motion

A node.js motion detection library that supports node.js streams

npm install motion
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Motion

A node.js motion detection library written in JavaScript that supports node.js streams.

Using motion streams requires ImageMagick CLI tools to be installed. There's plenty of ways to install ImageMagick, choose what's right for you.

Install

npm install motion

Streams

Usage

var MotionStream = require('motion').Stream;
var motion = new MotionStream();

mjpegconsumer.pipe(motion).pipe(filewriter);

Stream Options

  • minimumMotion: Number : The minimum number of seconds of motion required before emitting data
  • prebuffer: Number : The motion stream will emit the prebuffer number of seconds of images prior to motion occurring with motion data.
  • postbuffer: Number: The motion stream will emit the postbuffer number of seconds of images after motion occurs.

Motion Object

Usage

var Motion = require('motion').Motion;
var motion = new Motion();
var hasMotion = motion.detect(image1, image2);

Methods

detect(image1, [image2])

  • image1 Array of Number
  • image2 (optional): Array of Number

Detect is called with one or two flat arrays of RGBA values. If called with one parameter, detect will use the last image1 as image2.

var Motion = require('motion').Motion;
var motion = new Motion();

// img1, img2, img3, img4 created ... 
// all img's are strings of RGBA values
// and look like [128,128,128,255,...]

var hasMotion;

hasMotion = motion.detect(img1);
console.log(hasMotion);
// > false

hasMotion = motion.detect(img2);
console.log(hasMotion);
// > true

hasMotion = motion.detect(img3, img4);
console.log(hasMotion);
// > false

getLastImage()

Returns the last image.

var motion = new Motion();

console.log(motion.detect(img1));
// > false
console.log(motion.detect(img2));
// > true

console.log(img2 === motion.getLastImage());
// > true

getBlendedImage(image1, image2)

  • image1 Array of Number
  • image2 Array of Number

Returns an image with detected motion as white pixels on a black background in the form of a flat array of RGBA numbers.

About

Inspiration for this library comes from Romuald Quantin's excellent write up on motion detection in Javascript.

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