I'm trying to achieve the following:
I have an mp4 file with a single stream, for which I created an
.ass file (it is important that the styling and positions in
.ass are preserved when hardsubbing).
I used avidemux with subtitle filter to hardsub them into the video stream, but the result is a single stream with hardcoded subs.
For some reason my goal is to create a 2 stream mp4 container file, with subtitle stream being separate from the main video stream, so it can be turned off if neccessary.
Can I achieve this using avidemux or some other open source software?