Hi, i recently downloaded a DVD file (with its respective *.BUP, *.IFO and *.VOB files in it), i would like to add a subtitle to the movie.

I found a guide related to this problem (https://www.videohelp.com/forum/viewtopic.php?t=219535)

as I read it, it says somewhere u need to demultiplex audio and video and other complicated stuff.
My question is: Is it necessary to demultiplex audio and video and all that stuff? All i need is to add a subtitle.
Thanks everyone