Just had another look at it. At the end of the day the Pi 4 still does not have enough power to software decode smoothly. When it plays a low bitrate scene is runs smoothly and the CPU usage is a 30-40% in that example. In high bitrate scenes the CPU usage is at max and I get that too-slow-then-too-fast-playback again.
I'ss try out if enabling syncing refresh rate to display helps
Update: Just updated to Libreelc 10 with Kodi Matrix and now the frame drops are gone, but the VC1 Blu Ray rips still don't play smoothly. The movie runs too slow for half a second and then too fast for another half a second. It's just slightly, but still easily noticable
That does not seem to be it. "sync playback to display" was already off and the video file wasn't interlaced to begin with.
I also already overclocked the pi to 1750MHz and it seems to help a bit with the issue
I noticed that playing VC-1 endoced files leads to alot of dropped frames. In the first two minutes of the Blu Ray rip of The Boure Identity it says 86 dropped frames in the ctrl+shift+o overlay.
The problem seems to be that the PI 4 does not have hardware acceleration for VC-1, unlike the Pi 3, and that the CPU is not quite powerfull enough to decode it via software. What make me belive that is
I tried all kinds of different setting like "automatically changing the screen refresh rate" on and off and "audio pass through" on and off, but nothing affects the dropped frames. I'll try overclocking the Pi in the next couple of days and see if that helps. Are there any other thinks I can try to imporve the situation?
