youtube2srt_converter.rb

require 'rubygems'
require 'nokogiri'

youtube_xml = ARGV[0]
xml = File.open(ARGV[0])
srt = File.open(ARGV[1] || youtube_xml.gsub('.xml', '.srt'), 'w+')
doc = Nokogiri::XML(xml)

doc.children.children.each_with_index do |text, idx|

    ini = Time.at(text.attributes['start'].value.to_f)
    fi  = ini + text.attributes['dur'].value.to_f
    tz  = 7 #your timezone, mine is +7

    srt.write("#{idx+1}\n")
    srt.write("#{'%02d:%02d:%02d,%03d' % [ini.hour-tz, ini.min, ini.sec, ini.usec/1000]} --> #{'%02d:%02d:%02d,%03d' % [fi.hour-tz, fi.min, fi.sec, fi.usec/1000]}")
    srt.write("\n#{text.children.text}\n\n")
end

srt.close