Please describe the problem:
the subparse element is unable to recode characters from any encoding into UTF-8 without the system package glib-gconv plus the correct charmap, like glibc-gconv-iso8859.

Steps to reproduce:
without glib-gconv present
1. gst-launch-0.10 filesrc location=subs.srt ! subparse
subtitle-encoding="ISO-8859-1" ! fakesink dump=true
2. export GST_SUBTITLE_ENCODING="ISO-8859-15"
3. gst-launch-0.10 filesrc location=subs.srt ! subparse ! fakesink dump=true

Actual results:
when a special character occurs in the text stream, playback stops with this debug info:
....
0:00:02.335854000  1465 0x10024890 INFO              subparse
gstsubparse.c:316:convert_encoding:<subparse0> invalid UTF-8!                   
0:00:02.337064000  1465 0x10024890 WARN              subparse
gstsubparse.c:337:convert_encoding:<subparse0> could not convert string from
'ISO-8859-15' to UTF-8: Conversion from character set 'ISO-8859-15' to 'UTF-8'
is not supported                                                      
....

Expected results:
i'd expect an error message that eases finding out the cause of the malfunction (missing glib-gconv and charmap).

Does this happen every time?


Other information:
This report derives from http://bugzilla.gnome.org/show_bug.cgi?id=555647#c8