#!/usr/bin/perl -pl
# time shift for srt subtitles

BEGIN {
    ($dt = shift @ARGV) != 0
        or print "Usage: $0 SECONDS file" and exit;
}

s{ (\d+) : (\d\d) : (\d\d) , (\d+) }
 { my @t = ($1, $2, $3, $4 + $dt * 1E3);
   $t[2] += $t[3] / 1E3; $t[3] %= 1E3;
   $t[1] += $t[2] / 60;  $t[2] %= 60;
   $t[0] += $t[1] / 60;  $t[1] %= 60;
   sprintf '%02d:%02d:%02d,%03d', @t;
 }gxe;