fuse

streams vtube studio to any web page over webrtc w/ full transparency. uses NDI, AV1 encoding, and a WebGL shader to composite the alpha channel on the client.

Screen.Recording.2026-03-01.052253.mp4

how it works / flow

flowchart LR
  VTS[VTube Studio] -->|NDI RGBA| Fuse
  Fuse -->|AV1 stacked frame| WebRTC
  WebRTC --> Browser

  subgraph Browser
    direction TB
    Stream[stacked frame\ncolor top / alpha bottom]
    Stream --> Shader[WebGL shader\nsplits top=RGB bottom=alpha]
    Shader --> Output[transparent composite]
  end

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requirements

• Windows
• NDI Runtime (winget install NDI.NDIRuntime)
• FFmpeg (winget install Gyan.FFmpeg)
• Ideally, an Intel GPU for AV1 encoding. There is no implementation for any other GPU, but it will fallback to software encoding if needed.
• VTube Studio with NDI & NDI V5 enabled.

quick start

• run task (requires https://taskfile.dev) or download from releases
• open fuse.exe
• go to system tray, right click and select an NDI source
• open http://localhost:9090 in your browser or implement into your own app
• example implementation in example/ in Svelte.

config

variable	default	what it does
FUSE_PORT	9090	http port for signaling + static files
FUSE_FPS	30	target framerate
FUSE_BITRATE	8M	av1 encoding bitrate
FFMPEG_PATH	(auto-detect)	path to ffmpeg binary

resolution gets detected automatically from the ndi source.

troubleshooting

• no connection -- make sure fuse is running, check fuse.log for the http server line. make sure port 9090 isn't firewalled
• no video -- select an ndi source from the system tray. check fuse.log for pipeline started
• no transparency -- your browser needs webgl2. make sure the canvas has background: transparent
• high latency -- try lowering FUSE_BITRATE (e.g. 4M). hw encoder (av1_qsv) is way faster than software (libsvtav1)
• black/corrupt video -- prob a resolution mismatch. check fuse.log for "resolution changed"