die "USAGE: $0 input\n" if scalar(@ARGV) < 1;
$| = 1;
$/ = \960;

open IN, "$ARGV0" or die "$ARGV0 : $!";
open OUT, ">tmp2";

my $y = 0;
my $value = '';

while (<IN>) { 
    my $bits = unpack("b*", $_);
    
    ## Replace '00' with '11' and vice versa
    $bits =~ s[(00|11)][ $1 eq '00' ? '11' : '00']ge;
    
    ## Discard any partial fraem from the front of the file.
    $bits =~ s/^(.*)(?=11111011000010001111011100010000)// if $. == 1;
    
    print OUT pack 'b*', $bits;
} 

close IN;
close OUT;