SFU (One-to-Many Streaming)

SFU (Selective Forwarding Unit) enables one Unreal Engine instance to stream to multiple viewers simultaneously.

Video Tutorial

Introducing Meeting Rooms

Architecture

In standard mode, each viewer gets a dedicated UE instance (1:1). With SFU:

• One UE instance renders the content

• The SFU server receives the stream and forwards it to multiple viewers

• One user is the Host (can send input to UE), all others are Players/Viewers (watch-only)

There is exactly one host per SFU session. The host is the only user who can send mouse, keyboard, and other input to the Unreal Engine application.

Roles

Host

The host controls the UE application. There is one host per SFU session. The host can send mouse, keyboard, and other input to UE.

await StreamPixelApplication({
  appId: 'your-project-id',
  sfuHost: 'true',
  AutoConnect: true,
});

Player (Viewer)

Players watch the stream but cannot send input to UE. Multiple players can connect simultaneously.

Players and viewers are watch-only. They cannot send any input (mouse, keyboard, touch, gamepad) to the Unreal Engine application.

await StreamPixelApplication({
  appId: 'your-project-id',
  sfuPlayer: 'true',
  AutoConnect: true,
});

Default (Neither)

When neither sfuHost nor sfuPlayer is set, the SDK uses standard 1:1 streaming.

Configuration via URL Parameters

SFU mode can also be set via URL query parameters, which is useful for sharing links:

https://yourapp.com/PROJECT_ID?sfuHost=true
https://yourapp.com/PROJECT_ID?sfuPlayer=true

You can also target a specific streamer instance:

https://yourapp.com/PROJECT_ID?sfuPlayer=true&streamerId=hostInstance123

Use Cases

• Live presentations: One person presents in UE, many watch

• Spectator mode: Players watch a game being played by the host

• Virtual events: Stream a virtual environment to a large audience

• Training/demos: Instructor controls the application, trainees observe

• Cost optimization: Serve many viewers from a single UE instance