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line 1 \ \ \ backslash ampersand entity (also tried N letter entity) neither work in vlc nor in ffmpeg.
line 2 \\n escapes n instead backslash. On vlc it makes backslash and breaks line. On ffmpeg it is backslash and space.
line 3 \⁠n used wordjoiner (U+2060), works
line 4 \​n zero width space, works in vlc, works in ffmpeg.
line 5 \n breaks line in vlc, make space in ffmpeg. <b>Bold</b> tag works in both.
line 6 \<i></i>n works for vlc, but in ffmpeg it is wrong.