Convert .flac files to VBR mp3

flac2mp3.rb

#!/Users/duncanbeevers/.rvm/rubies/ruby-1.9.3-p0/bin/ruby

filenames = ARGV
abort "Usage: flac2mp3 FLACFILE, ( FLACFILE, ... )" if filenames.length < 1

require 'open3'

FIELD_NAMES = %w(TITLE ARTIST ALBUM TRACKNUMBER GENRE)
FIELDS      = FIELD_NAMES.map { |f| "(?:#{Regexp.quote(f)})" }.join("|")
MATCHER     = /^(#{FIELDS})=([^\n]+)\n$/


filenames.each do |filename|
  basename=File.basename(filename, File.extname(filename))

  metadata = {}

  Open3.popen3("metaflac", "--export-tags-to=-", filename) do |_, stdout, _|
    stdout.each_line do |s|
      match = MATCHER.match(s)
      if match
        metadata[match[1].upcase] ||= match[2].gsub('"', '\"')
      end
    end
  end

  puts "Encoding #{basename}.mp3"

  flac = [ "flac", "-sdc", filename ]
  lame = [ "lame", "--silent",
    "--alt-preset", "standard",
    "--tt", metadata["TITLE"]       || "",
    "--ta", metadata["ARTIST"]      || "",
    "--tl", metadata["ALBUM"]       || "",
    "--tn", metadata["TRACKNUMBER"] || "",
    "--tg", metadata["GENRE"]       || "",
    "-", "#{basename}.mp3"
  ]

  Open3.pipeline flac, lame
end