obs-rs

An OBS-style scene compositor and screen recorder, written in Rust on top of media-pp. Captures your desktop, composites it on the GPU, and records it — with an annotation layer you can draw on while it runs.

What it does

• Scenes and sources. A Scene is a list of sources placed on a 1920×1080 canvas. Move, resize, reorder, hide, lock and rename them. Duplicating a Scene places the same sources again rather than capturing them twice, so a source can appear in more than one Scene with its own position in each.
• Display and window capture on Windows and Linux. Frames go straight into GPU memory and stay there through compositing and encoding — the desktop never passes through system memory on its way to the recording. A captured window that is closed is not an error: the source waits where it is and picks the window up again when it comes back.
• Video capture. A webcam in a Scene, on both platforms — Media Foundation on Windows, Video4Linux2 on Linux. The camera states which picture sizes and rates it offers and the Properties dock lists them, or leave it on Automatic and take whichever the camera puts first. A camera that is unplugged is not an error: the source waits and opens it again when it comes back, as long as it goes into the same port — the device path a camera is stored by contains the one it was plugged into.
• Drawing. A source you draw on rather than one that captures something: pen, highlighter and eraser, with undo and clear. It is a real layer, so what you draw is in the recording, not just on your screen.
• Image. A still picture as a source, at its own size. Decoded once through the same library that opens a video, so whatever FFmpeg reads is a source — PNG, JPEG, WebP and the rest.
• Media file. A video file as a source, decoded on the GPU and composited like anything else, with its own channel in the audio mixer. It can be set to start again at its end; switching that off part way through lets the pass it is on play out rather than stopping where it is, and the Sources list says when one has finished — and play starts it again. It can be paused and scrubbed from the Properties dock, and seeking a paused clip moves the picture without starting it again.
• Network stream. An RTSP session in a Scene — an IP camera, usually — decoded on the GPU like a media file, with a channel in the mixer for its sound. A camera that stops answering is not an error: the stream is put back and tried again on its own, at an interval you choose, or left alone entirely if you turn that off. TCP or UDP, because no one transport gets through every network.
• Crop. Alt-drag a source's handle to cut into its picture instead of resizing it: the dragged edge moves, the opposite one stays, and what is being cut off shows faintly behind while you aim. Alt+double-click puts an edge back, and the Properties dock takes the four numbers exactly.
• Recording to MP4, Matroska or HLS, with hardware encoding where the machine has it. One recording can be split into several files by elapsed time or by size.
• Audio. Desktop and microphone channels with faders, mute, and level meters that read after the fader. A fader can boost past unity, and a lamp reports a channel that clipped. The Scene's own media files get a channel each — fader, mute and meter alike — so what a clip is playing can be set against everything else.
• Monitoring. Hear a media file, a stream or a microphone while you work. It goes to an endpoint you choose in Settings, kept separate from the one Desktop Audio is captured from so that what you are listening to does not end up in the recording twice. Switching a channel on or off does not interrupt what is playing. Everything monitored is still recorded — the switch is about your ears, not about the file. Desktop Audio has no such control: it is captured by listening to what your machine is already playing, so there is nothing there to play back.
• Properties. Selecting a source describes it in a dock of its own — where it sits, how large it is, and what it is actually capturing. A Color source's colour is edited there.
• A workspace that stays put. Docks can be moved, resized and closed, and where they were is remembered along with the window and the Preview's zoom. Launching obs-rs while it is already running brings that window forward rather than opening a second one.
• English and Korean, chosen from View → Language.

Using it

Add a source from the + under the Sources dock. A Display Capture asks which monitor and a Window Capture which window; on Wayland the system's own picker opens instead, and the choice is remembered so later runs do not ask again.

A Window Capture is stored as the window's program and title rather than as a handle, which only means something while that window is open. Closing the window empties the layer and reopening it fills it again — a browser you quit for the day is still in the Scene tomorrow.

Drag a source in the Preview to move it and its handles to resize it. Sources higher in the list are drawn in front of lower ones.

The Preview marks what it is showing you. The selected source is outlined in red, with the distance from each of its four edges to the edge of the canvas written alongside — the numbers for placing something exactly, centred or flush, instead of doing that arithmetic by eye. An edge that a crop cut is drawn in a green dashed line instead, so a cropped source does not read as merely a smaller one. Whatever hangs outside the canvas is hatched, being in the Scene but not in the recording. And the source under the pointer is outlined thinly in blue, which is the only way to tell what a click would take where one source covers another.

