Glib::RefPtr<Gst::QueryCaps> ->set_caps_result gives error that "gst_mini_object_ref: assertion 'mini_object != NULL' failed"

[Ankur Deep Jaiswal <ankur techgentsia com>]

Hi,

i am trying to implement a gstreamermm plugin for a H264 hardware encoder using gstreamermm.

i am extending Gst::PushSrc for this. 

listening to Query Events using

this->get_src_pad()->set_query_function(sigc::mem_fun(*this, &FooSrc::query_event));

i am processing the query events as specified below

gboolean query_event(const Glib::RefPtr<Gst::Pad>& pad, Glib::RefPtr<Gst::Query>& queryevent)

    {

      std::cout << "got a query event: " << pad->get_name() << ":" << queryevent->get_query_type() << std::endl;

      switch (queryevent->get_query_type())

      {

        case Gst::QueryType::QUERY_CAPS:

        {

          Glib::RefPtr<Gst::QueryCaps> querycaps = Glib::RefPtr<Gst::QueryCaps>::cast_static(queryevent);

          auto newquerycaps = Glib::RefPtr<Gst::QueryCaps>::cast_static(querycaps->create_writable());

          auto caps = Gst::Caps::create_from_string(

              "video/x-h264, stream-format=(string)byte-stream, alignment=(string)au");

          newquerycaps->set_caps_result(caps);

          return true;

        }

      }

      return false;

    }

but after the function has executed i get hit by the following error.

GStreamer-CRITICAL **: 20:04:41.081: gst_mini_object_ref: assertion 'mini_object != NULL' failed

to over come this, if we use the c interface for the above code , everything works perfectly fine.

    gboolean query_event(const Glib::RefPtr<Gst::Pad>& pad, Glib::RefPtr<Gst::Query>& queryevent)

    {

      std::cout << "got a query event: " << pad->get_name() << ":" << queryevent->get_query_type() << std::endl;

      switch (queryevent->get_query_type())

      {

        case Gst::QueryType::QUERY_CAPS:

        {

           std::cout << "Gst Query Event  is writable:" << queryevent->is_writable() << std::endl;

           auto * q = queryevent->gobj();

           std::cout << "Gst Query is writable: " << gst_query_is_writable(q) << std::endl;

           auto * wq = gst_query_make_writable(q);

           auto * newcaps = gst_caps_new_simple("video/x-h264",

           "stream-format",G_TYPE_STRING,"byte-stream",

           "alignment",G_TYPE_STRING,"au",

           NULL);

           gst_query_set_caps_result(wq, newcaps);

           std::cout << "Gst Query is written : " << std::endl;

           gst_caps_unref (newcaps);

          return true;

        }

      }

      return false;

    }

please do suggest.

--

Regards

Ankur Deep Jaiswal
Software Architect
Techgentsia Software Technologies Private Limited
Ernakulam