Ruby: Recursively convert to 128k MP3

convert.rb

#!/usr/bin/env ruby

# convert.rb
# Convert a directory (recursively!) full of audio files into 128k MP3.
# Good for burning folder-delimited MP3 CDs.
#
# Released under the license below (also at http://tomlea.co.uk/WTFBPPL.txt).
#
#
# DO WHAT THE FUCK YOU WANT TO + BEER/PIZZA PUBLIC LICENSE
# Version 1, May 2011
#
# Copyright (C) 2011 Tom Lea
#
#
# DO WHAT THE FUCK YOU WANT TO + BEER/PIZZA PUBLIC LICENSE
# TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
#
# 0. You just DO WHAT THE FUCK YOU WANT TO.
# 1. If you make a substantial amount of money by exercising clause 0,
#    you should consider buying the author a beer or a pizza.

def convert(source, destination)
  `ffmpeg -i "#{source}" -ar 44100 -ab 128k "#{destination}" > /dev/null 2>&1`
end

def convert_dir(path)
  # Get the full path.
  path = File.expand_path(path)
  puts "Searching for audio in \"#{File.basename path}.\""

  # Reject any invalids, like DS_Store | .. | .
  entries = Dir.entries(path).reject{|e| e =~ /^(\.{1,2})|(\.DS_Store)$/}
  # Ensure all the files in our array are full-paths.
  entries.collect!{|e|File.join(path, e)}

  entries.each do |entry|
    if File.directory?(entry)
      # If this entry is a directory, call our function with it and iterate
      # through its files.
      convert_dir(entry)
    else
      # Otherwise, proceed if it's a valid music file type.
      # Future: mime-type checking instead?
      unless File.extname(entry) =~ /(mp3|aac|m4a)$/
        puts "\"#{File.basename entry}\" not a valid audio file. Skipping."
        next
      end

      source, destination = generate_names(entry)
      puts "Converting #{source} to 128kbps MP3."
      convert(source, destination)

      File.delete(source)
    end
  end
end

def generate_names(filepath)
  # Store the full path to our file, and create a destination name.
  source = File.expand_path(filepath)
  extension = File.extname(source)
  source_base = source.chomp(extension)
  destination = "#{source_base}.mp3"

  # If there's going to be a naming conflict, handle it.
  if destination == source
    # Stick "old" in the filename.
    new_source = [source_base, extension].join('.old')
    File.rename(source, new_source)
    source = new_source
  end

  return source, destination
end

convert_dir(ARGV[0] || Dir.pwd)