Displays black frame or distortion

I use my smartphone to output video to Gechic monitor. Why there is a black area around the video?

Sorry, the monitor can only received the image signals sent by the smartphone. The black frame is caused by the output format of the smartphone . If the format of smartphone video output couldn’t fill up the 16:9 FHD screen, the black frame area appreared.

When I connect smartphone to Gechic monitor, the screen images do not display in its original size!

Please enter OSD’s “Aspect Ratio.” And then turn off “Overscan” to solve the problem of the screen images being enlarged.