Hi all, I spent a lot of time to pinpoint this problem and I wonder if it's a bug of QtGstreamer or not. If it's not, we seriously need to make this thing more clear on the documentation and prevent others from making the same mistake as I did. I wrote a VideoPlayer class to deal with video files using QtGstreamer under the hood. I was able to instantiate a VideoPlayer object and display the video with no problems. Then, I tried to destroy the current player and instantiate a new one (within the same thread) to watch another video. That's when it happend: the second object failed to create it's pipeline. Hours of investigation went by until I found the source of the problem: the constructor of VideoPlayer initialized the library through "QGst::init();" and the destructor did the opposite with "QGst::cleanup();". It was my understanding that after a <a href="http://gstreamer.freedesktop.org/data/doc/gstreamer/head/qt-gstreamer/html/namespaceQGst.html#af854931adda54e40b759bf4f736f1cbb">cleanup()</a> operation, a call to init() would restore things back to it's operational state, but so it happens that cleanup() makes it impossible. What is also strange is that calling QGst::init() after a cleanup() doesn't return any errors nor throw exceptions, which I think it should, since you can't use the library to create a new pipeline rendering it pretty much useless. I wrote a small demo to reproduce this behavior: #include <QObject> #include <QGst/Init> #include <QGst/Pipeline> #include <QGst/Element> int main() { qDebug() << "#1 call QGst::init()"; QGst::init(); QGst::PipelinePtr _pipeline = QGst::Pipeline::create(); if (!_pipeline) { qDebug() << "#1 Failed creating pipeline !!!"; return -1; } qDebug() << "#1 Setting pipeline to Playing"; _pipeline->setState(QGst::StatePlaying); qDebug() << "#1 Setting pipeline to Null"; _pipeline->setState(QGst::StateNull); qDebug() << "#1 call pipeline.clear()"; _pipeline.clear(); qDebug() << "#1 call QGst::cleanup()"; QGst::cleanup(); qDebug() << "\n* Press <enter> to restart the pipeline setup"; getchar(); qDebug() << "#2 call QGst::init()"; QGst::init(); _pipeline = QGst::Pipeline::create(); if (!_pipeline) { qDebug() << "#2 Failed creating pipeline !!!"; return -1; } return 0; } Thanks! -- Karl Phillip