Default [Q] Mx tv box android to Linux

I have one issue with my mx tv box (running Linux) with my home cinema my tv is LG 55LA860W and I connected with optical to my home cinema
And when I try to watch a film from my tv box with dts sound it shows me from the beginning the logo recognize the dts the sound starts perfectly to my speakers but only for 15-20 second's after that the sound stops and start one annoying sound,
pls somebody if he can help I will thankful
P.s: Sorry for my English