[OpenELEC] Video playback problem in Pictures -> “Recursive slideshow” + 1080p

Hi,

I have an Arctic MC001-XBMC machine, been serving me nicely since the happy days of XBMC 12 / OpenELEC 3.0 (it came pre-loaded with these) some 4 years ago.
Since then I periodically upgraded the OpenELEC version, with essentially no issues.
The Arctic comes with:
– Dual Core Intel Atom D525
– 2GB DDR3 1333MHz
– Intel NM10 chipset
– Graphics: ATI Mobility Radeon HD 5430, 512MB GDDR3

A few weeks ago I upgraded to OpenELEC version 8.0.3, which took me from Kodi 15.x to 17.1.
The whole thing works fine, apart from some sluggishness when browsing the UI: everything seems a bit slower than was with Kodi 15, but still manageable. Other than that all else is as before or better, EXCEPT for:
1) The known stuttering issue with certain heavy 1080p video files – it happens also to me but I understand that this is being investigated already in the community
2) The problem described below.

So the problem is as follows:

I use to screen pictures taken by my phone (a Galaxy S7 Edge) using this Kodi machine in my living room. I usually copy the relevant pictures onto a portable HD, connect it to the machine, and in the Pictures area I browse to the relevant folder and use the “Recursive slideshow” menu item to start the slideshow.
One of the nicer features that this slideshow mode allowed so far is the ability to play all pictures in the order taken (filename) and then in case that a video file exists in between the pictures it would play this video as well (this feature was added in one of the Kodi versions a couple of years ago, up until then the videos would be ignored).

The problem with Kodi 17 is that whenever I do the same now, the video would not display – I see just a black screen while the clip’s audio is being played normally.
On the other hand, when I browse to the same folder from the Videos menu and play any such video in that folder, it plays normally with no black screen or stuttering.

Searching for this problem on the web I couldn’t locate anything similar. People having problems with video playback in Kodi 17 were suggested to change the HW acceleration settings. So I went to these settings under Player->Videos (expert mode) and tried to play with these settings, but to no avail – the problem persists no matter what I tried.

FWIW, these are the HW acceleration settings available for me:
– Allow hardware acceleration – VDPAU (disabled by default)
– Multiple sub-options below this for VDPAU mixer, MPEG-2, MPEG-4, VC-1 (all grayed-out as the above is disabled)
– Allow hardware acceleration – VAAPI (disabled by default)
– Multiple sub-options below this for MPEG-2, MPEG-4, VC-1, VAAPI render method (all grayed-out as the above is disabled)

So, I allowed both VDPAU and VAAPI acceleration (although seemingly irrelevant to my ATI/AMD graphics processor?) each at its time and within that I also tried with MPEG-4 on and off. Nothing changed the behavior really, still the black screen remains – or with VDPAU HW acceleration ON, the first frame shows in slideshow mode but freezes at that point.
Bottom line I can’t find a combination of these settings which will allow to play the videos in Pictures/slideshow mode, but only from the Video menu.

The videos I try to play are standard SGS7 files: MPEG-4 format (.mp4), AVC [email protected], 1080p, 29.796fps.

Any help will be most welcome!

TIA