Is it possible to record a dynamic QWidget into a video?



  • Hi,

    I am recently using QOpenGLWidget to draw something in the runtime. I wonder if it is possible to record the whole drawing process into a video. I found a bunch of examples saying Qt5 could support multimedia by using webCam(QCamera). However, it didn't say if this camera can be set the target to QWidget itself. Any idea? Thanks!

    Note: Qt5.6.2 (Could upgrading if needed), Ubuntu16.04



  • The only way I could think of is using QScreen::grabWindow() and QTimer to save my widget's screen shots sequentially. And how could I make this raw image data to a video?


  • Lifetime Qt Champion

    Hi,

    Do you want that integrated in your application or would like to just record what is happening for some other purpose ?



  • for sure it is integrated in my application. Right now I have a solution that using openCV's VideoWriter to grabFrameBuffer() per frame and write it into a VideoWriter. However, this grabFrameBuffer() function seems a pretty heavy task that causing my output video sometimes flickering. I don't quite care about what is rendering currently in my window, I am caring the output video that should seem to be fluent enough.

    My render method is based on QOpenGLWidget. Right now I want to use a FramBufferObject to "steal" content from my paintGL() function call every frame. And using QOpenGLGFrambufferObject::toImage to get an image and write it into a video. However right now I could only "steal" black screen in my window. and my window is rendering nothing for sure. I think there might be a way to hand over all gl's draw calls and save it into my framebufferobject.


  • Lifetime Qt Champion

    You should post the code you are currently using. That will allow other eyes to take a look at it and maybe find what is happening with it.


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