I think TedPride has the right idea. Setting $INPUT_RECORD_SEPERATOR to undefined (undef $/) has the effect of causing the while(<IN> statement to slurp the entire three+ gig file at once. From the docs

"Entirely undefining $/ makes the next line input operation slurp in the remainder of the file as one scalar value"

Set $/ to some reasonable size, maybe to satisfy memory limitations. Then you can match blocks of the file in much the way TedPride describes. Something like this

#undef $/;
$/ = \2048;         # 2K blocks
my $blocksz = 2048;

open IN, "tmp";
open OUT, ">>$ARGV[1]";   #more efficient when parsing more than one b
+lock

#Extract the necessary data bits
my $block01 = <IN>;
my $block02 = '';
while ($block02 = <IN>) {

     my $block = $block01.$block02;
     $block =~ s/11110100.{8}(.{1520})11110100.{8}(.{464}).{1056}/$1$2
+/g;

#     $_ =~ s/11110100.{8}(.{1520})11110100.{8}(.{464}).{1056}/$1$2/g;

#     $final - pack("B*", $_); #Conver data back to original binary fo
+rmat
#     $final = pack("B*", $block);  # this is wrong
     $final = pack("B*", substr($block,0,$blocksz)); # this should wor
+k

     print OUT "$final";

     $final = ''; # this is strictly unnecssary but does keep variable
+ clean
#     undef $final;

     $block01 = substr($block,-$blocksz);  # this moves the upper bloc
+k down 
}

$final = pack("B*", substr($block,-$blocksz)); # get final block
print OUT "$final";

close OUT;
close IN;
[download]

Update:

Corrected a couple lines in code

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