Thank you for your suggestion.

I tried all options, Media Player, Media Player+, ExoPLayer, FFMPEG, all options have no AC3 sound.
Only external Media Player (VLC in my case) works.
I will use external Player, but it is more difficult to use, thank you.

Big question - what use MX player on your device? Internal AC3 or some way for use AC3 from firmware (from mediacodec)...