ffmpeg -itsoffset -2.5 -i midv912engsub.srt -c copy shifted.srt (Shifts subs 2.5 seconds earlier – adjust sign as needed.)
ffmpeg -i midv912engsub.mkv -vf "subtitles=midv912engsub.srt" -c:a copy output_hardsub.mp4 If subtitles are internal: midv912engsub convert015856 min
ffmpeg -i midv912engsub.mkv -c copy -c:s mov_text output_softsub.mp4 For MKV to MKV with subtitles intact: ffmpeg -itsoffset -2