Does your StreamThread inherits from QThread? If not you have the answer. I think generally you have a problem here because you are using singal/slot mechanism which was designed for GUI not for normal (fast) operation. I could not find it in the documentation (somebody please correct me if wrong) but my guess is that signal/slot mechanism is using qtimer. Excerpt from the documentation: "In general, emitting a signal that is connected to some slots, is approximately ten times slower than calling the receivers directly, with non-virtual function calls." From here <a href="http://doc.qt.nokia.com/latest/signalsandslots.html">http://doc.qt.nokia.com/latest/signalsandslots.html</a>. So if you want some real-time processing to happen and you have a producer-consumer scenario I would suggest to use semaphores (QSemaphore ) for that. Otherways (if qtimer is involved in multithreading) you will get performance issues sooner or later. Checked on my own skin. If not I guess it should <div class="gmail_quote">2011/4/13 Matias Hernandez Arellano <<a href="mailto:msdark@archlinux.cl">msdark@archlinux.cl</a>> <blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">(me again)... Well i try it a lot of things and finally i get a proof of concept of the final application semi functional using Qt+OpenCV+QGstreamer ... but.. yet.. i have a problem.. Here some snippets of code main.cpp int main(int argc, char *argv[]){ QCoreApplication a(argc, argv); QGst::init(&argc,&argv); FrameBuffer *buffer = new FrameBuffer(3); FrameBuffer *buffer2 = new FrameBuffer(3); CaptureThread *capture = new CaptureThread(buffer,0); ProcessingThread *processing = new ProcessingThread(buffer,buffer2,capture->getSourceWidth(),capture->getSourceHeight()); StreamThread *stream = new StreamThread(buffer2); QCoreApplication::connect(processing,SIGNAL(newframe()),stream,SLOT(update()),Qt::QueuedConnection); capture->start(); processing->start(); stream->start(); return a.exec();; } buffer and buffer2 are Circular Buffers that hold cv::Mat (OpenCV Images). buffer hold cv::Mat obtained with CaptureThread. ProcessingThread pull images from here. ProcessingThread push images into buffer2 and StreamThread pull images from here. The cycle works good... now the StreamThread StreamThread::StreamThread(FrameBuffer *b, QObject *parent): ImageBuffer(b),QThread(parent){ QString pipe_str = QString("appsrc name=\"appsrc\" caps=\"video/x-raw-rgb,width=320,height=240\" ! queue ! videoparse format=14 width=%1 height=%1 ! videorate " " ! videoscale ! video/x-raw-rgb,width=320,height=240 " " ! queue ! ffmpegcolorspace ! jpegenc ! queue " " ! tcpserversink port=5000 ").arg(WIDTH,HEIGHT); this->pipeline = QGst::Parse::launch(pipe_str).dynamicCast<QGst::Pipeline>(); QGlib::connect(this->pipeline->bus(),"message",this,&StreamThread::onBusMessage); this->pipeline->bus()->addSignalWatch(); this->pipeline->setState(QGst::StatePlaying); this->m_src.setElement(this->pipeline->getElementByName("appsrc")); } void StreamThread::onBusMessage(const QGst::MessagePtr &message){ switch (message->type()) { case QGst::MessageEos: quit(); break; case QGst::MessageError: qCritical() << message.staticCast<QGst::ErrorMessage>()->error(); break; default: break; } } void StreamThread::run(){ this->exec(); } //This SLOT fires up when ProcessingThread calls the newImage() SIGNAL .. // this signal ocurrs when a new processing image was push into the buffer void StreamThread::update(){ if(!this->m_src.element().isNull()){ this->pipeline->setState(QGst::StatePlaying); QGst::BufferPtr buffer = QGst::Buffer::create(WIDTH*HEIGHT*3*sizeof(quint8*)); quint8 *data = buffer->data(); Mat frame = this->ImageBuffer->getFrame(); data = (quint8*)frame.data; QGst::FlowReturn ret = this->m_src.pushBuffer(buffer); if(ret!=QGst::FlowOk){ qDebug()<<"Error pushing data"; } } } StreamThread::~StreamThread(){ this->pipeline->setState(QGst::StateNull); } When i run this app i don't get errors, just this warning (this doesn't show if i don't execute StreamThread) <div class="im">QObject::startTimer: QTimer can only be used with threads started with QThread </div>So i suppose that QGstreamer use QTimer in some hidden part. And... if i try to see the stream using gst-launch tcpclientsrc host=127.0.0.1 port=5000 ! jpegdec ! queue ! video/x-raw-rgb,width=320,height=240 ! ffmpegcolorspace ! queue ! glimagesink sync=false I get: Estableciendo el conducto a PAUSA ? El conducto est? PREPAR?NDOSE ? But the pipeline never goes to PLAYING and nothing happen (i can't see the result)... Any idea?? Thanks in advance <div class="im"> El 08-04-2011, a las 4:34, Tim-Philipp Müller escribió: </div><div><div></div><div class="h5">> On Thu, 2011-04-07 at 18:20 -0400, Matias Hernandez Arellano wrote: > >> It's possible to use gstreamer in a multithread app? > > Yes. > >> I have an Producer/Consumer application where i have two groups 1 with >> 1 Producer and 1 Cosumer (Capture Video with Opencv/Process Image) and >> other group equal ... Take de Process Frame / Stream the frames... > > Have you considered writing a simple source element that captures and > processes the frame directly in a GStreamer pipeline? > >> The communication between threads works good, but know i need to add >> the stream part .. I have another app where i test the functionality of >> AppSrc and works!!! .. So i need to add this (Read from the Buffer >> where i have images, push into AppSrc and Stream over network) in a >> thread. >> >> is this possible?? > > Why would this not be possible? Have you tried it and run into problems? > > GStreamer does (almost) all of its processing in dedicated threads of > its own ("streaming threads"). You should be able to push buffers into > appsrc from any application thread (they will get queued internally in > appsrc and then processed in the GStreamer streaming thread). > > Cheers > -Tim > > > _______________________________________________ > gstreamer-devel mailing list > <a href="mailto:gstreamer-devel@lists.freedesktop.org">gstreamer-devel@lists.freedesktop.org</a> > <a href="http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel" target="_blank">http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel</a> </div></div><div class="im">Matías Hernandez Arellano Ingeniero de Software/Proyectos en VisionLabs S.A CDA Archlinux-CL <a href="http://www.msdark.archlinux.cl" target="_blank">www.msdark.archlinux.cl</a> _______________________________________________ </div><div><div></div><div class="h5">gstreamer-devel mailing list <a href="mailto:gstreamer-devel@lists.freedesktop.org">gstreamer-devel@lists.freedesktop.org</a> <a href="http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel" target="_blank">http://lists.freedesktop.org/mailman/listinfo/gstreamer-devel</a> </div></div></blockquote></div> -- Your Sincerely Michal Joachimiak