Video "stuttering" on KODI / auto switch frame rate [S905X2]

Compuman

I would like to write my experience with video player on new S905X2.
On the start:
-with old S905X and S912 I normally install Libreelec (on SDCARD) to use KODI with correct auto frame rate switch and audio pass-through to my audio system
-this S905X2 is not supported (for now) in Libreelec, so I have to use Android also for KODI


I tried different version the result is that:
KODI 18.1 video stuttering with auto frame rate by a script (freaktab)
KODI 17.x video stuttering with auto frame rate by KODI add-on

Then I use Amlogic TV Box tool to enable FTMC and SPMC frame rate switch

SPMC 17.6a2 (alpha) without amlogic codec,  have strong audio stuttering ... not usable at all
SPMC 16.7.04 works well, but some problem with audio stuttering or audio sync with some video file
FTMC 16.2.31 works worst that SPMC, some file have video stuttering

I can't believe that everyone view movie or tv show, with this problem...
but NOW I can't use this BOX for video player

can someone give me a help?