[RE] Newbie question: Basic Tutorial #3 (Dynamic Pipelines)

[김태수]

Hello.

You don't need to use "tee".

There will be 2 pads (one for audio and the other for video) from "uridecodebin" and,

each pad should be linked to each proper converter.

Below is my modified source code with video ouput.

#include <gst/gst.h>

/* Structure to contain all our information, so we can pass it to
callbacks */
typedef struct _CustomData {
 GstElement *pipeline;
 GstElement *source;
 GstElement *vconvert;
 GstElement *vsink;
 GstElement *convert;
 GstElement *sink;
} CustomData;

/* Handler for the pad-added signal */
static void pad_added_handler(GstElement *src, GstPad *pad, CustomData
 *data);

int main(int argc, char *argv[]) {
 CustomData data;
 GstBus *bus;
 GstMessage *msg;
 GstStateChangeReturn ret;
 gboolean terminate = FALSE;

 /* Initialize GStreamer */
 gst_init(NULL, NULL);

 /* Create the elements */
 data.source = gst_element_factory_make("uridecodebin", "source");
 data.vconvert = gst_element_factory_make("videoconvert", "vconvert");
 data.vsink = gst_element_factory_make("autovideosink", "vsink");
 data.convert = gst_element_factory_make("audioconvert", "convert");
 data.sink = gst_element_factory_make("autoaudiosink", "sink");

 /* Create the empty pipeline */
 data.pipeline = gst_pipeline_new("test-pipeline");

 if (!data.pipeline || !data.source || !data.vconvert || !data.vsink
  || !data.convert || !data.sink) {
  g_printerr("Not all elements could be created.\n");
  return -1;
 }

 /* Build the pipeline. Note that we are NOT linking the source at this
 * point. We will do it later. */
 gst_bin_add_many(GST_BIN(data.pipeline), data.source, data.vconvert,
  data.vsink, data.convert, data.sink, NULL);
 if (!gst_element_link(data.vconvert, data.vsink)) {
  g_printerr("Elements could not be linked.\n");
  gst_object_unref(data.pipeline);
  return -1;
 }

 if (!gst_element_link(data.convert, data.sink)) {
  g_printerr("Elements could not be linked.\n");
  gst_object_unref(data.pipeline);
  return -1;
 }

 /* Set the URI to play */
 g_object_set(data.source, "uri",
  "http://docs.gstreamer.com/media/sintel_trailer-480p.webm", NULL);

 /* Connect to the pad-added signal */
 g_signal_connect(data.source, "pad-added", G_CALLBACK
  (pad_added_handler), &data);

 /* Start playing */
 ret = gst_element_set_state(data.pipeline, GST_STATE_PLAYING);
 if (ret == GST_STATE_CHANGE_FAILURE) {
  g_printerr("Unable to set the pipeline to the playing state.\n");
  gst_object_unref(data.pipeline);
  return -1;
 }

 /* Listen to the bus */
 bus = gst_element_get_bus(data.pipeline);
 do {
  msg = gst_bus_timed_pop_filtered(bus, GST_CLOCK_TIME_NONE,
   (GstMessageType)(GST_MESSAGE_STATE_CHANGED | GST_MESSAGE_ERROR | GST_MESSAGE_EOS));

  /* Parse message */
  if (msg != NULL) {
   GError *err;
   gchar *debug_info;

   switch (GST_MESSAGE_TYPE(msg)) {
   case GST_MESSAGE_ERROR:
    gst_message_parse_error(msg, &err, &debug_info);
    g_printerr("Error received from element %s: %s\n",
     GST_OBJECT_NAME(msg->src), err->message);
    g_printerr("Debugging information: %s\n", debug_info ?
    debug_info : "none");
    g_clear_error(&err);
    g_free(debug_info);
    terminate = TRUE;
    break;
   case GST_MESSAGE_EOS:
    g_print("End-Of-Stream reached.\n");
    terminate = TRUE;
    break;
   case GST_MESSAGE_STATE_CHANGED:
    /* We are only interested in state-changed messages from the
    pipeline */
    if (GST_MESSAGE_SRC(msg) == GST_OBJECT(data.pipeline)) {
     GstState old_state, new_state, pending_state;
     gst_message_parse_state_changed(msg, &old_state,
      &new_state, &pending_state);
     g_print("Pipeline state changed from %s to %s:\n",
      gst_element_state_get_name(old_state),
      gst_element_state_get_name(new_state));
    }
    break;
   default:
    /* We should not reach here */
    g_printerr("Unexpected message received.\n");
    break;
   }
   gst_message_unref(msg);
  }
 } while (!terminate);

 /* Free resources */
 gst_object_unref(bus);
 gst_element_set_state(data.pipeline, GST_STATE_NULL);
 gst_object_unref(data.pipeline);
 return 0;
}

/* This function will be called by the pad-added signal */
static void pad_added_handler(GstElement *src, GstPad *new_pad,
 CustomData *data) {
 GstPad *sink_pad = NULL;
 GstPadLinkReturn ret;
 GstCaps *new_pad_caps = NULL;
 GstStructure *new_pad_struct = NULL;
 const gchar *new_pad_type = NULL;

 g_print("Received new pad '%s' from '%s':\n", GST_PAD_NAME
  (new_pad), GST_ELEMENT_NAME(src));

 /* If our converter is already linked, we have nothing to do here */
 if (gst_pad_is_linked(sink_pad)) {
  g_print("  We are already linked. Ignoring.\n");
  goto exit;
 }

 /* Check the new pad's type */
 new_pad_caps = gst_pad_get_current_caps(new_pad);
 new_pad_struct = gst_caps_get_structure(new_pad_caps, 0);
 new_pad_type = gst_structure_get_name(new_pad_struct);
 if (g_str_has_prefix(new_pad_type, "audio/x-raw")) {
  sink_pad = gst_element_get_static_pad(data->convert, "sink");
 }
 else if (g_str_has_prefix(new_pad_type, "video/x-raw")) {
  sink_pad = gst_element_get_static_pad(data->vconvert, "sink");
 }

 /* Attempt the link */
 ret = gst_pad_link(new_pad, sink_pad);
 if (GST_PAD_LINK_FAILED(ret)) {
  g_print("  Type is '%s' but link failed.\n", new_pad_type);
 }
 else {
  g_print("  Link succeeded (type '%s').\n", new_pad_type);
 }

exit:
 /* Unreference the new pad's caps, if we got them */
 if (new_pad_caps != NULL)
  gst_caps_unref(new_pad_caps);

 /* Unreference the sink pad */
 gst_object_unref(sink_pad);
}

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