mp3 gstreamer test

#include <gst/gst.h>

#include <stdio.h>
#include <string.h>

#include <gst/app/gstappsink.h>

GMainLoop *loop;
GstElement *pipeline;
GstElement *uridecodebin;
GstElement *appsink;
GstPad *sinkpad;
GThread *loop_thread;

static gboolean _gst_on_bus_message (GstBus * bus, GstMessage * message, void * data)
{
    switch (GST_MESSAGE_TYPE (message))
    {
    case GST_MESSAGE_STATE_CHANGED:
    {
        gchar *name;
        GstState old_state, new_state;
        gst_message_parse_state_changed (message, &old_state, &new_state, NULL);
        name = gst_object_get_name (message->src);
        printf("state change: %d -> %d (object %s)\r\n", old_state, new_state, name);
        g_free (name);

        break;
    }
    case GST_MESSAGE_EOS:
    {
        printf("Finished playback\n");
        break;
     }
    case GST_MESSAGE_ERROR:
    {
        GError *err = NULL;
        gchar *dbg_info = NULL;

        gst_message_parse_error (message, &err, &dbg_info);
        printf("BUSMSG ERROR from element %s: %s\r\n", GST_OBJECT_NAME (message->src), err->message);
        printf("Debugging info: %s\r\n", (dbg_info) ? dbg_info : "none");
        g_error_free (err);
        g_free (dbg_info);

        break;
    }
    case GST_MESSAGE_BUFFERING:
        printf ("GST_MESSAGE_BUFFERING\r\n");
        break;
    default:
    printf ("other bus msg %d %s\r\n", GST_MESSAGE_TYPE (message), gst_message_type_get_name(GST_MESSAGE_TYPE (message)));
        break;
    }

    return TRUE;
}

static GstFlowReturn _gst_on_new_sample (GstElement * elt, void * data)
{
  GstSample *sample;
  printf ("on_new_sample\r\n");
  sample = gst_app_sink_pull_sample (GST_APP_SINK (elt));
  gst_sample_unref (sample);
  return GST_FLOW_OK;
}

static gboolean _gst_on_pad_added (GstElement *gstdecodebin, GstPad *pad, gpointer user_data)
{
    GstCaps *caps;
    gchar *caps_str;
    gst_object_ref (pad);

    caps = gst_pad_query_caps (pad, NULL);
    caps_str = gst_caps_to_string (caps);
    printf ("pad added, caps: %s\r\n", caps_str);
    g_free (caps_str);
    gst_caps_unref (caps);

    appsink = gst_element_factory_make ("appsink", NULL);
    gst_bin_add (GST_BIN(pipeline), appsink);

    g_signal_connect (appsink, "new-sample", G_CALLBACK (_gst_on_new_sample), NULL);
    g_object_set (G_OBJECT (appsink), "max-buffers", 1, "sync", FALSE, "emit-signals", TRUE, NULL);

    sinkpad = gst_element_get_compatible_pad (appsink, pad, NULL);
    if (gst_pad_link (pad,sinkpad) == GST_PAD_LINK_OK)
    {
        printf ("link src->sinkpad ok\r\n");
    }
    else
    {
        printf ("link src->sinkpad FAIL\r\n");
    }

    return TRUE;
}

static gpointer _gst_loop_thread_func (gpointer data)
{
    g_main_loop_run (loop);
    return NULL;
}

static void _gst_setup (char *uri)
{
    GstBus *bus;

    loop = g_main_loop_new (NULL, FALSE);
    loop_thread = g_thread_new ("myloop", _gst_loop_thread_func, NULL);
    pipeline = gst_pipeline_new ("mypipeline");
    uridecodebin = gst_element_factory_make ("uridecodebin", "myuridecodebin");

    gst_bin_add (GST_BIN(pipeline), uridecodebin);

    // If I create the appsink here, it works
    //appsink = gst_element_factory_make ("appsink", NULL);
    //gst_bin_add (GST_BIN(pipeline), appsink);

    bus = gst_element_get_bus (pipeline);
    gst_bus_add_watch (bus, (GstBusFunc) _gst_on_bus_message, NULL);
    gst_object_unref (bus);

    g_signal_connect (uridecodebin, "pad-added", G_CALLBACK (_gst_on_pad_added), NULL);
    g_object_set (G_OBJECT(uridecodebin), "uri", uri, NULL);
    g_object_set (G_OBJECT (uridecodebin), "caps", gst_caps_from_string ("audio/mpeg, mpegversion = (int) { 1, 2 };"), NULL);
}

int main (int argc, char *argv[])
{
  gst_init (&argc, &argv);
  _gst_setup (argv[1]);
  sleep (2);
  printf ("\r\ngoing to PAUSED now\r\n");
  gst_element_set_state (pipeline, GST_STATE_PAUSED);
  sleep (2);
  printf ("\r\ngoing to PLAYING now\r\n");
  gst_element_set_state (pipeline, GST_STATE_PLAYING);
  sleep(10000);

  return 0;
}