"Ripple" shift the contents of an SBV file

ripple.pl

#!perl

# perl ripple.pl $ref $delta file.sbv

use strict;
use POSIX qw(floor);

# $ref is the time code (in seconds) where the ripple should start
my $ref = shift @ARGV;

# $delta is the duration (in seconds, can be fractional) that data should be shifted by.
# Positive values shift the data towards the end of the file, negative values shift
# the data towards the beginning of the file
my $delta = shift @ARGV;

my $timecode_pattern = qr/
    (\d):(\d\d):(\d\d)\.(\d\d\d)
    ,
    (\d):(\d\d):(\d\d)\.(\d\d\d)
/x;

sub code2sec {
    my ($h, $m, $s, $msec) = @_;
    return $h * 3600 + $m * 60 + $s + ($msec/1000);
}

sub sec2code {
    my ($sec) = @_;
    my $h = floor($sec) / 3600;
    my $m = floor($sec) / 60;
    my $s = floor($sec) % 60;
    return sprintf("%d:%02d:%02d.%03d",$h, $m, $s, ($sec - floor($sec))*1000)
}

my $in_text = 0;

while (<>) {
    if ($in_text) {
        if (/^\s*$/) {
            print "\n";
            $in_text = 0;
            next;
        }
        print "$_";
        next;
    }

    if (/$timecode_pattern/) {
        my $start = code2sec($1, $2, $3, $4);
        my $end   = code2sec($5, $6, $7, $8);
        if ($start >= $ref) {
            $start += $delta;
            $end += $delta;

            print sec2code($start), ",", sec2code($end), "\n";
            $in_text = 1;
           next;
        }
        print $_;
        next;
    }

    print $_;
}