An Example for GStreamer Dynamic Pad (Decodebin)

gst-dynamic-pad.c

#include <gst/gst.h>

static gboolean bus_call (G_GNUC_UNUSED GstBus *bus, GstMessage *msg, gpointer data)
{
  GMainLoop *loop = (GMainLoop *) data;

  switch (GST_MESSAGE_TYPE (msg)) {

  case GST_MESSAGE_EOS:
    g_print ("End of stream\n");
    g_main_loop_quit (loop);
    break;

  case GST_MESSAGE_ERROR: {
    gchar  *debug;
    GError *error;

    gst_message_parse_error (msg, &error, &debug);
    g_free (debug);

    g_printerr ("Error: %s\n", error->message);
    g_error_free (error);

    g_main_loop_quit (loop);
    break;
  }
  default:
    break;
  }

  return TRUE;
}

static void cb_new_pad (GstElement *element, GstPad *pad, gpointer data)
{
  gchar *name;
  GstElement *other = data;

  name = gst_pad_get_name (pad);
  g_print ("A new pad %s was created for %s\n", name, gst_element_get_name(element));
  g_free (name);

  g_print ("element %s will be linked to %s\n",
           gst_element_get_name(element),
           gst_element_get_name(other));
  gst_element_link(element, other);
}

gint main (gint   argc, gchar *argv[])
{
  GMainLoop *loop;
  GstElement *pipeline, *src, *dec, *conv, *sink;
  GstBus *bus;

  /* init GStreamer */
  gst_init (&argc, &argv);
  loop = g_main_loop_new (NULL, FALSE);

  /* setup */
  pipeline = gst_pipeline_new ("pipeline");

  bus = gst_pipeline_get_bus (GST_PIPELINE (pipeline));
  gst_bus_add_watch (bus, bus_call, loop);
  gst_object_unref (bus);

  src = gst_element_factory_make ("tcpserversrc", "src");
  g_object_set (G_OBJECT (src), "host", "127.0.0.1",NULL);
  g_object_set (G_OBJECT (src), "port", 5000 ,NULL);

  dec = gst_element_factory_make ("decodebin", "dec");
  conv = gst_element_factory_make ("audioconvert", "conv");
  sink = gst_element_factory_make ("alsasink", "sink");

  gst_bin_add_many (GST_BIN (pipeline), src, dec, conv, sink, NULL);

  gst_element_link (src, dec);
  gst_element_link (conv, sink);

  /* you don't link them here */
  /* gst_element_link (dec, conv); */
  /* add call-back, instead */
  g_signal_connect (dec, "pad-added", G_CALLBACK (cb_new_pad), conv);

  /* run */
  gst_element_set_state (pipeline, GST_STATE_PLAYING);
  g_main_loop_run (loop);

  /* cleanup */
  gst_element_set_state (pipeline, GST_STATE_NULL);
  gst_object_unref (GST_OBJECT (pipeline));

  return 0;
}

cb_new_pad function have memory leaks

Wow, thanks. gst_element_get_name()s in cb_new_pad() are "transfer_full". I'll fix it.