ffmpeg -i movie.avi ./pnm/%d.pnm

#!/usr/bin/perl

#my $fichier1 = 0;
my $nombredefichiers = `ls ./pnm/*.pnm | wc -l`;
my $count = 650;

my $j=0;while($j<50)
{
my ($sec,$min,$hour) = localtime(time);
my $date = $sec."-".$min."-".($hour);
        my $i=0;while($i<=1221135)
        {
        $fichier=int(rand($nombredefichiers)); 
        `dd if=./pnm/$fichier.pnm of=final-$date.pnm bs=1c count=$count 
        skip=$i seek=$i`;
        $i+=$count;
        }
$j++;
}