Can't work out parameter format for LibVLC functions

[Domarius]

I just need help understanding how to provide the right variable types, by referring to the Python API for LibVLC.

I'm using the vlc.py Python wrapper, and I can't work out what format the parameters need to be in when calling "libvlc_video_set_aspect_ratio".

vlc.libvlc_video_set_aspect_ratio(player, "16:9")
Gives the error;
ctypes.ArgumentError: argument 2: <class 'TypeError'>: wrong type

vlc.libvlc_video_set_aspect_ratio(player, c_char_p('16:9'))
Gives the error;
"builtins.TypeError: bytes or integer address expected instead of str instance"

Here is the documentation for libvlc_video_set_aspect_ratio:

def libvlc_video_set_aspect_ratio(p_mi, psz_aspect): 
    '''Set new video aspect ratio. 
    @param p_mi: the media player. 
    @param psz_aspect: new video aspect-ratio or None to reset to default @note Invalid aspect ratios are ignored. 
    ''' 
    f = _Cfunctions.get('libvlc_video_set_aspect_ratio', None) or \ 
        _Cfunction('libvlc_video_set_aspect_ratio', ((1,), (1,),), None, 
                    None, MediaPlayer, ctypes.c_char_p) 
    return f(p_mi, psz_aspect)