Some attemps to resolve a graphic bug when changing position

src/LibVLCpp/VLCMediaPlayer.cpp

@@ -90,6 +90,7 @@ void                            MediaPlayer::callbacks( const libvlc_event_t* ev
         self->emit timeChanged();
         break;
     case libvlc_MediaPlayerPositionChanged:
+//        qDebug() << "Position changed" << event->u.media_player_position_changed.new_position;
         self->emit positionChanged();
         break;
 //TODO: activate this when switching to VLC 1.1

src/Workflow/ClipWorkflow.cpp

@@ -56,9 +56,14 @@ ClipWorkflow::~ClipWorkflow()
 
 unsigned char*    ClipWorkflow::getOutput()
 {
+//    qDebug() << "Getting output";
     QReadLocker     lock( m_backBufferLock );
     if ( m_usingBackBuffer == true )
+    {
+//        qDebug() << "Returning frontbuffer";
         return m_buffer;
+    }
+//    qDebug() << "Returning backbuffer";
     return m_backBuffer;
 }
 
@@ -68,25 +73,31 @@ void    ClipWorkflow::checkStateChange()
     QWriteLocker    lock2( m_stateLock );
     if ( m_requiredState != ClipWorkflow::None )
     {
-        qDebug() << "Setting required state : " << m_requiredState;
         m_state = m_requiredState;
         m_requiredState = ClipWorkflow::None;
     }
 }
 
-void    ClipWorkflow::lock( ClipWorkflow* clipWorkflow, void** pp_ret )
+void    ClipWorkflow::lock( ClipWorkflow* cw, void** pp_ret )
 {
 //    qDebug() << "Locking in ClipWorkflow::lock";
-    QReadLocker     lock( clipWorkflow->m_backBufferLock );
+    QReadLocker lock( cw->m_backBufferLock );
 
-    if ( clipWorkflow->m_usingBackBuffer )
-        *pp_ret = clipWorkflow->m_backBuffer;
+    if ( cw->m_usingBackBuffer )
+    {
+//        qDebug() << "Using backbuffer";
+        *pp_ret = cw->m_backBuffer;
+    }
     else
-        *pp_ret = clipWorkflow->m_buffer;
+    {
+//        qDebug() << "Using frontbuffer";
+        *pp_ret = cw->m_buffer;
+    }
 }
 
 void    ClipWorkflow::unlock( ClipWorkflow* cw )
 {
+//    qDebug() << "UnLocking in ClipWorkflow::unlock";
     cw->m_stateLock->lockForWrite();
 
     if ( cw->m_state == Rendering )
@@ -94,21 +105,21 @@ void    ClipWorkflow::unlock( ClipWorkflow* cw )
         cw->m_state = Sleeping;
         cw->m_stateLock->unlock();
 
+//        qDebug() << "Sleeping....";
         QMutexLocker    lock( cw->m_condMutex );
         cw->m_waitCond->wait( cw->m_condMutex );
-
+        cw->m_stateLock->lockForWrite();
+        cw->m_state = Rendering;
+//        qDebug() << "Waiking";
         {
             QWriteLocker    lock2( cw->m_backBufferLock );
             cw->m_usingBackBuffer = !cw->m_usingBackBuffer;
         }
-
-        cw->m_stateLock->lockForWrite();
-        cw->m_state = Rendering;
     }
+    else
+        qDebug() << cw->m_state;
     cw->m_stateLock->unlock();
     cw->checkStateChange();
-
-//    qDebug() << "UnLocking in ClipWorkflow::unlock";
 }
 
 void    ClipWorkflow::setVmem()

src/Workflow/TrackWorkflow.cpp

@@ -87,12 +87,16 @@ unsigned char*      TrackWorkflow::renderClip( ClipWorkflow* cw, bool needReposi
     if ( cw->getState() == ClipWorkflow::Sleeping )
     {
         cw->getStateLock()->unlock();
-        ret = cw->getOutput();
         if ( needRepositioning == true )
         {
             cw->setPosition( pos );
         }
+        ret = cw->getOutput();
+//        qDebug() << "Waking renderer";
         cw->wake();
+//        qDebug() << "Awaken renderer";
+        //FIXME: sometimes, the renderer isn't awake soon enough, and we can
+        //pass though this function many times before the frame is actually rendered.
     }
     else if ( cw->getState() == ClipWorkflow::Stopped )
     {
@@ -110,7 +114,7 @@ unsigned char*      TrackWorkflow::renderClip( ClipWorkflow* cw, bool needReposi
     }
     else
     {
-        qDebug() << "Unexpected ClipWorkflow::State when rendering:" << cw->getState();
+//        qDebug() << "Unexpected ClipWorkflow::State when rendering:" << cw->getState();
         cw->getStateLock()->unlock();
     }
     return ret;
@@ -165,7 +169,7 @@ void                TrackWorkflow::stopClipWorkflow( ClipWorkflow* cw )
     }
     else
     {
-        qDebug() << "Unexpected ClipWorkflow::State when stopping :" << cw->getState();
+//        qDebug() << "Unexpected ClipWorkflow::State when stopping :" << cw->getState();
         cw->getStateLock()->unlock();
     }
 }
@@ -178,7 +182,7 @@ unsigned char*      TrackWorkflow::getOutput( qint64 currentFrame )
     static  qint64                              lastFrame = 0;
     bool                                        needRepositioning;
 
-    needRepositioning = ( abs( currentFrame - lastFrame ) > 3 ) ? true : false;
+    needRepositioning = ( abs( currentFrame - lastFrame ) > 1 ) ? true : false;
     while ( it != end )
     {
         qint64          start = it.key();
@@ -189,6 +193,7 @@ unsigned char*      TrackWorkflow::getOutput( qint64 currentFrame )
         {
             if ( needRepositioning == true )
             {
+//                qDebug() << "Repositionning to" << currentFrame << '(' << (float)( currentFrame - start ) / (float)(cw->getClip()->getLength()) << ')';
                 ret = renderClip( cw, true,
                                   ( (float)( currentFrame - start ) / (float)(cw->getClip()->getLength()) ) );
             }