I’ve installed CoreELEC 9.2.5 image to eMMC and see sometimes random distributed colored pixels during 4K HEVC playback. The phenomenon appears like I experienced using overclocked graphic cards in the old times. This mostly happened with over-driven VGA RAMs. The SOC temperature is 52 Celsius so the heat mustn’t be a problem. Is it possible that the LPDDR4x RAM on board is defect? How may I test it? Does anybody see similar defects?
At the moment, I advise you not to consider any kind of test programs, first you need to try all the standard coreelec recording options, then, we will be able to draw conclusions and proceed to further steps.
Something similar can be found on Android.
If you are afraid of losing data, I advise you to make a backup, coreelec provides this function.
Tested with CoreELEC nightly 01162021. I had only a very short time to test. For now it seem to me that the official nightly has not the problem I saw on the Stable one from Khadas repo.
Will test further.
I had half an hour again to testing. The new nightly (01202021) seems to play 4K HEVC without glitch too. Set up type 1 buffering in advancedsettings.xml for further testing but everything played nice again. Under System/CoreELEC switched on ’disable NR’ and that had no problematic effect on the playback.
Booted to stable KHADAS CoreELEC 9.2.5 on the eMMC again and under System/CoreELEC switched off ’enable HEVC seek workaround’. For surprise the random distributed colored pixel errors were missing completely. My test was not extensive, only a short one but maybe fund the culprit.
Found the definite culprit.
Random distributed colored pixels when playing high bit-rate 4K HEVC content on a311d with CoreELEC 9.2.5 is not a hardware problem. Switch off under System/CoreELEC ’enable HEVC seek workaround’ and the problem will be gone. Thank you for all of your assistance.
There is a bug with a hardware decoder enable on corelec since the beginning. If you disable it, you can see the hevc videos correctly.
go to kodi settings, player/settings/ render method and disable amcodec.