I am not sure about your input (you should use the <code> tags). But if you mean something like this, then it's easy.
The "$/" variable holds the separator. Changing it to a double return, will parse what you want.

#!/usr/bin/perl -w
use strict;
my @array =();
{
        local $/="\n\n";
        push @array, $_ while <DATA>
}

print join (",", split( /\n/, $_)),"\n" for (@array) ;

__DATA__
a
b
c

d
e
f
[download]

Each "record" in the array is a group of three lines, which you can then separate using the split function.