[noggin]

Huh, for some reason I thought all of the DVD MPEG-2 stuff was software decoded these days for Kodi (and forks).

Been thinking about this further. I wonder if the AMLogic platforms have reverted to software decode and deinterlace for DVD and the code/SoC just isn't up to a decent deinterlace at the moment then? The Pi uses hardware decode for DVDs I believe - but you could be right about other ARM platforms.

*EDIT : Of course, you're right. The Wetek Core uses am-mpeg2 (hardware decode?) for decoding MPEG2 SD for Live TV, but ff-mpeg2video (software decoding? or hardware decoding via ffmpeg?) for DVD Video playback. I remember that this was the case back in the day (was it to handle DVD subtitles?), but I'd assumed other platforms worked a bit more like the Pi with hardware MPEG2 decode and deinterlace to mitigate the relative low-power of the platform. OR does ff-mpeg2video still use hardware acceleration, but via a different route ?

The am-mpeg2 hardware decode for interlaced content will (I assume) be deinterlaced via the hardware deinterlacer, but I'm not sure what happens with the ff-mpeg2video decoded content. It doesn't appear to max out any CPU cores - so the dropped frames don't appear to be caused by hitting the CPU limits during deinterlacing. So either the software decode and deinterlace is flawed, or there is some attempt to pipe back software decoded content through the hardware deinterlacer that isn't working? (25p content with no motion between the two fields in the frame plays back OK if you disable deinterlacing, so the core decode appears to be OK, though possibly something timestamp-y is causing issues with the deinterlacer?)

** EDIT 2 : Just compared to my Pi 3. With a licence key for MPEG2 you get mmal-mpeg2 decode for Live TV, without you get ff-mpeg2video (I assume software only) for Live TV. With a licence key you get mmal-mpeg2 decode for DVD content too, without the licence you get ff-mpeg2video (but without the jerkiness of the AMLogic stuff)

So the Pi uses the same codec for both DVD and Live TV (hardware acceleration - and you can chose between mmal and omx routes in the hardware acceleration menu) - but the Core doesn't. Is this because am-mpeg2 doesn't work with VOB content or because the Pi, unusually, has switched away from ff-mpeg2video for DVD playback?

** EDIT 3 - earlier checks were with native progressive content (which still has issues if you don't disable deinterlacing on the Core, but doesn't on the Pi3). However native interlaced content doesn't deinterlace properly on the Pi 3 either with MMAL decode, but does with OMX decode... (Still with MMAL Advanced deinterlace.)