[H-GEN] For those at the meeting late last Saturday

[Tomas Marko Miljenović]

Finally. Thanks for nothing, you ethernet frame-abusing so-and-so's at Lenkeng. I hope those extra bytes from the trailer and FCS result in a huge improvement in speed and image quality.

For posterity, sample code to extract one frame is included below. (Yes, everyone needs the necessary privileges/capabilities for libpcap just to capture some damn video.)


#!/usr/bin/perl -w

use strict;
use Net::PcapUtils;

use constant {
  PACKET_LENGTH => 1066,
  HEADER_STRIP_LENGTH => 46,
  JPEG_PACKET_DATA_LENGTH => 1020, # 1066 - 46
  ETHERNET_DEVICE => 'em1'
};

my $count = 0;

sub process_pkt {
  my($arg, $hdr, $pkt) = @_;
  my $jpeg_data = substr($pkt, HEADER_STRIP_LENGTH, JPEG_PACKET_DATA_LENGTH);  
  if($jpeg_data =~ /JFIF/){
    $count++;
    if($count>1){die}
  }
  print $jpeg_data;
}

Net::PcapUtils::loop(\&process_pkt, DEV => ETHERNET_DEVICE, SNAPLEN => PACKET_LENGTH, FILTER => 'port 2068');
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