Split a youtube playlist into playable files

split.vid.js

// post about this: https://medium.com/@xwildeyes/download-and-split-a-youtube-playlist-into-playable-files-e208e2a2e51b
// A script to split a youtube "playlist" file
// into it's mp3 parts, with corresponding filenames and
// everything
// By wildeyes.
// give it the name produced by youtube-dl -x https://www.youtube.com/watch?v=5nhp6ULk7mE
youtubeAudioFilename = process.argv[2]
// basically, a list of pairs of (time, name) in the format 00:00[:00] artist - song 
// see http://www.regexr.com/3bp42 for specs file example
specsFilename = process.argv[3]
exec = function (cmd) { return require("child_process").execSync(cmd, {stdio:[null, null, null]}).toString() }
fs = require("fs")
length = exec(`ffprobe -show_format "${youtubeAudioFilename}"`).split("duration=")[1].split("\n")[0]
songs = fs.readFileSync(specsFilename)
  .toString()
  .split("\n")
  .map(function(line) {
    descPart = line.match(/((?:\d:)?\d\d?:\d\d) (.*)/)
    return [descPart[1], descPart[2]]
  })
var i;
try {
  i = parseInt(fs.readFileSync('split.vid.js.error.log').toString().replace('split vid stopped at:', ''))
  console.log('found log, resuming from video ' + i)
} catch(err) {
  i = 0;
}
for(; i < songs.length; i++) {
  fromTime = songs[i][0]
  filename1 = songs[i][1]

  // fix for "no such file or directory" error from ffmpeg
  filename = filename1.replace('/','')

  if(i === songs.length - 1)
    toTime = length
  else {
    console.log (i + 1, songs[i + 1] )
    toTime = songs[i + 1][0]
  }

  shellLine = `ffmpeg -y -ss ${fromTime} -t ${toTime} -i "${youtubeAudioFilename}" -acodec libmp3lame -ab 128k "${filename}.mp3"`
  console.log(`Executing: ${shellLine}`);
  try {
    exec(shellLine);
  } catch(err) {
    console.log("writing position to file before exiting...")
    fs.writeFileSync("split.vid.js.error.log", "split vid stopped at:" + i);
    throw err
  }
}