node-v4l2camera

Capturing images from USB (UVC) cameras on linux machines

Requirements

• node >= 20.x
• video4linux2 headers
• c and c++ compiler with -std=c11 and -std=c++17
  • gcc >= 11.4

Install

On linux machines:

npm install v4l2camera

• package details: https://www.npmjs.com/package/@dwe.ai/v4l2camera

Usage

var v4l2camera = require("v4l2camera");

var cam = new v4l2camera.Camera("/dev/video0");
if (cam.configGet().formatName !== "MJPG") {
  console.log("NOTICE: MJPG camera required");
  process.exit(1);
}
cam.start();
cam.capture(function (success) {
  var frame = cam.frameRaw();
  require("fs").createWriteStream("result.jpg").end(Buffer(frame));
  cam.stop();
});

For more detail see: examples/*.js (required "pngjs" modules)

API

Initializing and Configuration API

• var cam = new v4l2camera.Camera(device)
  • device: e.g. "/dev/video0"
• cam.formats: Array of available frame formats
• var format = cam.formats[n]
  • format.formatName: Name of pixel format. e.g. "YUYV", "MJPG"
  • format.format: ID number of pixel format
  • format.width: Frame width
  • format.height: Frame height
  • format.interval.numerator and format.interval.denominator : Capturing interval per numerator/denominator seconds (e.g. 30fps is 1/30)
• cam.configSet(format) : Set capture width, height, interval per numerator/denominator sec if the members exist in the format object
• cam.configGet() : Get a format object of current config

Capturing API (control flow)

• cam.start()
• cam.stop(afterStoped)
  • call re-config(format) or re-start() in afterStoped() callback
• cam.capture(afterCaptured): Do cache a current captured frame
  • use cam.frameRaw() in afterCaptured(true) callback

Capturing API (frame access)

• cam.frameRaw(): Get the cached raw frame as Uint8Array (YUYU frame is array of YUYV..., MJPG frame is single JPEG compressed data)
• cam.toYUYV(): Get the cached frame as Uint8Array of pixels YUYVYUYV... (will be deprecated method)
• cam.toRGB(): Get the cached frame as Uint8Array of pixels RGBRGB... (will be deprecated method)

Capturing API (camera frame info)

• cam.device: the device file name e.g. "/dev/video0"
• cam.width: pixel width of the camera
• cam.height: pixel height of the camera

Control API

• cam.controls: Array of the control information
• cam.controlGet(id): Get int value of the control of the id (id is one of cam.controls[n].id)
• cam.controlSet(id, value): Set int value of the control of the id
• var control = cam.controls[n]: Control spec
  • control.id: Control id for controlGet and controlSet
  • control.name: Control name string
  • control.type: "int", "bool", "button", "menu" or other types
  • control.max, control.min, control.step: value should be min <= v and v <= max and (v - min) % step === 0
  • control.default: default value of the control
  • control.flags: Several bool flags of the controls
  • control.menu: Array of items. A control value is the index of the menu item when type is "menu".

Build for Development

On linux machines:

cd myproject
mkdir -p node_modules
cd node_modules
git clone https://github.com/DeepWaterExploration/node-v4l2camera.git v4l2camera
cd v4l2camera
npm install
cd ../..

"build/Release/v4l2camera.node" is exist after the build.

Licenses

MIT and LGPL-3.0 dual