use PDF::API2;
use utf8::all;
use File::Basename;
my $oldfile = shift;
my $newfile = basename($oldfile, '.pdf') . '_new.pdf';

my $pdf = PDF::API2->open($oldfile);
my $item = $outline->outline();
$item->title('some chinese characters');
$item->destination($pdf->open_page(1));
$pdf->save($newfile);