Extracting audio length with Rails and ffmpeg

audio_length.rb

def self.get_audio_length(filepath)
pipe = "ffmpeg -i "+ filepath.to_s+" 2>&1 | grep 'Duration' | cut -d ' ' -f 4 | sed s/,//"
command = `#{pipe}`
  if command =~ /([\d][\d]):([\d][\d]):([\d][\d]).([\d]+)/
  #convert the result to only secs
  duration = ($2.to_i * 60) + $3.to_i
  end
#return and array containing the seconds and the human readable time length, ["6453","03:54"]
  return "#{duration.to_s},#{$2}:#{$3}".split(",")
end