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QML runs animations on Raspberry Pi very slow



  • My QML applications can run in raspberry pie 3 b and raspberry pie 4 b, I find that when I run animation effects will cause the CPU takes up more than 100%, thus cause the program's graphical animation operation very caton, this is obviously not truly effective use of the GPU to draw graphics, so I need to how to operate the QML program in raspberry pie 3 b or raspberries pie on 4 b can make effective use of GPU to draw graphics animation can run smoothly.

    This is my Raspberry Pi CPU running, 'IU' is my QML graphics program.
    Note: The program is attached to X11 to run.
    截屏2021-03-26 19.21.45.png


  • Moderators

    Run your app with EGLFS plugin, not X11, and make sure you are running RPi's OpenGL driver (you can enable it in raspi-config).



  • @sierdzio Hi. When you say OpenGL driver, do you mean vc4-fkms-v3d? Cause I have a similar issue as the OP. I have a simple QML app which is running smoothly on FullHD on any raspberry, but if I run 4K on Raspi 4, it gets very choppy... Again the app is very simple, just text animations.


  • Moderators

    Yes I mean the vc4.

    Not sure about 4k, I've never tested it on such a big screen.



  • @sierdzio Seems to me that the problem is mostly apparent for animations that include some transparency interpolation. If the scene just shifts texts back and forth, that doesn't seem to be impacted much. Does that make any sense?


  • Moderators

    Yes, RPi has a weak GPU and OpenGL driver is not optimized very well. What you describe seems consistent with some corner case where optimization is lacking.



  • @sierdzio OK thanks for letting me know. At least I know it's not driver related and can optimize the app not use that kind of animation much.


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