Solution:
This is a compatibility problem. After the box and TV host is connected to the third-party TV via the HDMI cable, the resolution option is provided by identifying the EDID information of the terminal. The purpose is also to shield the resolution that is not supported or uncompatible.
1. Confirm whether the MI box and TV terminal supports 4K resolution.
① Some models of Mi box support output of the maximum resolution of 1080P;
② If the resolution of the TV terminal is 1080P, then the box setting interface cannot be selected to 4K resolution (in order to avoid the problem of black screen caused by too high output resolution).
2. Try to connect to other HDMI ports of the terminal.
Third-party TV may come with HDMI ports of different standards.
3. If you want to output 4K@60Hz, the TV interface needs to support HDMI2.0 standard.
4. If the TV supports HDMI2.0, but the box still cannot choose 4K@60Hz, the HDMI2.0 function needs to be turned on at the TV end.
① If using the Mi TV host or Mi home theater, then may also need to open the terminal HDMI2.0 option.
② The position of third-party TV to open HDMI2.0 option may not be fixed, generally after the TV enters the signal source interface, press the menu button of the remote control to see.
