Merge subtitles with mkv
Some streaming servers/devices don't support external subtitles (Ex: DLNA(/minidlna)).
Merging subtitles with mkv files solves this problem, also for downloading to other devices without the need of subtitles don't get downloaded.
merging with mkvmerge:
mkvmerge -o movie.mkv movie.mp4 --language 0:eng english.srt --language 0:fre french.srt
https://mkvtoolnix.download/doc/mkvmerge.html#mkvmerge.examples