Webcam

Start an MJPEG stream from a camera on the box

Start and stop an MJPEG video stream from a USB camera attached to the box. A person or a vision tool can then watch the DUT while a test runs.

Handle

use lager::LagerBox;

let lager = LagerBox::from_env()?;
let cam = lager.webcam("cam1");

Methods

Method	Description
name()	The net name this handle addresses
start()	Start the stream and return its URL
stop()	Stop the stream
status()	Whether a stream is running, and where
url()	The stream URL, or None when nothing is running

Types

pub struct WebcamStream {
    pub url: String,
    pub port: Option<i64>,
    pub already_running: bool,   // true when an existing stream was reused
}

pub struct WebcamStatus {
    pub running: bool,
    pub url: Option<String>,
    pub port: Option<i64>,
    pub video_device: Option<String>,   // e.g. "/dev/video0"
}

Method Reference

start() -> Result<WebcamStream>

Start the MJPEG stream. Idempotent: called while a stream is already up, it reports the existing one with already_running: true rather than starting a second.

let s = cam.start()?;
println!("watch at {} (reused: {})", s.url, s.already_running);

This call gets a 30-second budget, because starting the stream subprocess takes a few seconds.

stop() -> Result<bool>

Stop the stream.

Returns: false if no stream was active.

status() -> Result<WebcamStatus> and url() -> Result<Option<String>>

Whether a stream is active and where, or just the URL.

Examples

Record the bench while a long test runs

use lager::LagerBox;

let lager = LagerBox::from_env()?;
let cam = lager.webcam("cam1");

let stream = cam.start()?;
println!("::notice::watch the DUT at {}", stream.url);

let result = run_the_long_test(&lager);

cam.stop()?;
result?;

Supported Hardware

Camera	Notes
Logitech BRIO, C920, C922, C925e, C930e, C270, C615, StreamCam	Any UVC camera the box enumerates

Notes

• The stream URL points at the box as the client reached it. A URL captured on one network does not always resolve from another, so do not persist it across environments.
• This handle gives a video stream, not a frame grab. There is no assert-on-image here — point an MJPEG consumer (a browser, VLC, OpenCV) at the URL. To save one frame from a running stream, use lager webcam NET snapshot from the CLI.
• Always stop() in teardown. A running stream holds the camera open. A start on the same net reports the running stream. A stream on a different net that uses the same camera is refused until this one stops.