Gst::QueryDuration issue
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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. As a workaround I thought I'd cast the returned value to Glib::RefPtr<Gst::QueryDuration> but the compiler refuses to do so. 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. 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 [hidden email] http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel |
Re: Gst::QueryDuration issue
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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 > [hidden email] > http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel -- José _______________________________________________ gstreamer-devel mailing list [hidden email] http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel |
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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. I wish that create() method just returned Glib::RefPtr<Gst::QueryDuration> On Thu, Sep 6, 2012 at 10:50 PM, José Alburquerque <[hidden email]> wrote:
_______________________________________________ gstreamer-devel mailing list [hidden email] http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel |
Re: Gst::QueryDuration issue
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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 > <[hidden email]> 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 > > [hidden email] > > > http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel > > -- > José > > _______________________________________________ > gstreamer-devel mailing list > [hidden email] > http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel > > _______________________________________________ > gstreamer-devel mailing list > [hidden email] > http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel -- José _______________________________________________ gstreamer-devel mailing list [hidden email] http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel |
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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 <[hidden email]> wrote:
_______________________________________________ gstreamer-devel mailing list [hidden email] http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel |
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