From: John Miller <jfmiller28@...>
Date: 2007-08-28T01:12:42+09:00
Subject: Re: ID3 Tags (#136)

Here is my go at things:

__BEGIN__
#Note: this script assumes Ruby 1.8.6 style handeling of strings.  Some 
changes
#will need to be made for Ruby 1.9 to work correctly

require 'genre.rb' #an array of the official genera list

def id3(filename)
  id3 =  File.open(filename,'r') do |file|
    file.seek(-128,IO::SEEK_END) #get to the end of the file
    file.read(128)
  end
  return "" unless id3 #protect against read error
  if id3.slice(0,3) == "TAG"
     #Skip the first 3 bytes grab three thirty byte fields
     #and a 4 byte field dropping trailing whitespace.
     #While we can assume the old style comment field and
     #take 30 bytes (we'll com back for the track number later)
     #we must use 'Z' instead of 'A' to avoid having the track
     #show up in our comment field.
     #The last byte is the genre index.
    song,artist,album,year,comment,genre = id3.unpack 
"x3A30A30A30A4Z30C"
     #grab the track with a pain slice
    track = id3.slice(-2) if id3.slice(-3) == 0 && id3.slice(-2) != 0
    desc = "#{artist}: #{album}(#{year})\n"
    desc << "  #{song}.  "
    desc << "tr. #{track}" if track
    desc <<"\n"
    desc << "  Comment:  #{comment.chomp(" ")}\n" if comment.length != 0
    desc << "    Genre:  #{Genres[genre]}\n"
    return desc
  end

  return "" #tag not forund

end

#usage id3.rb filename [filename*]
ARGV.each do |filename|
  puts filename
  puts id3(filename) if File.exists? filename
  puts "\n"
end

__END__

I think the only real difference between what I'm seeing on this list 
and my own solution is the unpack string.  The 'Comment' filed must use 
'Z' and strip trailing white space separately otherwise the track number 
could get pulled and stuck on the end of the output.

I like the use of ARGF in other implementations.  Something new to put 
in my hat.

John Miller
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