QtGStreamer: How to get run a QGst::Ui::GraphicsVideoWidget ?

[Mandeep Sandhu]

On Thu, Mar 21, 2013 at 2:47 AM, pfarmer <flacone at gmx.de> wrote:

> I am trying to run a simple test video with QtGtreamer. The examples
> provided
> with the QtGStreamer API documentation run successfully. The Voip example (
>
> http://gstreamer.freedesktop.org/data/doc/gstreamer/head/qt-gstreamer/html/examples_2voip_2main_8cpp-example.html
> <
> http://gstreamer.freedesktop.org/data/doc/gstreamer/head/qt-gstreamer/html/examples_2voip_2main_8cpp-example.html
> >
> ) also includes a videotestsrc which is properly displayed.
> Nevertheless a QGst::Ui::VideoWidget in conjunction with watchPipeline() is
> used there. I rather wanted to get it work with the help of a
> QGst::Ui::GraphicsVideoWidget. Therefore I tried following code:
>
> #include <QGst/Init>
> #include <QGst/Pipeline>
> #include <QGst/Element>
> #include <QGst/ElementFactory>
> #include <QGst/Ui/GraphicsVideoSurface>
> #include <QGst/Ui/GraphicsVideoWidget>
>
> #include <QApplication>
> #include <QGLWidget>
> #include <QGraphicsView>
> #include <QDebug>
>
> int main(int argc, char *argv[])
> {
>         QApplication app(argc, argv);
>         QGst::init(&argc, &argv);
>
>         QGraphicsView* view = new QGraphicsView;
>         view->setViewport(new QGLWidget);
>         QGst::Ui::GraphicsVideoSurface* surface = new
> QGst::Ui::GraphicsVideoSurface(view);
>         QGst::Ui::GraphicsVideoWidget* widget = new
> QGst::Ui::GraphicsVideoWidget();
>         widget->setSurface(surface);
>
>         QGst::ElementPtr source =
> QGst::ElementFactory::make("videotestsrc");
>         QGst::ElementPtr sink = surface->videoSink();
>         QGst::PipelinePtr pipeline = QGst::Pipeline::create();
>         pipeline->add(source);
>         pipeline->add(sink);
>         if(source->link(sink) == false)
>                 qDebug("Link failed");
>
>         view->show();
>         pipeline->setState(QGst::StatePlaying);
>
>         return app.exec();
> }
>
>
> This code is running, but the widget stays empty. What is the mistake I
> made?
> Hopefully this is the right place to ask questions about QtGStreamer.
>

I don't think there's any 'gstreamer' issue in your code. I haven't done
much of Qt graphicsview programming, but a cusrory glance on the docs
showed that you seemed to have missed creating a scene.

Something like:

QGraphicsScene* scene =  new QGraphicsScene;
QGraphicsView* view = new QGraphicsView(scene);

Later you will have to add your GL widget to the scene:

scene->addItem(widget);

The gstreamer part of your code looks ok.

HTH,
-mandeep



>
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