bms-to-song.rb

require 'tmpdir'
require 'digest'

# Returns the MP3 file name and other meta information about a BMS.
# XXX: This should be split into two functions.
def get_name(file)
  data = File.read(file, encoding: 'Shift_JIS')
  attrs = { }
  data.scan(/\n\s*?#(TITLE|GENRE|ARTIST|STAGEFILE)[ ]+(.+)/i) do
    attrs[$1.downcase] = $2.encode('UTF-8').strip
  end
  bname = File.basename(file, File.extname(file))
  name = "[#{attrs['genre']}] #{attrs['artist']} — #{attrs['title']}"
  name.gsub!(/[\/\\:\*\?"<>\|]/, '')
  [ name, attrs ]
end

# Takes a BMS package and returns an array of BMS files.
# If it’s a ZIP/RAR archive, extract them.
def bms_files(package, temp:)
  dir = begin
    if Dir.exist?(package)
      package
    else
      system '7z', 'e', "-o#{temp}", ARGV[0]
      temp
    end
  end
  Dir.chdir(dir) {
    Dir["*.[Bb][Mm][SELsel]"] + Dir["*.[Pp][Mm][Ss]"]
  }.map { |x| File.join(dir, x) }
end

# XXX: This code is very messy :(
#      Needs refactoring.
Dir.mktmpdir do |dir|
  used = { }
  bms_files(ARGV[0], temp: dir).sort_by { |x| x.scan(/h/i).length }.reverse.take(1).each do |file|
    tmpfile = File.join(dir, File.basename(file))
    out = "#{tmpfile}_bms2song.wav"
    s16 = "#{tmpfile}_bms2song.s8"
    mp3name, attrs = get_name(file)
    puts mp3name
    mp3 = "#{mp3name}.mp3"
    if File.exist?(mp3)
      puts "#{mp3} already exists -- skipping"
      next
    end
    puts "Rendering to #{out}"

    # XXX: Every keysound file must be 44.1k stereo.
    #      Maybe have this script convert them prior to invoking bms-renderer?
    #      Also, this is very slow. Perhaps should rewrite this part in C++.
    system 'bms-renderer', file, out

    # Failed attempt to skip duplicated file.
    system 'sox', out, '--no-dither', '-r', '8k', s16
    md5 = Digest::MD5.file(s16).hexdigest

    # XXX: Doesn’t work.
    if used[md5]
      puts "Already exists — skipping!"
      next
    else
      puts "Hash: #{md5}"
      used[md5] = true
      system 'wavegain', '-n', '-b2', '-y', out
      sf = File.join(dir, 'bms2songstage.png')
      # if attrs['stagefile']
      #   system 'convert', File.join(File.dirname(file), attrs['stagefile']), sf
      # end
      system('lame', '-b320',
        '--tt', attrs['title'] || '',
        '--ta', attrs['artist'] || '',
        '--tg', attrs['genre'] || '',
        # XXX: Adding album image killed the ID3 tags. Don’t know why.
        # *(File.exist?(sf) ? [ '--ti', sf ] : [ ]),
        out, mp3
      )
    end
  end
end