So maybe a big issue with dmabuf & ion_buffer handling is solved in next NE nightly. At least it’s now possible again to restart Kodi more than 1 time 
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Luckylukz confirmed to me in PM that the artifact bug was reproducible by disabling the interface scaler.
You need to be a bit more in detail! Disable GUI scaling enabled or disabled?
If the option is enabled it limit fb to 1080p, if disabled it uses Kodi 4k inbuilt scaling.
Disable GUI scaling = “check” the “Disable GUI scaling” option. When this is the case, artifacts appear, but particularly when the OSD appears when playing 1080p@30hz videos.
Unrelated question : Did the CE devs create this scaling ?
It’s history and was since day one there. It’s somehow the 4k Kodi GUI have issues and with this option enabled the GUI is 1080p and scaled by kernel to 4k.
Maybe @Ray or @TheCoolest knows more about it.
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Thank you for this info. The problem with this scaling method is that it generates a lot of aliasing on some covers. On 65" and larger TVs, it’s very visible. The rendering is much better without it. Finally, that’s not counting the artifacts. The ideal would be to review the scaling method, perhaps drawing inspiration -be newer methods employed (DLSS2). Or just debug mode without Scaling. I did not have these artifacts on my previous boxes. Quite frankly, without this problem, for me this VIM 4 would be the current best box for CE From afar! The other “small” bugs I’ve reported are much more occasional. We can live with them. It’s the best, for its ergonomics (Oowow), for its performance (flop)/consumption/size ratio. You can create high definition environments without affecting the fluidity of the interface. This is unprecedented for a low-power box. Good if anyway. This story of HD sound is still surprising. Surprised it took so long.
I’m putting a video sample that favors the presence of these artifacts and an extract of what it looks like : 652.33 MB folder on MEGA
Last time on NG the audio part took 1-2 years.
And for your scaling issue solve is may best you join Amlogic and help them about how to adjust the hardware registers. We have no such special developer for this and even no complete register description.
So I would see to talk about a scaling that would make the best use of the chipset with Amlogic.
But in the meantime, isn’t it possible to debug the display without scaling ? This problem does not appear on other OS (Linux, Android). So I guess it comes exclusively from CE. I think it’s an image sync issue.
By the way, a remark :
This is uniquely noticeable on the OSD when playing 1080@30hz and 4k@60 and 4k@59.940 video. But it is also present outside reading when the interface is set to 60hz, 30hz and 59.940hz. (present when entering a file and coming out of it, for example). On the other hand, if the interface is at 50hz, or at 24hz, there is no artifact. Ditto in 4k@24, or 4k@50 video playback, no artifacts. So, i assume that the problem is related to the refresh (30hz, 59hz and 60hz).
The question is who will invest hours/days for debugging, research and trial and error for Hobby?
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I think that the last time we looked into this was like 2 or 3 years ago.
Eventually, I think that we reached the conclusion that this was a hardware limitation. Possibly memory bandwidth limit, or something like that.
Normally, at 4K resolution, the GUI is downscaled to 1080P. With the scaling disabled, the GUI is rendered at 4K, which doesn’t work well on some devices. On some it’s “usable”, where the artifacts are rare. On others it’s unusable at all because it messes up everything on screen.
Edit :
Thank you for these clarifications TheCoolest.
A hardware limit ? But then why do we not encounter these artifacts on other OSes in 4k@60hz ? Even Kodi on Android does not have this problem. And I don’t believe in a memory limit, because these artifacts are not present in 4k@50hz, 30hz, 24hz (Artifacts disappear with a frequency other than 60hz.).
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I don’t have a technical explanation. It’s what I remember we were able figure out when we spent time on looking into it. It’s also possible that the techniques used by the different OSes to render the GUI are different, which may result in the difference in behavior you see.
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100% Agree !!
Hi all, by the way.
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Has the custom disp_cap feature been removed now? I don’t see any mention of it in the log, and with CE-19 I used to sometimes have issues with EDID data because powering on devices at different times.
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Are there any plans to phase out Matrix nightlies and start with O nightlies? 
There aren’t any new CE-19 nightly builds already since some time. CE-21 Omega is ready from our side but there are some missing components from LE to be able to make a useful build.
I have discovered an oddity in NG 20 nightly (CoreELEC-Amlogic-ng.arm-20.1-Nexus_nightly_20230302) which is still present in the latest build.
SD Content that is around 360p has stuttering that looks as if frames are being missed during playback. Audio is fine though.
480p and above seems perfectly fine.
Playback in the the build immediately prior to CoreELEC-Amlogic-ng.arm-20.1-Nexus_nightly_20230302 is fine.
Small sample attached.
Marjorie Taylor Greene Says Something We NEVER Thought She’d Say.mkv (3.0 MB)
The video is taken directly from YouTube, where, if you were to use the Play to Kodi addon, the same stuttering also occurs when streaming using this addon.
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There is rework of the hw/frame buffer ongoing. But it might be finished with tomorrow nightly 20230304, maybe. Please test than again.
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20230304 fixes the problem, along with another that I forgot to mention, where setting 4:3 videos to be played 16:9 resulted in a distorted image, requiring a manual change from normal to 16:9 when playing a video.
Thanks.
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