I haven't try the tweak myself but it had been confirmed with several users at the Kodi forum. Sad, it reset with every reboot. unless a permanent solution is found, i not going to try it yet.
https://forum.kodi.tv/showthread.php?tid=275083&page=126 https://github.com/koying/SPMC/issues/1036#issuecomment-341298748
Just want to update: it seem someone already reported this. https://www.reddit.com/r/AndroidTV/comments/7ab4hw/mibox_enable_amcodec_in_spmc/
why would you wnt to reboot :), mine works 24/7 without any issues now with auto resolution refresh switching