If you have a separate subtitle file (like an .srt ) for this release, you can use several methods to combine them:
Open MKVToolNix and drag your video file and subtitle file into the "Source files" section. Check the boxes for the tracks you want to keep.
Click "Start multiplexing" to create a new MKV file with the subtitles embedded.
: This is the industry standard for MKV files. It "remuxes" the file to include the subtitle track without re-encoding the video, meaning there is no loss in quality .
: Often include English "hardcoded" subtitles for foreign dialogue sections, but rarely include full optional (soft) subtitle tracks unless specified in the release notes.
: For temporary viewing without changing the file, rename your subtitle file to match the video file exactly (e.g., Nix.2022.WEBRip.x264-ION10.srt ) and place it in the same folder. VLC will automatically detect and load it.