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Hi, I’m trying to create a custom audio sink plugin for gstreamer using the Gst::AudioSink as a base class. For me this involves multiple learning curves as I’m new to gstreamer, gstreamermm and gobject. Also I have no background or real
interest in gtkmm as I’m not working on GUI code at present. I am trying to create a class along the lines of: class MyAudioSink: public Gst::AudioSink { public: explicit MyAudioSink(KantarAudioSink *gobj); virtual ~MyAudioSink(); static void class_init(Gst::ElementClass<MyAudioSink> *klass); virtual int write_vfunc(gpointer data, guint length) override; virtual void reset_vfunc(); }; I seem to missing some magic in the class_init() function that should link the base class functions to the virtual functions in MyAudioSink. In C we would do something like: GObjectClass *gobject_class = G_OBJECT_CLASS (klass); GstAudioSinkClass *audio_sink_class = GST_AUDIO_SINK_CLASS (klass); audio_sink_class->write = GST_DEBUG_FUNCPTR (myaudiosink_write); I don’t really grok the C++ binding to gobject. What is the equivalent for linking to the C++ virtual function hierarchy? I got the impression from Marcin’s video
https://gstconf.ubicast.tv/videos/gstreamermm-c-way-of-doing-gstreamer-based-applications/ that the virtual functions should be invoked automatically. I can create a half usable (doesn’t handle things like EOS) plugin by adding: add_pad(sinkpad = Gst::Pad::create(get_pad_template("sink"), "sink")); sinkpad->set_chain_function(sigc::mem_fun(*this, &MyAudioSink::chain)); But a sink should not have a chain function. Also it seems strange that I have to add the sink pad at all. An audio sink should already have one I should just need to refine the capabilities a bit more. I guess this is an artifact of using gmmproc to create C++ wrappers? I don’t want to use gmmproc myself (I not sure what package its in anyway). I think there should some example elements and more introductory documentation (this is something I may be able to help with as I do this other commitments permitting). The best example transform element I could find was the foo element
used in the test code. There is no equivalent for a sink element. It’s also worth mentioning that the generated documentation does not appear online here https://developer.gnome.org/gstreamermm/1.10/ Regards, Bruce. Kantar Disclaimer |