Thanks, your cast works! The code I'm talking about which doesn't compile is at the bottom of this screenshot: <a href="http://f35f22fan.blogspot.com/2012/09/gstreamer.html">http://f35f22fan.blogspot.com/2012/09/gstreamer.html</a> As one can see 1) The guy who wrote it calls "parse()" on a Gst::Query object 2) He uses "." to refer to the "parse()" method instead of "->" So clearly it wouldn't compile, so I didn't even try. I wish that create() method just returned Glib::RefPtr<Gst::QueryDuration> <div class="gmail_quote">On Thu, Sep 6, 2012 at 10:50 PM, José Alburquerque <<a href="mailto:jaalburquerque@cox.net" target="_blank">jaalburquerque@cox.net</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="im">On Thu, 2012-09-06 at 19:14 +0300, Jiergir Ogoerg wrote: > Hi, > I'm using the C++ backend of gstreamer (0.10) > > The problem is that Gst::QueryDuration::create(Format format) returns > Glib::RefPtr<Gst::Query> instead of Glib::RefPtr<Gst::QueryDuration> > which makes it impossible to use the parse() method of the returned > object since parse() only exists in Gst::QueryDuration. </div>The create() methods of the Gst::Query* classes wrap the gst_query_new_*() functions and they return a GstQuery so the create() methods similarly return a Gst::Query. <div class="im">> > As a workaround I thought I'd cast the returned value to > Glib::RefPtr<Gst::QueryDuration> but the compiler refuses to do so. </div>The proper way to cast it would be something like: Glib::RefPtr<Gst::QueryDuration> durQuery = Glib::RefPtr<Gst::QueryDuration>::cast_dynamic(query); The ogg_player, ogg_player_gtkmm and the media_player_gtkmm examples show how this is done when querying the pipeline for the position of the stream. <div class="im">> > Using Ubuntu 12.04 amd64, the documentation (libgstreamermm-0.10-doc) > doesn't tell how to do it. > > However, in Ubuntu 12.10 (yet to be released), the documentation is > updated with an example but it doesn't compile because the example > calls parse() on a Gst::Query object which doesn't have such a method. </div>Really? What example would that be? The gstreamermm examples should compile and work fine with gstreamermm. <div class="im">> > So how do I create a Gst::QueryDuration object to be able to call > parse() to get the duration? Is it a broken C++ bindings design? </div>> _______________________________________________ > gstreamer-devel mailing list > <a href="mailto:gstreamer-devel@lists.freedesktop.org">gstreamer-devel@lists.freedesktop.org</a> > <a href="http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel" target="_blank">http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel</a> -- José _______________________________________________ gstreamer-devel mailing list <a href="mailto:gstreamer-devel@lists.freedesktop.org">gstreamer-devel@lists.freedesktop.org</a> <a href="http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel" target="_blank">http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel</a> </blockquote></div>