>>737001I think Avidemux only supports hardcoding them (video > filters > subtitles), which is probably not what you want.
But independent of what tool you use, mp4 is a really bad container for subtitles and only accepts its own custom format. So if you have complex .ass subtitles (with styles, positions and colors) converting will completely butcher them. Text-only like .srt can be converted no problem though.
Like the poster above recommended, FFmpeg can do it all (though not with the command they posted; that would be hardcoding subs as well), but it's obviously not very approachable. I don't know a lightweight tool with a GUI that handles mp4 subtitles well. Most even fuck up with basic trimming (since subtitle files contain absolute timings which would have to be adjusted/rewritten in line with how you trim the video).
