EDIT [2020/04/29 - apparently solved ?]
EDIT [2020/04/29 - see here: LibreELEC 9.2.X video judder and stuttering [renamed]]
As suggested, I'm reposting my message originally in announcement tread:
I’m running LibreELEC-RPi4.arm-9.1.501 in my Rpi 4.
I’ve noticed that some video does not play smoothly.
There is judder, jerkyness and stuttering (lost frames?).
The odd thing is that no report whatsoever in kodi.log.
Butthe result is very unpleasant to watch.
It happens with 23.976fps material and also live-tv @25fps.
In the first case, kodi switches the tv to 23.976fps in the second one to 50fps (as it should be).
Kodi.log reports the correct fps switching.
But Looking to the video playback there’s a lot of strange motion artifacts, as if kodi is processing output to another fps different from the one it is outputting.
I have configured “Adjust Display Refresh Rate” as “start/stop”.
a) In version LibreELEC-RPi4.arm-9.1.501 this seems to happen only if I have audio with “Allow Pass Trough” enabled. Disabling it, the video runs fine!
b) In version LibreELEC-RPi4.arm-9.1.002, I found a turn around by forcing “Adjust Display Refresh Rate” as “always”.
My TV is a SONY Android TV from 2016.
Note: I also have a RPi 3, with same configurations, in which all goes very smoothly.
Hope this can be fixed in the next releases.
Keep up the great work supporting the Pi 4