I'm not very familiar with PerlIO (:utf8, etc). I suspect that if you do

open IN, '<:utf8', $fn or ...;
binmode(IN);  # Short for binmode(IN, ':raw') in v5.8
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you will lose the :utf8 property. You could try

open IN, '<:raw:utf8', $fn or ...;
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but :raw and :utf8 might be mutually exclusive. Fortunately, it's easy to try these and see if they work.

Update: This page says the previous snippet will work. Your code would look like:

   local $/ = "\x0D\x0A";

   open(local *IN, '<:raw:utf8', $filename)
      or die("Unable to open input file $filename: $!\n");

   while (<IN>) {
      chomp;
      s/\x0A/ /g;
      ...
   }
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