Sets the datetime pointed to by value corresponding to the datetime of the
given field. Caller is responsible for making sure the field exists
and has the correct type.
On success value will point to a reference of the datetime which
should be unreffed with gst_date_time_unref() when no longer needed
(note: this is inconsistent with e.g. gst_structure_get_string()
which doesn't return a copy of the string).
TRUE if the value could be set correctly. If there was no field with fieldname or the existing field did not contain a data, this function returns FALSE.
Sets the datetime pointed to by value corresponding to the datetime of the given field. Caller is responsible for making sure the field exists and has the correct type. On success value will point to a reference of the datetime which should be unreffed with gst_date_time_unref() when no longer needed (note: this is inconsistent with e.g. gst_structure_get_string() which doesn't return a copy of the string).