MKVToolNix useful commands

mkvtoolnix.sh

# https://www.fosshub.com/MKVToolNix.html
$ sudo apt install mkvtoolnix

# Update the default audio track to the second one in all the files in the current directory
$ for i in *; do if [[ $i == *.mkv ]]; then mkvpropedit "$i" --edit track:a1 --set flag-default=0 --edit track:a2 --set flag-default=1; fi; done

# If you have a single subtitle, and you want it to be default, then do:
$ for i in *; do if [[ $i == *.mkv ]]; then mkvpropedit "$i" --edit track:s1 --set flag-default=1; fi; done

# Merge two files into one
$ mkvmerge -o output.mkv firstfile.mkv + secondfile.mkv

# Identify your tracks for a given file
$ mkvmerge --identify [filename]

# Hardcode subtitle file into video file
$ ffmpeg -i mymovie.mp4 -vf subtitles=subtitles.srt mysubtitledmovie.mp4

# Merge subtitle file to video
$ mkvmerge my_file.mkv -o "new_file.mkv" --language 0:en my_subtitle.srt

# Convert ANSI .srt file to UTF-8
$ iconv -f "windows-1252" -t "UTF-8" import.csv -o new_import.csv

# Extract srt from mkv file
# The first number is which input you select (0 is the first and only input in my command),
# second character is what type of stream you select (s is subtitles, a is audio, v is video),
# third is which stream you select out of those (if you have two subtitles, you can put 0 or 1).
# So like this: -map input_file_index:stream_type_specifier:stream_index
# So the code above takes the Movie.mkv, then its subtitle streams, then the first subtitle stream. (counting starts with 0, because it's an index.) 
$ ffmpeg -i Movie.mkv -map 0:s:0 subs.srt

# Some useful for loops
$ for i in {1..10}; do iconv -f "windows-1252" -t "UTF-8" "$i.fr.srt" -o "$i.new.srt" && mkvmerge "$i.mkv" -o "$i.new.mkv" --language 0:fr "$i.new.srt" && echo "Processed file $i successfully" || echo "Failed to process file $i"; done

# Get all information from an mp3 file
$ sudo apt update && sudo apt install ffmpeg
$ ffprobe -v quiet -print_format json -show_format -show_streams yourfile.mp3