Hi, use gst-inspect rstpsrc. You will see that the rstpsrc pad is a sometimes pad, so it can not be linked at the beginning. You need a add pad callback to link your rstpsrc and queue. You should also test the return function, it can help to debug, (see gst_element_link_many for example). <div>2007/5/10, 聂巍 <<a href="mailto:kanzakiv@gmail.com">kanzakiv@gmail.com</a>>:<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> Hi all I am writing a demo to act as the following command linegst-launch rtspsrc location = " rtsp://192.168.1.100/1.mp3" ! queue ! fakesink but when I compiled and ran the following helloworld.c[root@localhost / ] # helloworld rtsp://192.168.1.100/1.mp3 it says """"""""""""""""""""""" ERROR: from element /pipeline/rtp_disk_source/udpsrc2: Internal data flow error. Additional debug info: gstbasesrc.c(1614): gst_base_src_loop (): /pipeline/rtp_disk_source/udpsrc2: streaming task paused, reason not-linked (-1) """"""""""""""""""""""" the gst-launch command line works just fine, but I don't know why the demo can't do itdoes anybody know this ?thank you very much ------------------------------------------------------------ //  helloworld.c #include <stdlib.h> #include <gst/gst.h> static void event_loop (GstElement * pipe) {   GstBus *bus;   GstMessage *message = NULL;   bus = gst_element_get_bus (GST_ELEMENT (pipe));   while (TRUE) {     message = gst_bus_poll (bus, GST_MESSAGE_ANY, -1);     g_assert (message != NULL);     switch (message->type) {       case GST_MESSAGE_EOS:         gst_message_unref (message);         return;       case GST_MESSAGE_WARNING:       case GST_MESSAGE_ERROR:{         GError *gerror;         gchar *debug;         gst_message_parse_error (message, &gerror, &debug);         gst_object_default_error (GST_MESSAGE_SRC (message), gerror, debug);         gst_message_unref (message);         g_error_free (gerror);         g_free (debug);         return;       }       default:         gst_message_unref (message);         break;     }   } } int main (int argc, char *argv[]) {   GstElement *bin, *filesrc , *fakesink, *queue;     gst_init (&argc, &argv);   if (argc != 2) {     g_print ("usage: %s <rtsp mp3 file>\n", argv[0]);     exit (-1);   }   /* create a new bin to hold the elements */   bin = gst_pipeline_new ("pipeline");   g_assert (bin);   /* create a disk reader */   filesrc = gst_element_factory_make ("rtspsrc", "rtp_disk_source");   if(!filesrc)    {         printf("could not create \"rtspsrc\" element!");                return -1;    }   g_object_set (G_OBJECT (filesrc), "location", argv[1] , NULL);   printf("argv[1] is %s\n",argv[1]);   /* and an audio sink */   fakesink = gst_element_factory_make ("fakesink","fake_sink");   queue = gst_element_factory_make ("queue","queue");   /* add objects to the main pipeline */   gst_bin_add_many (GST_BIN (bin),filesrc, queue, fakesink,NULL);   /* link the elements */   gst_element_link_many (filesrc, queue, fakesink,NULL);     /* start playing */   gst_element_set_state (bin, GST_STATE_PLAYING);   /* Run event loop listening for bus messages until EOS or ERROR */   event_loop (bin);   /* stop the bin */   gst_element_set_state (bin, GST_STATE_NULL);   exit (0); } ERROR: from element /pipeline/rtp_disk_source/udpsrc2: Internal data flow error. Additional debug info: gstbasesrc.c(1614): gst_base_src_loop (): /pipeline/rtp_disk_source/udpsrc2: streaming task paused, reason not-linked (-1) ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. <a onclick="return top.js.OpenExtLink(window,event,this)" href="http://sourceforge.net/powerbar/db2/" target="_blank">http://sourceforge.net/powerbar/db2/</a> _______________________________________________ gstreamer-devel mailing list <a onclick="return top.js.OpenExtLink(window,event,this)" href="mailto:gstreamer-devel@lists.sourceforge.net">gstreamer-devel@lists.sourceforge.net</a> <a onclick="return top.js.OpenExtLink(window,event,this)" href="https://lists.sourceforge.net/lists/listinfo/gstreamer-devel" target="_blank"> https://lists.sourceforge.net/lists/listinfo/gstreamer-devel</a> </blockquote></div>