v4l2camera

node-v4l2camera

Capturing images from USB(UVC) webcam on linux machines.

Requirements

node >= 4.x
video4linux2 headers
c and c++ compiler with -std=c11 and -std=c++14
- gcc >= 4.9

Install

On linux machines:

npm install v4l2camera

package details: https://npmjs.org/package/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/bellbind/node-v4l2camera.git v4l2camera
cd v4l2camera
npm install
cd ../..

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