Lenny

Use your phone as a webcam. The phone app streams its camera to the Lenny desktop app over Wi-Fi, and the desktop app is where you pick the camera, resolution, frame rate, focus and exposure.

 

Status

Version 1.0. Android phone → Windows 10/11 PC works end to end, including the virtual camera other apps see. The core and the desktop app are Rust (ADR-0006, ADR-0007); the phone app is still Flutter for now.

What works today:

• Virtual camera "Lenny" on Windows: a DirectShow camera (Windows 10 and 11) and a Media Foundation one (Windows 11), tested with Edge/Chrome (getUserMedia) and OpenCV. Zoom, Teams, Discord and OBS in a real call: not tried yet.
• Live H.264 over Wi-Fi, USB tethering or USB (adb), around 30 ms on 5 GHz Wi-Fi or a cable.
• Connecting: scan the QR code on the PC, tap Find PCs, or type the address. Phones you allowed once reconnect by themselves, also after sleep, app switches or a PC restart.
• Camera control from the PC: lens (0.6× / 1× / 2× / front, whatever the phone has), zoom, pan where the phone allows it, focus Auto or tap to focus, exposure and exposure lock, torch.
• Aspect, resolution (up to 4K) and frame rate (up to 60 fps on phones with high-speed video), from what each lens really supports, switched live.
• Phone name and battery on the PC.

Not there yet: OBS plugin, iOS phone app, Linux on a real v4l2loopback (built, only tested with a null camera), encryption. macOS is out of scope.

Testing notes live in docs/testing.md. The wire protocol is at 1.1 (protocol.md §11).

Try it

Get Lenny-Setup-<version>.exe (Windows) and Lenny-Android.apk from the Releases page.

1. Install the phone app, run the Windows installer (it asks for admin once: camera, background service, firewall rule) and open Lenny on the PC.
2. On the phone, tap Scan QR and point it at the code on the PC (or Find PCs). Phone and PC need the same network, or USB tethering.
3. The first time, allow the phone on the PC.
4. In Zoom / Teams / Discord / the browser, pick the camera Lenny.

Uninstall from Windows Settings → Apps. Files a running app still holds (the camera DLL) go at the next restart.

Build

Needs Flutter (stable), Android Studio (SDK + NDK), Rust (stable) with the Android targets and cargo-ndk, and, for Windows, Visual Studio 2022 with the C++ workload.

rustup target add aarch64-linux-android armv7-linux-androideabi x86_64-linux-android i686-linux-android
cargo install cargo-ndk

cd app
flutter build apk --release        # app/build/app/outputs/flutter-apk/app-release.apk
flutter build appbundle --release  # app/build/app/outputs/bundle/release/app-release.aab

Windows desktop + installer (needs NSIS and rustup target add i686-pc-windows-msvc for the 32-bit camera DLL):

powershell -File installer\build.ps1   # target\Lenny-Setup-<version>.exe

Core library tests (Rust; the Android build runs cargo-ndk for you):

cargo test --workspace
core/tools/abi_check.sh   # the Rust core still exports exactly include/lenny/lenny.h (needs cbindgen, clang)

Linux desktop (Rust, same app):

cargo run --release -p lenny_desktop                     # the app; falls back to a null virtual camera without v4l2loopback
sudo modprobe v4l2loopback exclusive_caps=1 card_label=Lenny   # for a real /dev/videoN other apps can open
cargo run -p lenny_desktop --example fake_phone -- 127.0.0.1 47474   # no phone at hand

How it's built

Part	What
core/	Rust library shared by every platform: protocol, sessions, pairing, clock sync. C ABI (include/lenny/lenny.h).
desktop/	Rust desktop app (egui), Windows and Linux.
vcam/	Virtual camera behind one trait: Windows shared-memory writer, v4l2loopback on Linux, a null backend.
vcam/com/	The Windows camera DLL (DirectShow filter + Media Foundation source), Rust, x64 and x86.
framebuf/	The shared-memory frame ring between the app and the camera DLL.
installer/	NSIS installer and uninstaller (ADR-0008).
app/	Flutter phone app (Android).
plugins/android_camera	Camera2 capture + MediaCodec H.264 encoder (Kotlin + JNI).

More: architecture, wire protocol, design system, testing.

License

GPL-3.0. Use it, change it, share it; anything built on it stays open source too.