Get rid of crap files in your music library and convert crap formats to mp3

cleanup.rb

KEEP_EXTS = [".mp3",".jpg",".mid",".MP3",".wma",".m4a",".JPG",".mpg",".JPEG",".m4v",".mp4",".mov",".flac"]
UNWANTED_EXTS = [".ini",".db",".txt",".md5",".nfo",".pls",".info",".sfv",".NFO",".SFV",".url",".bal",".ogg",".php",".m3u",".LOG",".sls",".log",".pdf"]
CONVERT_EXTS = [".wma"]

def files(path)
  Dir.glob("#{path}/**/*")
end

def find_files(path)
  files(path).map do |file|
    file if KEEP_EXTS.include?(File.extname(file))
  end.compact
end

def delete_unwanted_files(path)
  files(path).each do |file|
    if (UNWANTED_EXTS.include? File.extname(file))
      puts "Removing #{file}"
      File.delete(file)
    end
  end
end

def output_file(path)
  base_name = File.basename(path, ".*")
  dir_name = File.dirname(path)
  "#{dir_name}/#{base_name}.mp3"
end

def convert_files(paths)
  paths.each do |path|
    if CONVERT_EXTS.include?(File.extname(path))
      output_file = output_file(path)
      `ffmpeg -loglevel quiet -y -i "#{path}" -acodec mp3 -ab 128k "#{output_file}"`
      if $?.exitstatus == 0
        puts "Removing #{path}\n"
        File.delete(path)
      end
    end
  end
end

path = ARGV[0]

delete_unwanted_files(path)
files = find_files(path)
convert_files(files)

Neat!

You could eliminate your double quote hell in those arrays by using the array literal.

%w{.mp3 .jpg .mid .MP3}