Gst::QueryDuration issue

[Jiergir Ogoerg]

Thanks for your efforts,
I submitted the bug here:
https://bugzilla.gnome.org/show_bug.cgi?id=683580


On Fri, Sep 7, 2012 at 3:03 PM, José Alburquerque <jaalburquerque at cox.net>wrote:

> On Fri, 2012-09-07 at 07:20 +0300, Jiergir Ogoerg wrote:
> > Thanks,
> > your cast works!
> >
> > The code I'm talking about which doesn't compile is at the bottom
> > of this screenshot:
> > http://f35f22fan.blogspot.com/2012/09/gstreamer.html
> >
> > 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.
>
> Ah, that's a beginner's attempt at a crude C++ translation of the usage
> example found in GstQuery's description section.  It was placed in the
> Gst::Query class docs as an attempt to also show how the class could be
> used.  I guess little thought was put into the need to cast correctly
> before using the parse() method as you describe.
>
> The line which should cast has been fixed in this commit:
>
> http://git.gnome.org/browse/gstreamermm/commit/?id=a6933d2012fbe626eb110320ab6c4338c583e7bc
>
> Please feel free to report any errors you find here:
> https://bugzilla.gnome.org/enter_bug.cgi?product=gstreamermm
>
> >
> > I wish that create() method just returned
> > Glib::RefPtr<Gst::QueryDuration>
> >
> Feel free to file a bug about that also.
>
> >
> > On Thu, Sep 6, 2012 at 10:50 PM, José Alburquerque
> > <jaalburquerque at cox.net> wrote:
> >         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.
> >
> >
> >         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.
> >         >
> >         > As a workaround I thought I'd cast the returned value to
> >         > Glib::RefPtr<Gst::QueryDuration> but the compiler refuses to
> >         do so.
> >
> >
> >         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.
> >         >
> >         > 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.
> >
> >
> >         Really?  What example would that be?  The gstreamermm examples
> >         should
> >         compile and work fine with gstreamermm.
> >         >
> >         > 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?
> >
> >         > _______________________________________________
> >         > gstreamer-devel mailing list
> >         > gstreamer-devel at lists.freedesktop.org
> >         >
> >         http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
> >
> >         --
> >         José
> >
> >         _______________________________________________
> >         gstreamer-devel mailing list
> >         gstreamer-devel at lists.freedesktop.org
> >         http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
> >
> > _______________________________________________
> > gstreamer-devel mailing list
> > gstreamer-devel at lists.freedesktop.org
> > http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel
>
> --
> José
>
> _______________________________________________
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>
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