webp-carve.pl

#!/usr/bin/perl -w
use strict;
use warnings;

my $header = 'RIFF';
my $sbuf = 1024;

open my $file, '<', $ARGV[0] or die $!;
binmode $file;
my $i = 0;
while (<$file>) {
    seek($file, $i, 0);
    my $buf;
    read $file, $buf, $sbuf;
    my $y = index $buf, $header;
    if ($y != -1) {
      $i += $y + 4;
      seek $file, $i, 0;
      read $file, $buf, 6;
      my $size = unpack("V", $buf) + 8;
      seek $file, ($i - 4), 0;
      read $file, $buf, $size;
      open(my $out, ">", $ARGV[1]) or die $!;
      print $out $buf;
      close $out;
      $buf = undef;      
    }
    $i += $sbuf - length($header);
}
close $file;