[gstreamer-bugs] [Bug 512382] New: race condition when pausing/playing multiple elements

[GStreamer (bugzilla.gnome.org)]

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  GStreamer | don't know | Ver: 0.10.16
           Summary: race condition when pausing/playing multiple elements
           Product: GStreamer
           Version: 0.10.16
          Platform: Other
        OS/Version: All
            Status: UNCONFIRMED
          Severity: normal
          Priority: Normal
         Component: don't know
        AssignedTo: gstreamer-bugs at lists.sourceforge.net
        ReportedBy: marcus.brinkmann at ruhr-uni-bochum.de
         QAContact: gstreamer-bugs at lists.sourceforge.net
     GNOME version: 2.19/2.20
   GNOME milestone: Unspecified


Please describe the problem:
When I create multiple playbin elements in the paused or ready state quickly
after each other, things get pretty messed up.  Most of the time, only one of
the files actually can be heard (the other seems to "play" silently), but once
in a while I get random assertion failues, crashes, etc.

If there is a one second pause between the individual element's creation and
setup, all files can be heard playing.

Steps to reproduce:
Run the following example program, for example with two file:///file1.ogg and
file:///file2.ogg.
#include <gst/gst.h>
GMainLoop *loop;
static gboolean
my_bus_callback (GstBus *bus, GstMessage *message, gpointer data)
{
  switch (GST_MESSAGE_TYPE (message))
    {
    case GST_MESSAGE_ERROR:
      {
        GError *err;
        gchar *debug;

        gst_message_parse_error (message, &err, &debug);
        g_print ("Error: %s\n", err->message);
        g_error_free (err);
        g_free (debug);

        g_main_quit (loop);
        break;
      }

    case GST_MESSAGE_EOS:
      /* end-of-stream */
      g_main_quit (loop);
      break;

    default:
      /* unhandled message */
      break;
  }

  /* We want to be notified again the next time there is a message on
     the bus, so returning TRUE (FALSE means we want to stop watching
     for messages on the bus and our callback should not be called
     again).  */
  return TRUE;
}

int
main (int argc, char *argv[])
{
  gst_init (&argc, &argv);

  loop = g_main_loop_new (NULL, FALSE);

  argc--;
  argv++;
  while (argc-- > 0)
    {
      GstElement *play;
      GstBus *bus;

      play = gst_element_factory_make ("playbin", "play");
      g_object_set (G_OBJECT (play), "uri", argv[0], NULL);
      argv++;

      bus = gst_pipeline_get_bus (GST_PIPELINE (play));
      gst_bus_add_watch (bus, my_bus_callback, loop);
      gst_object_unref (bus);

      gst_element_set_state (play, GST_STATE_PLAYING);
      // Sleep works around it.
      // sleep (1);
    }

  g_main_loop_run (loop);

  return 0;
}


Actual results:
Most of the time, only one file is heard from the speaker.  Sometimes, various
random crashes and assertion failures occur, for example:

* main3: pcm.c:725: snd_pcm_nonblock: Assertion `pcm' failed.

* (main3:16472): GLib-GObject-WARNING **: invalid (NULL) pointer instance

(main3:16472): GLib-GObject-CRITICAL **: g_signal_connect_data: assertion
`G_TYPE_CHECK_INSTANCE (instance)' failed

(main3:16472): GLib-GObject-CRITICAL **: g_object_set_data: assertion
`G_IS_OBJECT (object)' failed

(main3:16472): GStreamer-CRITICAL **: gst_pad_link_prepare: assertion
`GST_IS_PAD (sinkpad)' failed

(main3:16472): GStreamer-CRITICAL **: gst_object_unref: assertion `object !=
NULL' failed
Error: Internal data stream error.

* (main3:17385): GLib-GObject-WARNING **: IA__g_object_set_valist: object class
`GstStreamInfo' has no property named `mute'


Expected results:
What should happen is that both files start playing and are heard.

Does this happen every time?
Yes.

Other information:
sleep(1) after changing the state to PLAYING works around it.


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