diff --git a/MediaPlayer.cpp b/MediaPlayer.cpp
index f4b8bd5..0b18c04 100644
--- a/MediaPlayer.cpp
+++ b/MediaPlayer.cpp
@@ -32,6 +32,7 @@ MediaPlayer::MediaPlayer(string name) : id_(name)
     pipeline_ = nullptr;
 
     ready_ = false;
+    failed_ = false;
     seeking_ = false;
     enabled_ = true;
     rate_ = 1.0;
@@ -77,8 +78,6 @@ static MediaInfo UriDiscoverer_(std::string uri)
 #endif
 
     MediaInfo video_stream_info;
-    // assume it will fail
-    video_stream_info.failed = true;
 
     /* Instantiate the Discoverer */
     GError *err = NULL;
@@ -118,15 +117,12 @@ static MediaInfo UriDiscoverer_(std::string uri)
         // no error, handle information found
         if ( result == GST_DISCOVERER_OK ) {
 
-            bool foundvideostream = false;
             GList *streams = gst_discoverer_info_get_video_streams(info);
             GList *tmp;
-            for (tmp = streams; tmp && !foundvideostream; tmp = tmp->next ) {
+            for (tmp = streams; tmp && !video_stream_info.valid; tmp = tmp->next ) {
                 GstDiscovererStreamInfo *tmpinf = (GstDiscovererStreamInfo *) tmp->data;
                 if ( GST_IS_DISCOVERER_VIDEO_INFO(tmpinf) )
                 {
-                    // inform that it succeeded
-                    video_stream_info.failed = false;
                     // found a video / image stream : fill-in information
                     GstDiscovererVideoInfo* vinfo = GST_DISCOVERER_VIDEO_INFO(tmpinf);
                     video_stream_info.width = gst_discoverer_video_info_get_width(vinfo);
@@ -161,16 +157,18 @@ static MediaInfo UriDiscoverer_(std::string uri)
                     const GstTagList *tags = gst_discoverer_stream_info_get_tags(tmpinf);
                     if ( tags ) {
                         gchar *container = NULL;
-                        gst_tag_list_get_string (tags, GST_TAG_CONTAINER_FORMAT, &container);
-                        if (container)  video_stream_info.codec_name += " " + std::string(container);
+                        if ( gst_tag_list_get_string (tags, GST_TAG_CONTAINER_FORMAT, &container) )
+                             video_stream_info.codec_name += " " + std::string(container);
+                        g_free(container);
                     }
                     // exit loop
-                    foundvideostream = true;
+                    // inform that it succeeded
+                    video_stream_info.valid = true;
                 }
             }
             gst_discoverer_stream_info_list_free(streams);
 
-            if (!foundvideostream) {
+            if (!video_stream_info.valid) {
                 Log::Warning("Warning: No video stream in '%s'", uri.c_str());
             }
         }
@@ -226,7 +224,7 @@ void MediaPlayer::execute_open()
     if (error != NULL) {
         Log::Warning("MediaPlayer %s Could not construct pipeline %s:\n%s", id_.c_str(), description.c_str(), error->message);
         g_clear_error (&error);
-        media_.failed = true;
+        failed_ = true;
         return;
     }
     g_object_set(G_OBJECT(pipeline_), "name", id_.c_str(), NULL);
@@ -237,7 +235,7 @@ void MediaPlayer::execute_open()
     GstCaps *caps = gst_caps_from_string(capstring.c_str());
     if (!gst_video_info_from_caps (&v_frame_video_info_, caps)) {
         Log::Warning("MediaPlayer %s Could not configure video frame info", id_.c_str());
-        media_.failed = true;
+        failed_ = true;
         return;
     }
 
@@ -281,7 +279,7 @@ void MediaPlayer::execute_open()
     } 
     else {
         Log::Warning("MediaPlayer %s Could not configure  sink", id_.c_str());
-        media_.failed = true;
+        failed_ = true;
         return;
     }
     gst_caps_unref (caps);
@@ -293,7 +291,7 @@ void MediaPlayer::execute_open()
     GstStateChangeReturn ret = gst_element_set_state (pipeline_, desired_state_);
     if (ret == GST_STATE_CHANGE_FAILURE) {
         Log::Warning("MediaPlayer %s Could not open '%s'", id_.c_str(), uri_.c_str());
-        media_.failed = true;
+        failed_ = true;
         return;
     }
 
