Download youtube video, convert it to mp3 and tag it

app.js

var ffmpeg = require("fluent-ffmpeg");
var taglib = require("taglib");
var ytdl = require("ytdl");
var fs = require("fs");

var url = 'http://www.youtube.com/watch?v=gXK5YpoadCU';

var title = "";
var authot = "";

ytdl.getInfo(url, function(err, info) {
  if (err) return done(err);
  console.log(info.title);
  console.log(info.author);
  title = info.title;
  author = info.author;
});
fs.exists("video.mp4", function(exists){
  if(!exists){
    var dl = ytdl(url,
      { filter: function(format) { return format.container === 'mp4'; } });
    dl.pipe(fs.createWriteStream('video.mp4'));
    dl.on('end', function () {
      console.log('File Saved');
      doConversion('video.mp4', 'audio.mp3');
    });
  } else {
    doConversion('video.mp4', 'audio.mp3');
  }
});

function doConversion(inFile, outFile){
  console.log("Starting conversion");
  var command = new ffmpeg({source: inFile})
    .on('start', function(commandLine) {
        console.log('Spawned FFmpeg with command: ' + commandLine);
    })
    .on('end', function() {
        console.log('Processing finished successfully');
        taglib.tag(outFile, function(err, tag){
          tag.title = title;
          tag.artist = author;
          console.log(tag);
          tag.saveSync();
        })
    })
    .withNoVideo()
    .toFormat('mp3')
    .withAudioBitrate('128k')
    .saveToFile(outFile);
}

package.json

{
  "name": "youtube-dl-ogg-testing",
  "version": "0.0.1",
  "private": true,
  "scripts": {
    "start": "node app.js"
  },
  "dependencies": {
    "ytdl": "*",
    "fluent-ffmpeg": "*",
    "taglib": "*"
  }
}