Play with this, do you really need a 1-liner?

#!/usr/bin/perl
use strict;
use MIME::Base64 qw( encode_base64 );

#encode
open INFILE, '<', $ARGV[0];
binmode INFILE;
open OUTFILE, '>', $ARGV[1];
my $buf;
while ( read( INFILE, $buf, 4096 ) ) {
    print OUTFILE encode_base64($buf);
}

close OUTFILE;
close INFILE;

###################################################
#decode_base64.pl:
#!/usr/bin/perl
use strict;
use MIME::Base64 qw( decode_base64 );

open INFILE,  '<', $ARGV[0];
open OUTFILE, '>', $ARGV[1];
binmode OUTFILE;
my $buf;
while ( $buf = <INFILE> ) {
    print OUTFILE decode_base64($buf);
}

close OUTFILE;
close INFILE;
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