Generally Text::CSV is the right way to handle CSV files, not sure what exactly you don't like about it. Here's the example: 

use strict;
use warnings;
use Text::CSV;
use MIME::Base64;

my $csv = Text::CSV->new( { binary => 1, eol => "\n" } );

while ( my $row = $csv->getline( \*DATA ) ) {
    for (@$row) {
        $_ = decode_base64($_) if m{
            ^
            (?: [A-Za-z0-9+/]{4} )*
            (?:
                [A-Za-z0-9+/]{2} [AEIMQUYcgkosw048] =
            |
                [A-Za-z0-9+/] [AQgw] ==
            )?
            $
        }x;
    }
    $csv->print( \*STDOUT, $row );
}
__DATA__
1,Just some data,c29tZSBzdHJpbmc=
2,VGhlIG5leHQgY29sdW1uIGlzIG5vdCBhY3R1YWxseSBCYXNlNjQgZW5jb2RlZA==,Oop
+s

[download]

Note, that "Oops" is a valid Base64, so you can't always distinct between string and Base64 encoded data.

In reply to Re: Searching for Base64 by zwon
in thread Searching for Base64 by horsechoker

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.