tagMp3Podcast.rb

require 'mp3info'

# some test data, replace it with your own data
title = "After Dark #388: After Back to Work"
subtitle = "Merlin & Dan talk after Back to Work episode 104."
artist = "Dan Benjamin on 5by5.tv"
album = "After Dark"
genre = "Podcast"
track = 338
year = 2013

# you need this to handle iTunes correctly
# if the user drags the file into iTunes, it should be displayed as a podcast,
# not as a random music file
episode_guid = "http://5by5.tv/afterdark/338"
feed_url = "http://feeds.5by5.tv/afterdark"

# first chapter should start at time: <0>
# last chapter should end at time: <duration>
chapters = [
  {:title => "Chapter 1", :description => "Some description for Chapter 1", :start => 0, :end => 30},
{:title => "Chapter 2", :link => "http://www.5by5.com/2", :start => 30, :end => 60},
  ]




# open an mp3 file
Mp3Info.open("/Users/hering/5by5-chapters/afterdark-338.mp3") do |mp3|
  
  # Set ID3v1 Tags
  mp3.tag1.title = title if !title.nil?
  mp3.tag1.artist = artist if !artist.nil?
  mp3.tag1.album = album if !album.nil?
  mp3.tag1.year = year if year > 0
  mp3.tag1.tracknum = track if track > 0
  mp3.tag1.genre_s = genre if !genre.nil?
  
  # Set ID3v2 Tags
  mp3.tag2.title = title if !title.nil?
  mp3.tag2.TIT3 = subtitle if !subtitle.nil?
  mp3.tag2.artist = artist if !artist.nil?
  mp3.tag2.album = album if !album.nil?
  mp3.tag2.genre_s = genre if !genre.nil?
  mp3.tag2.tracknum = track if track > 0
  mp3.tag2.year = year if year > 0

  # This makes sure that if the user drags the file into iTunes, it is properly
  # displayed as a podcast and the feed can be subscribed to
  if (!feed_url.nil? && !episode_guid.nil?) then
    mp3.tag2.PCST = "\x00\x00\x00\x00"
    mp3.tag2.TGID = episode_guid
    mp3.tag2.WFED = "\x00#{feed_url}\x00"
  end
  
  # optionally remove current picture
  mp3.tag2.remove_pictures
  
  # add image as 'cover (front)' type
  # see: http://id3.org/id3v2.3.0#Attached_picture
  file = File.new('/Users/hering/5by5-chapters/cover.jpg','rb')
  mp3.tag2.add_picture(file.read, {:pic_type => 3, :mime => "image/jpeg", :description => "Cover"} )
  
  # create chapters and chapter toc
  # don't change! we have to do this binary style since the lib does not have
  # explicit suppport for that
  if (chapters.size > 0) then
    chaps = []
    ctoc = "toc1\x00"
    ctoc << [3, chapters.size].pack("CC")
    chapters.each_with_index do |ch, i|
      num = i+1
      title = ch[:title]
      description = ch[:description]
      link = ch[:link]
      
      ctoc << "ch#{num}\x00"
    
      chap = "ch#{num}\x00"
      chap << [ch[:start]*1000, ch[:end]*1000].pack("NN");
      chap << "\xFF\xFF\xFF\xFF\xFF\xFF\xFF\xFF"
    
      title_tag = [title.encode("utf-16")].pack("a*");
      chap << "TIT2"
      chap << [title_tag.size+1].pack("N")
      chap << "\x00\x00\x01"
    	chap << title_tag
    
      if !description.nil? then
      	description_tag = [description.encode("utf-16")].pack("a*")
        chap << "TIT3"
        chap << [description_tag.size+1].pack("N")
        chap << "\x00\x00\x01"
        chap << description_tag
      end
      
      if !link.nil? then
        chap << "WXXX"
        chap << [link.length+2].pack("N")
        chap << "\x00\x00\x00#{link}\00"
      end
    
      chaps << chap
    end
    mp3.tag2.CTOC = ctoc
    mp3.tag2.CHAP = chaps
  end
  
  # this is just to print out the tags
  #puts mp3
end
# once this blocks ends the file is saved automatically