[mike76]

Have you enabled them in the whitelist?

 Yes.
I try to play a 1920x1080 24Hz .mkv video.
I add this resolution in whitelist, but Kodi play the file at 1920x1080 50Hz (i set this resolution by default on my shield).

Probably the file is at 23,997 Hz (and not 24Hz), i must match 1920x1080 23,997 in Kodi whitelist? I thinks i don't see this resolution in the list.

No problem with SPMC. The same file start regulary at 1920x1080 24Hz.

How are you checking the file is playing at 50hz?