Probably roboticus solution is better, but anyway:

1. unpack your data as an hexadecimal string
2. use a hash to convert every three hexadecimal digits (12 bits) into two bytes (16bits).

use Data::Dumper;

my %t;
for my $i (0..63) {
    for my $j (0..63) {
        $t{sprintf "%03x", $i*64 + $j} = [$i, $j];
    }
}

my $buf;
my @bytes;
while (read STDIN, $buf, 4096) {
    my $hex = unpack "H*" => $buf;
    while ($hex =~ /(...)/g) {
        push @bytes, @{$t{$1}};
    }
}

print Dumper \@bytes;
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