#!/usr/bin/env ruby
#
# Simple script to extract the audio part of a video
# and encode it to mp3.
# Depends on 'mplayer' and 'lame' 

STDOUT.sync = true

name = ARGV[0]

abort("usage: #{$0} filename") if name.nil?
abort("a file name 'audiodump.wav' already exist") if File.exist? 'audiodump.wav'

ext = File.extname name
dir = File.dirname name

new_name = File.join dir, (File.basename(name,ext) + '.mp3')

puts ':: Start encoding...'
puts "   The new file will be:\n => #{new_name}"
puts '   Please wait.'

unless system("mplayer -vo null -ao pcm:fast '#{name}'")
  abort("Encoding failed. Make sure you have mplayer installed")
end

unless system("lame -b 192 audiodump.wav '#{new_name}'")
  abort("Encoding failed. Make sure you have lame installed")
end

puts ':: Removing audiodump.wav'
`rm -f audiodump.wav`

puts ':: End'