Hi everybody, I have a quite serious problem and maybe someone here can help.
Qt 6.4 (and 6.5 beta as well) on Windows seems to have some serious issues regarding VSync if video playback and animations are combined (simple example: video playing and a rotating rectangle on top). If the animation is running, it seems that the video frames are presented in wrong order. The video jumps and stutters. It does not if I disable vsync by setting the sync interval to 0 and can be improved using Nvidia settings (Fast / Low Latency etc., happens on Intel HW as well, though) but is always notable. While the video runs perfectly when Vsync is off, nearly all animations (especially those changing x / y positions) look horrible then, so this is not a solution. A similar effect can be observed when multiple videos are playing in parallel, in particular if they have different frame rates. I digged a bit deeper into QQuickVideoOutput and QSGVideoMaterial and I'm confident that all frames arrive at the correct time in the correct order for presentation but "something" later messes things up. If I force the use of hardware video textures off which "solved" the issue, but of course is pretty much unusable from a performance perspective. This happens using OpenGL and Direct3D. There are some bug reports that contain some extra info (videos to demonstrate the effect, logfiles, etc): https://bugreports.qt.io/browse/QTBUG-111459 https://bugreports.qt.io/browse/QTBUG-109213 Every fix, workaround or just general idea where to have a look is highly appreciated (deadline for important project is coming nearer). Thanks and kind regards Dominik
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