Delete duplicate external subtitles if embedded subtitles exist

delete_duplicate_subtitles.sh

#!/usr/bin/env bash

# Check if argument provided
if [ -z "$1" ]; then
  echo "Usage: $0 /path/to/media"
  exit 1
fi

BASE_DIR="$1"

# Mapping from 3-letter embedded codes to 2-letter external codes
declare -A EMBEDDED_TO_TWO_LETTER=(
    [eng]="en"
    [spa]="es"
    [ita]="it"
    [jpn]="ja"
    [fra]="fr"
    [ger]="de"
    [por]="pt"
    [rus]="ru"
    [chi]="zh"
    [kor]="ko"
    [swe]="sv"
    [pol]="pl"
)

# Find all mkv or mp4 files recursively
# Use `-print0` and `read -d ''` to properly handle filenames with spaces
find "$BASE_DIR" -type f \( -iname "*.mkv" -o -iname "*.mp4" \) -print0 | while IFS= read -r -d '' media_file; do
    # Get the directory containing this media file
    dir="$(dirname "$media_file")"
    filename="$(basename "$media_file")"
    base_name="${filename%.*}"

    # Move into that directory
    cd "$dir" || continue

    # Extract JSON info about the file
    json_info=$(ffprobe -v quiet -print_format json -show_streams "$filename")

    # Get all embedded 3-letter language codes from subtitles
    embedded_langs_3=$(echo "$json_info" | jq -r '.streams[] | select(.codec_type == "subtitle") | .tags.language' 2>/dev/null)

    # Convert embedded languages from 3-letter to 2-letter
    embedded_langs_2=()
    for lang3 in $embedded_langs_3; do
        if [ -n "${EMBEDDED_TO_TWO_LETTER[$lang3]}" ]; then
            embedded_langs_2+=("${EMBEDDED_TO_TWO_LETTER[$lang3]}")
        else
            # If code not in map, we skip it
            continue
        fi
    done

    declare -A embedded_map
    for l2 in "${embedded_langs_2[@]}"; do
        embedded_map["$l2"]=1
    done

    # Process all external subtitles (srt/ass/vtt) that match the base name
    for subfile in "$base_name".*.srt "$base_name".*.ass "$base_name".*.vtt; do
        # Check if file exists (the pattern may fail)
        [ -e "$subfile" ] || continue

        # Extract the two-letter language code from something like base_name.en.srt
        lang_code=$(echo "$subfile" | sed -E 's/.*\.([a-zA-Z0-9]{2})\.[^.]+$/\1/')

        # If this two-letter code matches an embedded language, disable it
        if [ -n "${embedded_map[$lang_code]}" ]; then
            echo "Disabling external subtitle: $subfile"
            mv "$subfile" "$subfile.disabled"
        fi
    done

    # Clean up
    unset embedded_map
done