@@ -320,7 +318,7 @@ bool MediaPlayer::isOpen() const
 
 bool MediaPlayer::failed() const
 {
-    return media_.failed;
+    return failed_;
 }
 
 void MediaPlayer::close()
@@ -419,7 +417,7 @@ void MediaPlayer::enable(bool on)
         GstStateChangeReturn ret = gst_element_set_state (pipeline_, requested_state);
         if (ret == GST_STATE_CHANGE_FAILURE) {
             Log::Warning("MediaPlayer %s Failed to enable", gst_element_get_name(pipeline_));
-            media_.failed = true;
+            failed_ = true;
         }
 
     }
@@ -465,7 +463,7 @@ void MediaPlayer::play(bool on)
     GstStateChangeReturn ret = gst_element_set_state (pipeline_, desired_state_);
     if (ret == GST_STATE_CHANGE_FAILURE) {
         Log::Warning("MediaPlayer %s Failed to play", gst_element_get_name(pipeline_));
-        media_.failed = true;
+        failed_ = true;
     }    
 #ifdef MEDIA_PLAYER_DEBUG
     else if (on)
@@ -660,7 +658,7 @@ void MediaPlayer::fill_texture(guint index)
 void MediaPlayer::update()
 {
     // discard
-    if (media_.failed)
+    if (failed_)
         return;
 
     // not ready yet
@@ -671,7 +669,7 @@ void MediaPlayer::update()
             // ok, discovering thread is finished ! Get the info
             media_ = discoverer_.get();
             // if its ok, open the media
-            if (!media_.failed)
+            if (media_.valid)
                 execute_open();
         }
         // wait next frame to display
diff --git a/MediaPlayer.h b/MediaPlayer.h
index 016334e..4a6061e 100644
--- a/MediaPlayer.h
+++ b/MediaPlayer.h
@@ -32,7 +32,7 @@ struct MediaInfo {
     bool isimage;
     bool interlaced;
     bool seekable;
-    bool failed;
+    bool valid;
 
     MediaInfo() {
         width = par_width = 640;
@@ -43,7 +43,7 @@ struct MediaInfo {
         isimage = false;
         interlaced = false;
         seekable = false;
-        failed = false;
+        valid = false;
     }
 
     inline MediaInfo& operator = (const MediaInfo& b)
@@ -56,7 +56,7 @@ struct MediaInfo {
             this->bitrate = b.bitrate;
             this->framerate = b.framerate;
             this->codec_name = b.codec_name;
-            this->failed = b.failed;
+            this->valid = b.valid;
             this->isimage = b.isimage;
             this->interlaced = b.interlaced;
             this->seekable = b.seekable;
@@ -253,6 +253,7 @@ private:
     GstElement *pipeline_;
     GstVideoInfo v_frame_video_info_;
     std::atomic<bool> ready_;
+    std::atomic<bool> failed_;
     bool seeking_;
     bool enabled_;
 
diff --git a/MediaSource.cpp b/MediaSource.cpp
index 27c4f63..6cdb34d 100644
--- a/MediaSource.cpp
+++ b/MediaSource.cpp
@@ -124,8 +124,7 @@ void MediaSource::update(float dt)
     Source::update(dt);
 
     // update video
-    if (active_)
-        mediaplayer_->update();
+    mediaplayer_->update();
 }
 
 void MediaSource::render()
diff --git a/Mixer.cpp b/Mixer.cpp
index 544c4be..38a365c 100644
--- a/Mixer.cpp
+++ b/Mixer.cpp
@@ -150,13 +150,14 @@ Mixer::Mixer() : session_(nullptr), back_session_(nullptr), current_view_(nullpt
 
 void Mixer::update()
 {
+    // sort-of garbage collector : just wait for 1 iteration
+    // before deleting the previous session: this way, the sources
+    // had time to end properly
     if (garbage_.size()>0) {
-
         delete garbage_.back();
         garbage_.pop_back();
     }
 
