Video enabled media application leaks memory

Similar to bugs reports a QTBUG-32481 and QTBUG-67280 I am seeing application death due to the running system (QT5.11.2 X11 on 64bt Ubuntu18.04) running out of memory/swap.

Our application is a custom vending system that shows a menu selection and purchase process as expected, but when periods of idle are detected, the screen transforms to play advertising material, cycling through a defined playlist of videos.

The UI is QML based, and we have a page that is dynamically loaded at the point we 'switch to idle' which has a QML Video item to play the video, with the source for that item been updated as one playback completes, with the source of the next video in the sequence.

There are a few other items to allow for user messages etc - these use a FastBlur / Opacity Mask affect to give a blured affect behind the text of the video that is playing beneath.

As each video starts, I am seeing roughly 7MB of memory loss.

Any ideas? I see the 67280 bug is unresolved (but addressed specifically Android in the platform) and 32481 is completed for Windows platform from some time ago!

This as always is a time critical solution for our customer who needs to get the devices in the marketplace.

Regards

Richard