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<http://www.kantar.com/disclaimer.html>
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