AACInfo - Ruby

aacinfo.rb

##
# Name: AACInfo
# Author: Matthew Loberg
# Author URL: http://twitter.com/mloberg
# Description:
#   I couldn't get MP4Info to read the tags of my iTunes music files, so I created this little class.
#   It uses faad to get the tag info, so make sure it's installed (brew install faad2)
require 'iconv'

class AACInfo

	def self.open(file)
		self.new(file)
	end
	
	def initialize(file)
		raise "No such file" unless File.exist?(file)
		@file = file
		@tags = {}
		parse_info
	end
	
	def method_missing(id)
		key = id.to_sym
		return @tags[key] if @tags.has_key? key
		nil
	end
	
	private
	
	def parse_info
		ic = Iconv.new('UTF-8//IGNORE', 'UTF-8')
		# get info with faad
		info = ic.iconv(`faad -i "#{@file}" 2>&1` + ' ').split(@file + " file info:\n\n").last.split("\n")
		
		# get the track length
		@tags[:length] = info.shift[/\d+\.\d{1,3}/]
		
		# there is a blank line, delete it
		info.shift
		
		# go through each tag and save it to the instance variable
		info.each do |tag|
			next unless tag =~ /^(\w|\d)+:./
			key, *value = tag.split(": ")
			@tags[key.to_sym] = value.join(": ")
		end
	end

end

example.rb

#
# Your system must have faad installed on it for this to work.
#  If you're running homebrew, brew install faad2
#

require './accinfo'

song = AACInfo.open('your song.m4a') # or AACInfo.new('your song.m4a')

puts song.length
puts song.title
puts song.artist
puts song.album