android-obs-streamer

Turn your old Android phone into a low-latency USB webcam for OBS Studio.

Two parts:

1. Android app (app/) — Camera2-based capture that publishes JPEG frames over the network on two ports:
   • 4748 — raw TCP, length-prefixed frames (low latency)
   • 4747 — MJPEG over HTTP (works with OBS Media Source, browsers, VLC, etc.)
2. Native OBS plugin (obs-plugin/native/) — A C plugin that decodes the stream directly into OBS as an async video source. Ships with bundled adb binaries so USB mode "just works" without manual port-forwarding.

Features

Android app

• Camera2 capture with selectable resolution and 15/24/30/60 FPS
• Front and back cameras, torch, ring-light overlay (front camera, with brightness slider)
• Tap-to-focus, autofocus on/off, AE lock, exposure compensation
• Auto-rotation that re-orients the JPEG stream to match the device
• Wake lock so the phone never sleeps mid-stream
• Slide-out drawer UI so the camera preview fills the screen
• Can be launched as a HOME app
• Two transports running simultaneously: HTTP MJPEG (4747) and raw TCP (4748)
• Black-screen mode (privacy)
• ADB and Wi-Fi both supported

OBS plugin

• Native C plugin (no Python script, no Media Source hacks)
• Three connection modes selectable per source:
  • USB (auto-forward via ADB) — bundled adb runs adb forward for you
  • Wi-Fi — Raw TCP (low latency)
  • Wi-Fi — HTTP MJPEG (legacy)
• Sub-50 ms latency in raw TCP mode (TCP_NODELAY, no MJPEG re-encoding overhead)
• Auto-reconnect
• Cleans up adb on OBS exit (adb kill-server in obs_module_unload)
• Source appears in OBS's + picker as "Android USB Cam" with the camera icon

Quick start

1. Install the Android app

Grab app-debug.apk from the latest dev-latest release and sideload it. Grant camera permission, tap Start.

2. Install the OBS plugin

Grab obs-android-usbcam-installer.exe from the same release and run it. It auto-detects your OBS install directory.

3. Add the source in OBS

• + in the Sources dock → Android USB Cam
• Default mode is USB. Plug the phone in, enable USB debugging, tap Start in the app, click OK in OBS. You should see the feed within a second.

For Wi-Fi mode: switch the Connection dropdown to one of the Wi-Fi options and type the phone's IP into the Host field. The Android app's status bar shows both URLs.

Build from source

Android app

./gradlew assembleDebug
# → app/build/outputs/apk/debug/app-debug.apk

CI builds and uploads the APK to the dev-latest pre-release on every push to claude/**.

OBS plugin (Linux)

sudo apt install libobs-dev cmake build-essential
cd obs-plugin/native
cmake -B build -DLIBOBS_INCLUDE_DIR=/usr/include/obs
cmake --build build -j$(nproc)
sudo cp build/obs-android-usbcam.so /usr/lib/x86_64-linux-gnu/obs-plugins/

OBS plugin (Windows)

The Windows build is heavyweight because it goes through the official obs-plugintemplate CI flow to fetch prebuilt obs-deps and qt6. Easiest is to let GitHub Actions do it — see .github/workflows/build-obs-plugin.yml.

Protocol

Raw TCP (port 4748)

"ACAM"                       (4 bytes magic, sent once on connect)
[uint32 BE size][JPEG data]  (repeating, big-endian frame size)

Single client at a time. The Android side closes the previous session when a new client connects.

HTTP MJPEG (port 4747)

Standard multipart/x-mixed-replace; boundary=frame. The plugin parses it by scanning for JPEG SOI (FF D8) / EOI (FF D9) markers, so any boundary string works.

Repo layout

android-obs-streamer/
├── app/                              Android Kotlin app (Camera2)
│   └── src/main/java/com/example/usbcam/
│       ├── MainActivity.kt           UI, drawer, wake lock, orientation
│       ├── CameraStreamer.kt         Camera2 wrapper, JPEG rotation, AE/AF
│       ├── MjpegServer.kt            HTTP server on 4747
│       ├── StreamSession.kt          HTTP multipart writer
│       └── RawStreamServer.kt        Raw TCP server on 4748
├── obs-plugin/
│   ├── native/                       C plugin (the real one)
│   │   ├── src/plugin.c              Main plugin source
│   │   ├── src/stb_image.h           Bundled JPEG decoder
│   │   ├── installer/installer.nsi   NSIS installer (Windows)
│   │   └── CMakeLists.txt
│   └── android-usbcam.py             (legacy Python script, kept for reference)
└── .github/workflows/
    ├── build.yml                     Android APK build
    └── build-obs-plugin.yml          Linux .so + Windows .dll + installer

License

MIT.