic built it in.