Modified to tolerate missing metadata.

flac2mp3

#!/usr/bin/ruby
# http://gist.github.com/gists/124242

filename = ARGV[0]
abort "Usage: flac2mp3 FLACFILE" if filename.nil?

`metaflac --export-tags-to=- "#{filename}"`.each_line do |s|
  v = s.strip.split '=', 2
  v[0].upcase!
  v[1].gsub! '"', '\"'
  eval %Q[#{v[0]} = "#{v[1]}"];
end

args = ""

if defined? TITLE
  args += %Q[ --tt "#{TITLE}"]
end

if defined? ARTIST
  args += %Q[ --ta "#{ARTIST}"]
end

if defined? ALBUM
  args += %Q[ --tl "#{ALBUM}"]
end

if defined? TRACKNUMBER
  args += %Q[ --tn "#{TRACKNUMBER}"]
end

if defined? GENRE
  args += %Q[ --tg "#{GENRE}"]
end

basename = File.basename(filename, File.extname(filename))

puts "Encoding #{basename}.mp3"
exec %Q[flac -sdc "#{filename}" | lame --alt-preset standard #{args} - "#{basename}.mp3"]