mp3_renamer.rb

# gem install ruby-mp3info
require 'mp3info'

# Formato: # Pista [espacio] Nombre
# Ejemplo de filtros:
# Antes: 05 - Run Run Run - The Velvet Underground.mp3
# filters = ["- ", " - The Velvet Underground"] 
# Después: 05 Run Run Run.mp3

def prepare(name)
  filters = [""]
  filters.each { |f| name = name.sub(f, "") }
  ext = File.extname(name)
  name = name.sub(ext, "")
  name = name.gsub(/\b('?[a-z])/) { $1.capitalize }
  name += ext 
end

def get_tracknum(name)
  name[0..name.index(" ")].to_i
end

def get_trackname(name)
  ext = File.extname(name).length + 1
  name[(name.index(" ") + 1)..(name.length - ext)]
end

Dir.entries(".").each do |file|
  if File.file?(file) && File.extname(file).casecmp(".mp3") == 0
    new_file = prepare(file)
    File.rename(file, new_file)
    Mp3Info.open(new_file) do |mp3|
      mp3.tag.tracknum = get_tracknum(new_file)
      mp3.tag.title = get_trackname(new_file)
      # mp3.tag.artist = "The Velvet Underground"
      # mp3.tag.album = "The Velvet Underground & Nico"
    end
  end
end