[gst-devel] element specific bus messages

[Tim Hilden]

well, the following code reads the bus messages:

gboolean bus_callback(GstBus *bus, GstMessage *message, gpointer
unused){
  printf("%s: %s\n", gst_object_get_name(message->src),\
	  gst_message_type_get_name(message->type));

  switch(GST_MESSAGE_TYPE(message)){
    case GST_MESSAGE_ERROR:{
      fprintf(stderr, "ERROR\n");
      g_main_loop_quit(loop);
      break;
    }
    case GST_MESSAGE_EOS:{
      printf("end-of-stream\n");
      g_main_loop_quit(loop);
      break;
    }
  }

  return true;
}

generates the following output :

demuxer: tag
videosink: element
videosink: element
videosink: state-changed

to me this shows that I rereived an element specific message from
element "videosink", which in this case is a xvimagesink.

now the doc for xvimagesink
http://gstreamer.freedesktop.org/data/doc/gstreamer/head/gst-plugins-base-plugins/html/gst-plugins-base-plugins-xvimagesink.html
doesn't tell me anything about a specific message (unlike the spectrum
element for example). And how am I supposed to make the connection from
xvimagesink to the GstXOverlay definition by just looking at the URL 3
lines up?


Tim

On Tue, 2009-01-20 at 10:16 -0800, Michael Smith wrote:
> On Tue, Jan 20, 2009 at 8:09 AM, Tim Hilden <tim.hilden at googlemail.com> wrote:
> > hi there,
> >
> > playing around with the (sparsly documented) Gstreamer a couple of
> > questions came to my mind.
> >
> > This one is about the element specific bus messages. Getting a message
> > of type GST_MESSAGE_ELEMENT I wonder where I can find the "specific
> > element's documentation" that is mentioned in the API doc. The online
> > doc of elements like xvimagesink or jpegenc don't contain any
> > information on what the element's bus messages contain. So where can I
> > find that information?
> 
> That would mean a) those elements don't have any element-specific
> messages, or b) they're missing documentation for any they might send.
> 
> In this case, they just don't have any element-specific messages
> (though xvimagesink will send a "prepare-xwindow-id" message - as
> documented in the GstXOverlay interface, which it implements.
> 
> Mike
> 
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