nokhwa

Nokhwa(녹화): Korean word meaning "to record".

A Simple-to-use, cross-platform Rust Webcam Capture Library

Using nokhwa

Nokhwa can be added to your crate by adding it to your Cargo.toml:

[dependencies.nokhwa]
// TODO: replace the "*" with the latest version of `nokhwa`
version = "*"
// TODO: add some features
features = [""]

Most likely, you will only use functionality provided by the Camera struct. If you need lower-level access, you may instead opt to use the raw capture backends found at nokhwa::backends::capture::*.

Example

// set up the Camera
let mut camera = Camera::new(
    0, // index
    Some(CameraFormat::new_from(640, 480, FrameFormat::MJPEG, 30)), // format
)
.unwrap();
// open stream
camera.open_stream().unwrap();
loop {
    let frame = camera.get_frame().unwrap();
    println!("{}, {}", frame.width(), frame.height());
}

A command line app made with nokhwa can be found in the examples folder.

API Support

The table below lists current Nokhwa API support.

• The Backend column signifies the backend.
• The Input column signifies reading frames from the camera
• The Query column signifies system device list support
• The Query-Device column signifies reading device capabilities
• The Platform column signifies what Platform this is availible on.

Backend	Input	Query	Query-Device	Platform
Video4Linux(input-v4l)	✅	✅	✅	Linux
MSMF(input-msmf)	✅	✅	✅	Windows
AVFoundation(input-avfoundatuin)^^	✅	✅	✅	Mac
libuvc(input-uvc)	✅	✅	✅	Linux, Windows, Mac
OpenCV(input-opencv)^	✅	❌	❌	Linux, Windows, Mac
IPCamera(input-ipcam/OpenCV)^	✅	❌	❌	Linux, Windows, Mac
GStreamer(input-gst)	✅	✅	✅	Linux, Windows, Mac
JS/WASM(input-wasm)	✅	✅	✅	Browser(Web)

✅: Working, 🔮 : Experimental, ❌ : Not Supported, 🚧: Planned/WIP

^ = No CameraFormat setting support. ^^ = No FPS setting support.

Feature

The default feature includes nothing. Anything starting with input-* is a feature that enables the specific backend. As a general rule of thumb, you would want to keep at least input-uvc or other backend that has querying enabled so you can get device information from nokhwa.

input-* features:

• input-v4l: Enables the Video4Linux backend. (linux)
• input-msmf: Enables the MediaFoundation backennd. (Windows 7 or newer)
• input-avfoundation: Enables the AVFoundation backend. (MacOSX 10.7)
• input-uvc: Enables the libuvc backend. (cross-platform, libuvc statically-linked)
• input-opencv: Enables the opencv backend. (cross-platform)
• input-ipcam: Enables the use of IP Cameras, please see the NetworkCamera struct. Note that this relies on opencv, so it will automatically enable the input-opencv feature.
• input-gst: Enables the gstreamer backend. (cross-platform)
• input-jscam: Enables the use of the JSCamera struct, which uses browser APIs. (Web)

Conversely, anything that starts with output-* controls a feature that controls the output of something (usually a frame from the camera)

output-* features:

• output-wgpu: Enables the API to copy a frame directly into a wgpu texture.
• output-wasm: Generate WASM API binding specific functions.
• output-threaded: Enable the threaded/callback based camera.

Other features:

• decoding: Enables mozjpeg decoding. Enabled by default.
• small-wasm: Enables size optimizations for WASM targets. Uses wee_alloc instead of default, LTO enabled, opt-level set to "s" for size. Note that the LTO and opt-level are only enabled if:
  • --release is enabled.
  • The target family is wasm
  • --no-default-features is enabled. (disables mozjpeg and MJPEG processing)

Please use the following command for wasm-pack in order to get a functional WASM binary:

wasm-pack build --release -- --features "input-jscam, output-wasm, small-wasm, test-fail-warning" --no-default-features 

• docs-only: Documentation feature. Enabled for docs.rs builds.
• docs-nolink: Build documentation without linking to any libraries. Enabled for docs.rs builds.
• test-fail-warning: Fails on warning. Enabled in CI. You many want to pick and choose to reduce bloat.

Issues

If you are making an issue, please make sure that

• It has not been made yet
• Attach what you were doing, your environment, steps to reproduce, and backtrace. Thank you!

Contributing

Contributions are welcome!

• Please rustfmt all your code and adhere to the clippy lints (unless necessary not to do so)
• Please limit use of unsafe
• All contributions are under the MPL 2.0 license unless otherwise specified

Minimum Service Rust Version

nokhwa may build on older versions of rustc, but there is no guarantee except for the latest stable rust.