[maemo-developers] Please help with receiving video using Gstreamer in GTK Application

[From: Merrick Fonnesbeck]

Hello, please someone respond and help me, I have really had a hard time
debugging this issue and getting incoming streaming video to display in
my GTK windowed application, and I need someone's help.  I have built a
GTK application for my Nokia N810 that sends video from the camera to
another N810 device.  I am now trying to get a similar GTK application
built for the receiving side to accept and receive the incoming video
and play it in a GTK drawing area on my window.  I got the following
GStreamer command line application to run, but I'm having trouble
putting the pipeline elements together to get it to work in my windowed
application.  Here's the command line version that works:

	gst-launch udpsrc port=5434
caps=application/x-rtp,clock-rate=90000 ! rtph263depay ! hantro4100dec !
xvimagesink

The problem seems to exist in the caps and setting the clock-rate value.
When I compile it and run it on my N810 it fails to link the pipeline
elements with the gst_element_link_many( ) call, and when I comment out
the gst_element_link_filtered( ) call to link the caps to the filter and
screen sink the app complains with the following error:

   GLIB ERROR ** default - GST error: gstbasertpdepayload.c(265) :
gst_base_rtp_depayload_chain () :  no clock rate was specified, likely
incomplete input caps.

Any ideas or help would be appreciated.  Appended is my function that
creates the pipeline and sets up the elements.  Thanks.

MFonnesbeck

/*----------  Code -------*/
pipeline = gst_pipeline_new("test-camera");
	
input_udp = gst_element_factory_make("udpsrc", "input_udp");
g_object_set (G_OBJECT (input_udp), "port", 5434, NULL);
input_rtp = gst_element_factory_make("rtph263depay", "input_rtp");
input_decoder = gst_element_factory_make("hantro4100dec",
"input_decoder");
input_screen_queue = gst_element_factory_make("queue",
"input_screen_queue");
csp_filter = gst_element_factory_make("ffmpegcolorspace", "csp_filter");
input_screen_sink = gst_element_factory_make("xvimagesink",
"input_screen_sink");

if(!(pipeline && input_udp && csp_filter && input_rtp && input_decoder
&& input_screen_queue && input_screen_sink))
{
	g_critical("Couldn't create pipeline elements");
	return FALSE;
}

gst_bin_add_many(GST_BIN(pipeline), input_udp, input_rtp, input_decoder,
input_screen_queue, csp_filter, input_screen_sink, NULL);
caps = gst_caps_new_simple("application/x-rtp", "clock-rate",
G_TYPE_INT, 90000, NULL);

if(!gst_element_link_filtered(csp_filter, input_screen_sink, caps))
{
	return FALSE;
}
gst_caps_unref(caps);

if(!gst_element_link_many(input_udp, input_rtp, input_decoder,
input_screen_queue, csp_filter, input_screen_sink, NULL))
{
	return FALSE;
}	

gst_element_set_state(pipeline, GST_STATE_PLAYING);
/*----------  Code -------*/


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