mkvmerge
Merge and extract multimedia streams.
TLDR
Display information about a Matroska file
$ mkvmerge --identify [path/to/file.mkv]
Extract the audio from track 1 of a specific file
$ mkvextract tracks [path/to/file.mkv] [1]:[path/to/output.webm]
Extract the subtitle from track 3 of a specific file
$ mkvextract tracks [path/to/file.mkv] [3]:[path/to/subs.srt]
Add a subtitle track to a file
$ mkvmerge --output [path/to/output.mkv] [path/to/file.mkv] [path/to/subs.srt]
