bradoconnor.rb

#! /usr/bin/ruby

require 'optparse'
options = {}
optparse = OptionParser.new do |opts|
  options[:operation] = 'add'
  opts.on('--operation OPERATION') {|operation| options[:operation] = operation}
  options[:time] = '00,000'
  opts.on('--time TIME') {|time| options[:time] = time}
end
optparse.parse!
secs, millisecs = options[:time].split(",")
offset = secs.to_i * 1000 + millisecs.to_i
offset = -offset if options[:operation] == 'subtract'
files=[]
ARGV.each {|file| files << file}
srt_array=[]
srt_file = File.open(files[0],"r")
while line=srt_file.gets
  srt_array < \d\d:\d\d:\d\d,\d\d\d/
    times = line.chomp.split(/ --> /)
    new_time = []
    times.each do |time|
      hours, mins, secs = time.split(":")
      secs, millisecs = secs.split(",")
      total_millisecs = hours.to_i * 3600000 + mins.to_i * 60000 + secs.to_i * 1000 + millisecs.to_i
      total_millisecs += offset
      total_millisecs = [0,total_millisecs].sort.last
      hours, total_millisecs = total_millisecs.divmod(3600000)
      mins, total_millisecs = total_millisecs.divmod(60000)
      secs, millisecs = total_millisecs.divmod(1000)
      new_time << ("%02d" % hours) + ":" + ("%02d" % mins) + ":" + ("%02d" % secs) + "," + ("%03d" % millisecs)
    end
    new_srt_array < " + new_time[1]
  else
    new_srt_array << line
  end
end
output_file = File.new(files[1],"w")
output_file.puts new_srt_array
output_file.close