- mb_detect_encoding: documentation ( source)
<?php
$test = 'BEGIN:VCARD
VERSION:2.1
N;ENCODING=QUOTED-PRINTABLE:Iksi=F1ski;Piotr
FN;ENCODING=QUOTED-PRINTABLE:Piotr Iksi=F1ski
EMAIL;PREF;INTERNET:piotr.iksinski@somedomain.com
X-GENDER:Male
REV:20080716T203548Z
END:VCARD
';
echo mb_detect_encoding($test, ['UTF-8', 'UTF-16']);