-
 #ifdef THREADED_LOADING
     // if there is a session importer pending
     if (!sessionImporters_.empty()) {
@@ -184,7 +185,7 @@ void Mixer::update()
     // if a change of session is requested
     if (sessionSwapRequested_) {
         sessionSwapRequested_ = false;
-        // successfully loading
+        // sanity check
         if ( back_session_ ) {
             // swap front and back sessions
             swap();
@@ -606,21 +607,6 @@ void Mixer::load(const std::string& filename)
         // Start async thread for loading the session
         // Will be obtained in the future in update()
         sessionLoaders_.emplace_back( std::async(std::launch::async, loadSession_, filename) );
-
-
-//        Session *se = new Session;
-
-//        sessionLoaders_.emplace_back(std::async(std::launch::async,
-//                                                [](Session *s, const std::string& filename){
-//                                         // actual loading of xml file
-//                                         SessionCreator creator( s );
-//                                         if (creator.load(filename)) {
-//                                             // loaded ok
-//                                             s->setFilename(filename);
-//                                         }
-//                                         return s;
-//                                     }, se, filename));
-
     }
 #else
     set( loadSession_(filename) );
@@ -653,12 +639,16 @@ void Mixer::open(const std::string& filename)
 
 void Mixer::import(const std::string& filename)
 {
+#ifdef THREADED_LOADING
     // import only one at a time
     if (sessionImporters_.empty()) {
         // Start async thread for loading the session
         // Will be obtained in the future in update()
         sessionImporters_.emplace_back( std::async(std::launch::async, loadSession_, filename) );
     }
+#else
+    merge( loadSession_(filename) );
+#endif
 }
 
 void Mixer::merge(Session *session)
@@ -671,7 +661,6 @@ void Mixer::merge(Session *session)
     // import every sources
     for ( Source *s = session->popSource(); s != nullptr; s = session->popSource())
         insertSource(s);
-
 }
 
 void Mixer::swap()
@@ -730,7 +719,6 @@ void Mixer::swap()
     update_time_ = GST_CLOCK_TIME_NONE;
 
     // delete back (former front session)
-//    delete back_session_;
     garbage_.push_back(back_session_);
     back_session_ = nullptr;
 
@@ -760,7 +748,6 @@ void Mixer::clear()
     // delete previous back session if needed
     if (back_session_)
         garbage_.push_back(back_session_);
-//        delete back_session_;
 
     // create empty session
     back_session_ = new Session;
@@ -781,7 +768,6 @@ void Mixer::set(Session *s)
     // delete previous back session if needed
     if (back_session_)
         garbage_.push_back(back_session_);
-//        delete back_session_;
 
     // set to new given session
     back_session_ = s;
diff --git a/Source.cpp b/Source.cpp
index ffd32a9..03fc0b7 100644
--- a/Source.cpp
+++ b/Source.cpp
@@ -135,7 +135,7 @@ Source::~Source()
 {
     // inform clones that they lost their origin
     for (auto it = clones_.begin(); it != clones_.end(); it++)
-        (*it)->unlink();
+        (*it)->detach();
     clones_.clear();
 
     // delete objects
@@ -406,7 +406,7 @@ CloneSource *Source::clone()
 CloneSource::CloneSource(Source *origin) : Source(), origin_(origin)
 {
     // create surface:
-    clonesurface_ = nullptr;
+    clonesurface_ = new Surface(renderingshader_);
 }
 
 CloneSource::~CloneSource()
@@ -415,8 +415,7 @@ CloneSource::~CloneSource()
         origin_->clones_.remove(this);
 
     // delete surface
-    if (clonesurface_)
-        delete clonesurface_;
+    delete clonesurface_;
 }
 
 CloneSource *CloneSource::clone()
@@ -438,7 +437,6 @@ void CloneSource::init()
     if (origin_ && origin_->ready()) {
 
         // get the texture index from framebuffer of view, apply it to the surface
-        clonesurface_ = new Surface(renderingshader_);
         clonesurface_->setTextureIndex( origin_->texture() );
 
         // create Frame buffer matching size of session
diff --git a/Source.h b/Source.h
index 3a2d5cf..e1e5fd1 100644
--- a/Source.h
+++ b/Source.h
@@ -45,10 +45,6 @@ public:
 
     // cloning mechanism
     virtual CloneSource *clone ();
-//    void unClone(CloneSource *clone);
-//    inline size_t numClones() const { return clones_.size(); }
-//    inline CloneList::iterator beginClones () { return clones_.begin(); }
-//    inline CloneList::iterator endClones () { return clones_.end(); }
 
     // Display mode
     typedef enum {
@@ -195,7 +191,7 @@ public:
     void accept (Visitor& v) override;
 
     CloneSource *clone() override;
-    inline void unlink() { origin_ = nullptr; }
+    inline void detach() { origin_ = nullptr; }
     inline Source *origin() const { return origin_; }
 
 protected: