my $fParse = "$dirCapture"."r.pcap";
# open an existing pcap file to analyze
my $pktParse = Net::Frame::Dump::Offline->new(file => $fParse, keepTimestamp => 1);
$pktParse->start;

my $count = 0;
while (my $h = $pktParse->next) {
  # get each packet in the file
  my $frmSimple = Net::Frame::Simple->new(
     raw        => $h->{raw},
     firstLayer => $h->{firstLayer},
     timestamp  => $h->{timestamp},
  );

  my $len = length($h->{raw});
  #-----------> until here $len is correct
  # write this packet to pcap file
  my $w = Net::Frame::Dump::Writer->new(
     file       => "$dirMerge"."rrr.pcap",
     firstLayer => 'ETH',
     overwrite  => 1); 
  $w->start;
  $w->write({ timestamp => $h->{'timestamp'}, raw => $h->{'raw'} });
  # --------> but after here, packet length in new writing file is not correct, it's only 1500 bytes, while the correct one is 1514
  $w->stop;
  $count++;
}
$pktParse->stop;