(sorry for my english)
I have the same problem .. signal is not emitted ...i know that i need to add a event loop to the app but i don't know where and how ..

My app is a producer/consumer problem that i solve with WaitConditions and a Circular Buffer.. So i have a main Thread and two sub-threads Producer and Consumer
i the code the Producer emit a signal that i need to use to update some information to show.

This is a console app.

Some snippet of the code:

ProducerThread
Qt Code: 
  1. ProcessingThread::ProcessingThread(FrameBuffer *imageBuffer, double inputSourceWidth, double inputSourceHeight,QObject *parent) :QThread(parent){
  2.     this->buffer = imageBuffer;
  3.     this->stopped      = false;
  4. }
  5.  
  6.  
  7. void ProcessingThread::run(){
  8.  
  9.     while(1){
  10.          // Stop thread if stopped=TRUE //
  11.         stoppedMutex.lock();
  12.         if (stopped)
  13.         {
  14.             stopped=false;
  15.             stoppedMutex.unlock();
  16.             break;
  17.         }
  18.         stoppedMutex.unlock();
  19.         // Get frame from queue
  20.         this->currentFrame = buffer->getFrame();
  21.         if(this->currentFrame.empty()==false){
  22.             //Do the heavy work
  23.             emit newFrame();
  24.         }else{
  25.             qDebug()<<"Se recibio un frame NULL";
  26.         }
  27.     }
  28.  
  29.     qDebug()<<"Deteniendo el procesado";
  30. }
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The ConsumerThread
Qt Code: 
  1. ConsumerThread::ConsumerThread(FrameBuffer *buffer, int deviceNumber):QThread(), imageBuffer(buffer){
  2.     // Open camera
  3.     capture = VideoCapture(deviceNumber);
  4.     // Initialize variables
  5.     stopped=false;
  6. } 
  7.  
  8. void ConsumerThread::run()
  9. {
  10.     while(1)
  11.     {
  12.         /////////////////////////////////
  13.         // Stop thread if stopped=TRUE //
  14.         /////////////////////////////////
  15.         stoppedMutex.lock();
  16.         if (stopped)
  17.         {
  18.             stopped=false;
  19.             stoppedMutex.unlock();
  20.             break;
  21.         }
  22.         stoppedMutex.unlock();
  23.         /////////////////////////////////
  24.         /////////////////////////////////
  25.  
  26.         // Capture and add frame to buffer
  27.         //....
  28.         //....
  29.  
  30.     }
  31.     qDebug() << "Stopping capture thread...";
  32. } // run()
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So i have a Controller class to get access to this threads
and i Show class to execute this using the controller
The Show class:
Qt Code: 
  1. Show::Show(QObject *parent) :QObject(parent){
  2.     qDebug()<<"Iniciando..";
  3.     controlador = new Controlador(3,3,0);
  4. }
  5.  
  6. void Show::start(){
  7.     qDebug()<"Start";
  8.     if(controlador->isCameraConnected()){
  9.         connect(controlador->processing,SIGNAL(newFrame()),this,SLOT(updateFrame()),Qt::QueuedConnection);
  10.         controlador->capture->start();
  11.         controlador->processing->start();
  12.         controlador->capture->wait();
  13.         controlador->processing->wait();
  14.         controlador->disconnectCamera();
  15.     }
  16. }
  17.  
  18. void Show::updateFrame(){
  19.     qDebug()<<"Update Frame";
  20. }
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But the signal newFrame or is never emitted or the slot updataFrame don't receive the signal..

any idea???