mp3.rb

#! /usr/bin/env ruby

# Checks to see if the given utility is installed
def installed?(util)
  %x(which #{util}).chomp!
end

# Makes the path or file friendly for UNIX environment
def make_friendly(file)
  file.gsub("'", "\\'").gsub('"', '\\"').gsub(" ", "\\ ")
end

# Checks to see if the given file extension is valid
def valid_filetype?(file)
  true if file =~ /.+\.(#{EXTENSIONS})/
end

# Creates a mp3 folder from the specified path, converts movie files
# and places the .mp3 output files inside the mp3 folder
def convert(file)
  mp3_file = file.gsub(/\.(#{EXTENSIONS})/,'') + '.mp3'
  %x(mkdir #{PATH}/mp3)
  %x(ffmpeg -i #{PATH}/#{file} -vn -ar 44100 -ac 2 -ab 192 -f mp3 #{PATH}/mp3/#{mp3_file})
end


# See if FFMPEG is installed on the system
unless installed?("ffmpeg")
  puts "ffmpeg is not installed on your system."
  puts "This software requires ffmpeg to convert video formats to mp3."
  puts "To install ffmpeg:"
  puts "on Mac:     sudo port install ffmpeg"
  puts "on Linux:   sudo apt-get install ffmpeg"
  exit
end

# Sets a temporary execute path
exe_path = File.expand_path(ARGV[0] || '.')

# Sets the RAW_PATH and RAW_FILE (if present)
if File.directory?(exe_path)
  RAW_PATH = exe_path
elsif File.exists?(exe_path)
  RAW_PATH, RAW_FILE = $1, $2 if exe_path =~ /(.+\/)(.+)/
end

# RAW_PATH and RAW_FILE are used for Ruby Methods
# PATH and FILE are used for UNIX utilities/commands and are properly escaped
# Sets the extensions, append more to support more video formats
PATH        = make_friendly(RAW_PATH)
FILE        = make_friendly(RAW_FILE) if defined?(RAW_FILE)
EXTENSIONS  = %w[mp4 flv mov wmv avi].join('|')

# Executes if a directory is targetted
if !defined?(FILE) and File.directory?(RAW_PATH)
  Dir.new(RAW_PATH).each do |file|
    if valid_filetype?(file)
      puts "Converting #{file}.."
      convert(make_friendly(file))
    end
  end
  exit
end

# Executes if a single file is targetted
if defined?(FILE) and File.exists?(File.join(RAW_PATH, RAW_FILE))
  if valid_filetype?(RAW_FILE)
    puts "Converting #{RAW_FILE}.."
    convert(FILE)
  end
  exit
end