[Feature Request] Allow position of subtitle not follow video zoom

Description

Now the position of subtitle follow video zoom, in some case, it is not reasonable.

Expected behavior

Add an option to make the subtitle display of the video with subtitle track not follow the video zoom, so that when the video is zoomed in, the subtitles can still be displayed completely.

Screenshot / video

Right when not zoom in

Wrong when zoom in

Right with mx player when zoom in

option "Fit subtitles into video size" on mx player

App mode

Smartphone