SPMC AMCodec Acceleration on Android 7.1.2

[AMKnock]

Hopefully someone is still active on these boards and can maybe help me out.

As we all know, using AMCodec acceleration on Android Marshmallow causes SPMC to crash.
However, if you add the line libamcodec.so to public.libraries.txt in system/etc folder, it should work.

Well, now it doesn't crash anymore, but all I get is no video. but audio and subtitles are displayed.
Here is the debug log: https://paste.kodi.tv/neginuzime.kodi

I presume it has something to do with these two errors:
ERROR: SetInt: error opening /sys/class/video/contrast
ERROR: SetInt: error opening /sys/class/video/brightness