QtWebEngine and Adobe Connect (Flash Player): can't switch between cameras in qt based application

[boergi]

I need to use Adobe Connect in Ubuntu 18.04. As there is no application for linux systems, i basically want to call a Adobe Connect URL with QtWebEngine (so i can add e.g. camera settings via widgets later). For this, i chose the simple browser example from Qt. I can login and enter the room, which causes the Adobe Flash Player to start as expected. In the beginning, i had to add a slot for receiving the QWebEnginePage::featurePermissionRequested signal to grant permissions, because the flash player needs access to multiple cameras.

This seems to work fine, at least i can see the camera stream now. But whenever i want to switch to another camera (via the drop-down menu inside the flash player application), the camera-window gets black for a short period and then the same camera is shown again, independent of the choice in the drop-down menu. I also tried using the QWebEnginePage->settings() commands, which allows me to enable plugins, javascript, etc but it had no effect.

Another thing i noticed: when the flash player app gets opened for the first time, no camera names are listed. If i start a camera i get asked and i allow the permissions. Now i close the tab and open it again. The camera names are listed now, but it still only shows the first one, no matter what camera is selected.

I tried it on Chromium and everything is fine (because as far i know QtWebEngine is chromium-based). Chrome and Firefox work also.

Anyone got an idea how to fix this problem?