use Encode qw/_utf8_on/;
my $a="bj\xc3\xb6rk";
_utf8_on($a);
my $binarystring=pack("V/a*", $a);
warn length $binarystring;
warn bytes::length $binarystring;

my $b="b"x1000;
_utf8_on($b);
my $binarystring2=pack("V/a*", $b);
warn length $binarystring2;
warn bytes::length $binarystring2;