<![CDATA[Video player not work in child dialog. Error:Failed to activate video surface]]>From my video analysis project, In MainWindow, I have one QMediaPlayer and setVideoOutput(subclassVideoSurface) to play video. It is work well. And a button to show one child dialog, this dialog also has QMediaPlayer and setVideoOutput(subclassVideoSurface) to play another video. but, it was not work after MainWindow's palyer had some operate. eg: i paused MainWindow's player before child dialog to show.

I found the demo(Qt5.7.0/Examples/Qt-5.7/multimediawidgets/customvideosurface/customvideowidget) to test my problem.

It had the same question.

If the first player not play video, the child dialog's player can work well.
If the first player played one video and pause it, the child dialog's player can not to work. and had the Error message: Failed to activate video surface

I modified the demo at here, you can download it to test the problem.

Download test demo

]]>https://forum.qt.io/topic/84070/video-player-not-work-in-child-dialog-error-failed-to-activate-video-surfaceRSS for NodeSat, 27 Jun 2026 03:23:57 GMTWed, 11 Oct 2017 02:32:20 GMT60<![CDATA[Reply to Video player not work in child dialog. Error:Failed to activate video surface on Thu, 12 Oct 2017 20:01:50 GMT]]>That's why I'm suggesting to test a more recent version current is 5.9.2.

]]>https://forum.qt.io/post/420458https://forum.qt.io/post/420458Thu, 12 Oct 2017 20:01:50 GMT<![CDATA[Reply to Video player not work in child dialog. Error:Failed to activate video surface on Thu, 12 Oct 2017 00:55:14 GMT]]>@SGaist

I used Mac, I let one friend to test it on Windows10, It had not the problem. So it is maybe the cause of operating system.

]]>https://forum.qt.io/post/420278https://forum.qt.io/post/420278Thu, 12 Oct 2017 00:55:14 GMT<![CDATA[Reply to Video player not work in child dialog. Error:Failed to activate video surface on Wed, 11 Oct 2017 22:03:17 GMT]]>Hi,

What OS/Distribution are you running on ? Can you also check with the latest version of Qt ?

]]>https://forum.qt.io/post/420262https://forum.qt.io/post/420262Wed, 11 Oct 2017 22:03:17 GMT<![CDATA[Reply to Video player not work in child dialog. Error:Failed to activate video surface on Wed, 11 Oct 2017 05:03:19 GMT]]>@jsulm

mainwindow----> obj1 = new player ---> sur1 = new surface ----> obj1.setVideoOutpus(sur1)
child dialog----->  obj2 = new player ---> sur2 = new surface ----> obj2.setVideoOutpus(sur2)

same subclass surface, different object to used.

]]>https://forum.qt.io/post/420044https://forum.qt.io/post/420044Wed, 11 Oct 2017 05:03:19 GMT<![CDATA[Reply to Video player not work in child dialog. Error:Failed to activate video surface on Wed, 11 Oct 2017 04:17:08 GMT]]>@joeQ Do you set same surface in both QMediaPlayers?

]]>https://forum.qt.io/post/420035https://forum.qt.io/post/420035Wed, 11 Oct 2017 04:17:08 GMT