MKV Subtitle Cleaner

A Python script that scans .mkv files and removes non-English subtitle tracks, keeping your media library clean and consistent.

It uses mkvmerge to safely rewrite files while preserving only allowed subtitle languages.

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What It Does

• Recursively scans one or more directories for .mkv files

• Detects subtitle tracks using mkvmerge

• Removes subtitles that are not in allowed languages (default: English)

• Tracks previously processed files to avoid unnecessary reprocessing

• Logs:

  • Processed files
  • Missing files
  • Files flagged during dry runs

• Supports a dry-run mode to preview changes without modifying files

• Displays progress using tqdm progress bars

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Pre-requisites

Make sure the following are installed:

1. Python

Python 3.7+ recommended

2. MKVToolNix

Provides mkvmerge, which is required.

Install via package manager:

# Ubuntu/Debian
sudo apt install mkvtoolnix

# Arch / Artix
sudo pacman -S mkvtoolnix-cli

3. Python Dependencies

Install required Python packages:

pip install tqdm

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Usage

Basic run:

python script.py

Force re-check all files:

python script.py --force-recheck

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Variables to Edit

You can configure behavior via environment variables or directly in the script.

Input Directories

INPUT_DIRECTORIES = os.getenv(
    "MKV_INPUT_DIRS",
    "/home/Movies/,/home/Movies2/,/home//Movies3/"
).split(",")

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Log Directory

LOG_DIRECTORY = os.getenv(
    "MKV_LOG_DIR",
    "/home/Program/scripts/Delete_subs/"
)

Stores:

• non_english_subs.log
• checked_files.log
• missing_files.log
• DRYRUN-Flagged.log

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Allowed Subtitle Languages

ALLOWED_SUB_LANGUAGES = ["eng", "en", "und"]

• Uses ISO language codes

Default keeps:

• eng → English
• en → English (alternative code)
• und → Undefined (often safe to keep)

Modify to suit your needs:

ALLOWED_SUB_LANGUAGES = ["eng", "jpn"]

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Dry Run Mode

DRY_RUN = False

• Set to True to simulate changes only
• No files will be modified
• Flagged files will be logged instead

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