Webcam auto timelapse

webcamlapse.js

#!/usr/bin/env node

var http = require('http')
  , url = require('url')
  , path = require('path')
  , fs = require('fs')
  , async = require('async')
  , exec = require('child_process').exec
  , imgUrl
  , options
  , dir
  , count
  , maxCount
  , delay
  ;

//////////////////////////////
//  Config
//////////////////////////////
imgUrl = 'http://webcam-cayeux.dyndns.org:8080/record/current.jpg';
imgUrl += '?rand=' + Math.floor(Math.random() * 1000000);
dir = __dirname + '/img';
count = 0;
maxCount = 500;
delay = 3000;
//////////////////////////////

options = {
    hostname: url.parse(imgUrl).hostname
  , port: url.parse(imgUrl).port || 80
  , path: url.parse(imgUrl).pathname
};

(function mkdir() {
  fs.mkdir(dir, function (err) {
    if (err) {
      if (err.code === 'EEXIST') {
        fs.rmdir(dir, mkdir);
      }
      else {
        throw err;
      }
    }
  })
}());

function downloadImg (cb) {
  var request, filename, stream;

  request = http.get(options, function (res) {

    fileName = path.join(dir, 'image_' + count + '.jpg');
    stream = fs.createWriteStream(fileName);

    res.pipe(stream);

    res.on('end', function (err) {
      if (err) throw err;
      console.log('Image ' + count + ' saved.');
      cb();
    });

  });

  request.on('error', function (err) {
    console.log('Oops, something went wrong: ' + err.message);
  });

}

function encodeMovie () {
  var movieName, cmd, child;

  movieName = 'webcam_timelapse.mp4';
  cmd = 'ffmpeg -start_number 0 -i img/image_%d.jpg -r 24 -vcodec h264 ' + movieName;

  fs.exists(movieName, function (exists) {
    if (exists) {
      fs.unlink(movieName, function (err) {
        if (err) throw err;
      });
    }
  });

  child = exec(cmd, function (err, stdout, stderr) {
    console.log('stdout: ' + stdout);
    console.log('stderr: ' + stderr);
    if (err !== null) {
      console.log('exec err: ' + err);
    }
    else {
      console.log('All done!');
    }
    process.exit();
  });

}

async.whilst(
  function () { return count < maxCount; },
  function (cb) {
    count++;
    setTimeout(function() {
      downloadImg(cb);
    }, delay);
  },
  function (err) {
    if (err) throw err;
    encodeMovie();
  }
);