Double-click a source's name in the dock to change it, the same way a Scene's name is changed. The name belongs to the source rather than to the Scene, so one placed in two Scenes is renamed in both at once; a name already taken is refused where you typed it, and Escape leaves the old one alone.

Select a Drawing and the Preview's toolbar grows a pen. It stays in Select until you pick one, so a stray click cannot leave a mark. The eraser takes whole strokes rather than rubbing at pixels, and undo is the same thing aimed at the last one.

The Properties dock says what the selected source is: its name and kind, where it sits on the canvas and how large, and what it captures — the monitor and its place in the desktop, or the program and title of a window. Most of it reports rather than asks; a Color source's colour is the one thing edited there.

Start Recording writes to your Videos folder unless Settings says otherwise. What it records is the canvas, not the window — the selection outlines and the pen toolbar are editor-only and never appear in the file.

Keys, while the window has focus: Ctrl+R starts and stops recording, Ctrl+P pauses and resumes one, Ctrl+1 … Ctrl+9 switch to that Scene, F11 goes fullscreen, and Ctrl+, opens Settings. None of them fire while you are typing a name. All but the Scene keys can be changed in Settings → Hotkeys: click a binding, press the key you want, or Backspace to clear it.

File → Show Recordings opens that folder in your file manager, and File → Settings is the same dialog the Controls dock's button opens — there because that dock can be closed.

Settings has four pages: General, Video (output resolution and frame rate), Audio (sample rate and channels), and Recording (where files go, format, encoder, bit rates, splitting).

Getting it

A release carries one archive per platform. Unpack it and run what is inside; there is no installer, and nothing is written outside the folder you unpack it into except the settings and project files under your own user directory.

FFmpeg travels with the archive, so it does not have to be installed. What does have to be there:

Windows

• Nothing else. The Visual C++ runtime the executable needs is in the archive beside it.
• The executable is not code-signed, so SmartScreen will offer to protect you from it the first time. More info → Run anyway.

Linux

• An NVIDIA driver. Not for speed — for anything: see the note under Building. libcuda.so.1 comes from the driver and is deliberately not in the archive.
• PipeWire. libpipewire-0.3.so.0 is a client for a system service, so a bundled copy would only be a version to disagree with the one running. Every current desktop distribution has it.
• A glibc no older than the one the archive was built against, which is the current Ubuntu LTS. An older distribution needs a build from source.

Run ./obs-rs from the unpacked directory. It finds its own copy of FFmpeg beside it and needs no LD_LIBRARY_PATH.

For a name and an icon in the launcher, run ./install-desktop-entry.sh. It writes a desktop entry and an icon under ~/.local/share and needs no root. On Wayland this is the only way the window gets an icon at all — the protocol has no call for a client to set its own, so the compositor looks for an installed entry instead. Moving the folder afterwards breaks the entry, since it records where the executable is; run the script again, or --uninstall to remove it.

Building

cargo run --release

Beyond the Rust toolchain you need FFmpeg 8.0 or newer development headers. On Linux, desktop capture also needs PipeWire development files.

Linux needs an NVIDIA GPU. Not for a faster path — for the only one. The Linux backend composites on CUDA and there is no fallback, so obs-rs will not start on an AMD or Intel machine. The driver alone is enough; no CUDA toolkit, since it ships both the library and the PTX compiler. Windows uses D3D11 and has no such requirement.

Where it is up to

This is a working recorder, not a finished broadcaster. Worth knowing before you try it:

• No streaming. There is no RTMP output, so nothing goes to Twitch or YouTube yet. Recording is the whole of it.
• Eight source kinds. Display Capture, Window Capture, Video Capture, Media File, Network Stream, Image, Drawing and Color.
• No filters or transitions. Switching Scenes is a cut.

Contributing

docs/ARCHITECTURE.md describes how the application is put together — the Preview's terminology, the engine's threading and pipeline, how recordings are wired, and how localization works. AGENTS.md is the working guide for changing it.

License

Licensed under either the Apache License, Version 2.0 or the MIT License, at your option.

A released binary bundles FFmpeg's shared libraries, which are LGPL-2.1 and are built without GPL components. What that means, and where their source is, is in THIRD-PARTY.md. Building from source links against whatever FFmpeg your machine has, and none of it applies.