Remove foreign languages from MKV file(s), e.g. Russian, Ukrainian, etc

remove-foreign-langs-from-mkv.sh

#!/bin/bash

set -euo pipefail

# Ensure mkvmerge is installed
if ! command -v mkvmerge &> /dev/null; then
    echo "Error: mkvmerge is not installed. Please install it first."
    exit 1
fi

# Ensure jq is installed
if ! command -v jq &> /dev/null; then
    echo "Error: jq is not installed. Please install it first."
    exit 1
fi

# Check if an input file is provided
if [ "$#" -lt 1 ]; then
    echo "Usage: $0 <input.mkv>"
    exit 1
fi

for INPUT_FILE in "$@"; do

	#OUTPUT_FILE="filtered_${INPUT_FILE}"
	TMP_DIR="$(dirname "${INPUT_FILE}")"
	OUTPUT_FILE="$(mktemp --suffix=.mkv --tmpdir="${TMP_DIR}")"
	
	echo "Processing: $INPUT_FILE"

	# Get track info from mkvmerge JSON output
	TRACKS_JSON=$(mkvmerge -J "$INPUT_FILE")

	audio_tracks=($(echo "$TRACKS_JSON" | jq -r '.tracks[] | select(.type == "audio" and (.properties.language == "eng" or .properties.language == "dut")) | .id'))
	subtitle_tracks=($(echo "$TRACKS_JSON" | jq -r '.tracks[] | select(.type == "subtitles" and (.properties.language == "eng" or .properties.language == "dut")) | .id'))

	echo "Remaining audio tracks: ${audio_tracks[@]}"
	echo "Remaining subtitle tracks: ${subtitle_tracks[@]}"

	# Prepare track arguments for mkvmerge
	track_args=()
	if [ ${#audio_tracks[@]} -gt 0 ]; then
	    track_args+=("-a" "$(IFS=,; echo "${audio_tracks[*]}")")
	fi
	if [ ${#subtitle_tracks[@]} -gt 0 ]; then
	    track_args+=("-s" "$(IFS=,; echo "${subtitle_tracks[*]}")")
	fi

	# Run mkvmerge to create the filtered file
	mkvmerge -o "$OUTPUT_FILE" --no-attachments "${track_args[@]}" "$INPUT_FILE"
	
	echo "Writing merged file back to $INPUT_FILE..."
	mv --force "$OUTPUT_FILE" "$INPUT_FILE"

	echo "Finished $INPUT_FILE"

done