余計な機能がついてるのは別のライブラリの一部として作ったため require 'stringio' StringIO.class_eval do def read_format(size, format) bin = read(size) bin = "\000" + bin if size == 3 bin.unpack(format).first end end module Video class WrongFormatError < StandardError; end class Flv attr_accessor :body, :title def initialize @header = {} end def save(path) File.open(path, 'wb') do |f| f.write @body end end def mp3 mp3 = MP3.new