srt_converter.rb

#!/bin/ruby

require 'rubygems'
require 'bundler'
Bundler.setup(:default)
require 'srt'

file = SRT::File.parse(File.new(ARGV[0]))
outfile_name = File.basename(ARGV[0], '.srt') + '.txt'

File.open(outfile_name, "w") do |f|
  file.lines.each do |line|
    f.puts line.text.join(" ")
  end
end