#!/usr/bin/perl
use strict;
use warnings;
use Encode;

my $from     = $ARGV[0];
my $to       = $ARGV[1];
my $in_file  = $ARGV[2];
my $out_file = $ARGV[3];

open my $input, "<", $in_file or die "$!";
open my $output, ">", $out_file or die "$!";

local $/ = undef;

my($raw_octets,$perl_scalar,$utf8_octets);
while($raw_octets = <$input>){
    $perl_scalar = decode($from, $raw_octets);
    $utf8_octets = encode($to, $perl_scalar);
    print $output $utf8_octets;
}

close($input);
close($output);