VTT offset

vttoffset.rb

if ARGV.empty?
  puts "usage: #{$PROGRAM_NAME} offset [file] (or stdin)"
  exit 1
end

offset = ARGV.shift.to_i

ARGF.each_line { |l|
  unless l.include?('-->')
    puts l
    next
  end

  l.scan(/(\d\d):(\d\d):(\d\d)/).each { |h, m, s|
    t = h.to_i * 3600 + m.to_i * 60 + s.to_i - offset
    l["#{h}:#{m}:#{s}"] = Time.at(t).utc.strftime('%H:%M:%S')
  }
  puts l
}