Destroy GStremaer playbin2 completely on pause

This is needed to avoid the application to stall inside GStreamer when
the network connection goes down. Another option would be to lower the
connection timeout (is it even possible?), but this works always and the
application is still very responsive.

cfm-controller.cc

@@ -61,6 +61,9 @@ getProperty<bool>(void* object, const gchar* name)
 
 CFMController::CFMController(QDeclarativeContext* context):
     _context(context),
+    _connection(NULL),
+    _playbin(NULL),
+    _statusText(""),
     _bufferFillRate(-1),
     _playPending(false),
     _connected(false)
@@ -73,10 +76,6 @@ CFMController::CFMController(QDeclarativeContext* context):
     }
     dbus_connection_setup_with_g_main(systembus, NULL);
 
-    if ((_playbin = gst_element_factory_make("playbin2", "playbin")) == NULL) {
-        qFatal("Could not create GStreamer playbin2 element");
-    }
-
     if ((_connection = con_ic_connection_new ()) == NULL) {
         qFatal("Coult not create ConIcConnection object");
     }
@@ -85,45 +84,72 @@ CFMController::CFMController(QDeclarativeContext* context):
                      G_CALLBACK(CFMController::handleConnectionEvent), this);
     ::setProperty(_connection, "automatic-connection-events", true);
 
-    g_signal_connect(gst_pipeline_get_bus(GST_PIPELINE(_playbin)), "message",
-                     G_CALLBACK(CFMController::handleGstMessage), this);
-
-    ::setProperty(_playbin, "uri", CUACFM_STREAM_URL);
-
     // Register the controller in the QML context.
     _context->setContextProperty("controller", this);
 }
 
 
+GstElement* CFMController::gstPipeline()
+{
+    if (!_playbin) {
+        if ((_playbin = gst_element_factory_make("playbin2", "playbin")) == NULL) {
+            qFatal("Could not create GStreamer playbin2 element");
+        }
+        g_signal_connect(gst_pipeline_get_bus(GST_PIPELINE(_playbin)), "message",
+                         G_CALLBACK(CFMController::handleGstMessage), this);
+        ::setProperty(_playbin, "uri", CUACFM_STREAM_URL);
+        qDebug("gstreamer: created playbin2 element");
+    }
+    return _playbin;
+}
+
+
+void CFMController::destroyGstPipeline()
+{
+    if (_playbin) {
+        gst_element_set_state(_playbin, GST_STATE_PAUSED);
+        gst_object_unref(_playbin);
+        _bufferFillRate = -1;
+        _playbin = NULL;
+        qDebug("gstreamer: destroyed playbin2 element");
+    }
+}
+
+
 CFMController::~CFMController()
 {
-    gst_object_unref(_playbin);
+    destroyGstPipeline();
     g_object_unref(_connection);
 }
 
 
 bool CFMController::isMuted() const
 {
-    return ::getProperty<bool>(_playbin, "mute");
+    return _playbin ? ::getProperty<bool>(_playbin, "mute") : false;
 }
 
 
 void CFMController::setMuted(bool muteValue)
 {
-    ::setProperty(_playbin, "mute", muteValue);
-    emit mutedStatusChanged(muteValue);
-    updateStatusText();
+    if (_playbin) {
+        ::setProperty(_playbin, "mute", muteValue);
+        emit mutedStatusChanged(muteValue);
+        updateStatusText();
+    }
 }
 
 
 bool CFMController::isPlaying() const
 {
-    GstState state;
-    GstState nextState;
+    if (!_playbin)
+        return false;
 
     if (_playPending)
         return false;
 
+    GstState state;
+    GstState nextState;
+
     gst_element_get_state(_playbin,
                           &state,
                           &nextState,
@@ -170,15 +196,14 @@ void CFMController::setPlaying(bool playingValue)
         else {
             qDebug("playback: network available -> playing");
             _playPending = false;
-            gst_element_set_state(_playbin, GST_STATE_PLAYING);
+            gst_element_set_state(gstPipeline(), GST_STATE_PLAYING);
             emit playingStatusChanged(true);
         }
     }
     else {
         qDebug("playback: stopped");
         _playPending = false;
-        gst_element_set_state(_playbin, GST_STATE_PAUSED);
-        // TODO Wait for GStreamer notifies about status being actually changed
+        destroyGstPipeline();
         emit playingStatusChanged(false);
     }
     updateStatusText();
@@ -187,7 +212,7 @@ void CFMController::setPlaying(bool playingValue)
 
 bool CFMController::isBuffering() const
 {
-    return _bufferFillRate >= 0 && _bufferFillRate < 100;
+    return _playbin && _bufferFillRate >= 0 && _bufferFillRate < 100;
 }
 
 
@@ -204,6 +229,7 @@ void CFMController::handleGstMessage(GstBus     *bus,
     CFMController *controller = (CFMController*) controllerptr;
 
     Q_ASSERT(controller);
+    Q_ASSERT(controller->_playbin);
     Q_UNUSED(bus);
 
     switch (GST_MESSAGE_TYPE(message)) {

cfm-controller.h

@@ -85,6 +85,8 @@ public slots:
     bool                 _connected;
 
     void updateStatusText();
+    GstElement* gstPipeline();
+    void destroyGstPipeline();
 
     static void handleGstMessage(GstBus*     bus,
                                  GstMessage* message,