[FriBidi] what encoding? Where are the docs?

[Thurn, Martin]

Hello,
  I'm looking forward to using fribidi, via the FriBidi perl module.  I
can not find any documentation that tells what encoding the input data
is supposed to be.   I think I'm sending UTF-8, but it's not working (I
get the same text back out).  
  The only API documentation I can find is the README, which describes
only ONE function (fribidi_log2vis) and it doesn't tell what the
encoding is supposed to be.  
  Thank you for your time.
 - - Martin