Perl script to convert the National Geographic Magazine CNG file to JPG file and then converting the group of files in a folder to PDF document.

NGMCoverter.pl

use strict;
use warnings;
use PDF::API2::Lite;

my $basedir = "/Volumes/SEAGATE/NGM/NGM/200x";
my $ouputdir = "/Volumes/SEAGATE/NGM/Magazine";

process_files($basedir);

print "Completed.\n";

sub process_files {
    my $path = shift;

    opendir (DIR, $path)
        or die "Unable to open $path: $!";
    my @files = grep { !/^\.{1,2}$/ } readdir (DIR);
    closedir (DIR);
    @files = map { $path . '/' . $_ } @files;
  
	my $flag = 0;
    for my $listitem (@files) {
        if (-d $listitem) {
            process_files ($listitem);
        } else { 
            convertCNG2JPG($listitem);
			$flag = 1;
        }
    }
	if ($flag==1)
	{
		convertToPDF($path);
	}
}

sub convertCNG2JPG {
	my $file = shift;
	if($file =~ /cng$/){
		#print "Converted Filename : $file\n";
		my $ofile = (split(/\./,$file))[0].".jpg";
		#print "Converted Filename : $ofile\n";
		my $isValidCNG = 0;
		open OUTPUTFILE, ">", $ofile or die $!;
		binmode OUTPUTFILE;
	
		open INPUTFILE, "<", $file or die $!;
		binmode INPUTFILE;
	
		local $/ = undef;
		$/ = \(2**16);  # ignore line breaks, read in 1 MiB chunks
		while (<INPUTFILE>) {
		    $_ ^= "\xEF" x length;
		    die "Not a valid CNG file" if $. == 1 and not /^.{6}(JFIF|Exif)/s;        
		    print OUTPUTFILE;
		}
	
		close INPUTFILE;
	
		close OUTPUTFILE;
	}
	
}


sub convertToPDF{
	my $path = shift;
	chdir($path);
	my @tmp = split(/\//,$path);
	my $tmpname = $tmp[scalar(@tmp)-1];
	my $filename = (substr $tmpname, 0, 4)."_".(substr $tmpname, 4, 2)."_".(substr $tmpname, 6, 2).".pdf";
	#print "Filename : $filename\n";
	opendir my $dh, $path
	    or die "Can't opendir '$path': $!";
	my @jpg = grep -f "$path/$_" && /\.jpe?g/i, readdir $dh;
	closedir $dh
	    or die "Can't closedir '$path': $!";
	my $pdf = PDF::API2::Lite->new;
	my $counter = 0;
	for my $jpg ( sort @jpg ) {
		my $filesize = (-s "$path/$jpg") / 1024;
		#print "Size: $filesize\n";
		if ($filesize < 1024) {
		    my $image = $pdf->image_jpeg( "$path/$jpg" );	
		    $pdf->page( $image->width, $image->height );
		    $pdf->image( $image, 0, 0 );$counter++;
		}

	}

	$pdf->saveas("$ouputdir/$filename");
	print "Created File : $filename. with Pages : $counter\n";
}

Hello there,
I am clueless about perl and would like to ask how to use this please? I want to convert my nat geo so I can view i on my tablet.
Thank you very much

me too but have a slew of cng files to convert. I wish you'd come back and tell us poor fools more about what we need to do in order to get it done... hope to see you soon... thanks

I've got a tutorial on how to do this with a different code and Windows 7:
http://persuasivegraffiti.weebly.com/random/how-to-convert-national-geographic-cng-files-to-pdf
Hope this helps!