youtube vids to mp3 files (ruby)

youtube-to-mp3.rb

#!/usr/bin/ruby

#usage:   youtube-to-mp3 <youtube-url>
#example: youtube-to-mp3 http://www.youtube.com/playlist?list=PL398CE05652474A1E
#desc:    downloads a single youtube vid or a playlist, then converts to mp3.
#         Requires youtube-dl and ffmpeg

url = ARGV[0]
system("youtube-dl -citA #{url}") 

Dir.foreach(".") do |file|
  filename = file[/(^\d{5}.*)[\-].*/,1]
  if filename != nil
    mp3_file = filename + ".mp3"
    system("ffmpeg -i \"#{file}\" -vn -acodec libmp3lame -ar 44100 -ac 2 -ab 128000 \"#{mp3_file}\"")
  end
end