mp3とwavを相互変換する

wavmp3.rb

#!/usr/bin/env ruby

def usage
  $stderr.puts "usage: wavmp3 file [file ...]"
  exit 1
end

usage if ARGV.size < 1

ARGV.each do |f|
  /(\..+?)$/ =~ f 
  next if $1.nil?
  case $1.downcase
  when ".mp3"
    d =f.sub(/\..+?$/, ".wav")
    system %!ffmpeg -i "#{f}" -vn -ac 2 -ar 44100 -acodec pcm_s16le -f wav "#{d}"!
  when ".wav"    
    d =f.sub(/\..+?$/, ".mp3")
    system %!ffmpeg -i "#{f}" -vn -ac 2 -ar 44100 -ab 192k -acodec libmp3lame -f mp3 "#{d}"!
  end
end