srtsyncfix.sh

srtsyncfix.sh is a small Bash utility that automatically synchronizes .srt subtitle files with their corresponding .mkv video files using ffsubsync. It scans a directory (or a single MKV file), finds matching SRTs, fixes their timing, and prevents repeated processing by adding a marker line to already‑synced subtitles.

The script is designed for media libraries where filenames may contain spaces, parentheses, brackets, or other special characters.

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Features

• Automatically finds .mkv files in a directory
• Matches .srt files based on the MKV basename
• Uses ffsubsync to correct subtitle timing
• Adds a marker line to avoid reprocessing already‑synced subtitles
• Safely handles filenames with spaces, brackets, parentheses, and unicode
• Removes macOS AppleDouble junk files (._*)
• Optional language filtering (e.g., eng, nld, pob)

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Requirements

1. ffsubsync

This is the core subtitle‑sync engine.

Install via pip:

pip install ffsubsync

Or, if using Python 3 explicitly:

pip3 install ffsubsync

2. Python 3

Required by ffsubsync.

Check:

python3 --version

3. Bash

The script uses Bash arrays, process substitution, and set -euo pipefail.

4. Standard Unix tools

These are available on all Linux distributions:

• find
• mv
• grep
• dirname
• basename
• printf
• mapfile

No additional packages required.

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Usage

Process the current directory

./srtsyncfix.sh .

Process a specific movie file

./srtsyncfix.sh "FERRARI (2023) - [1080p].mkv"

Process only a specific subtitle language

./srtsyncfix.sh . nld

This will only sync subtitles ending in .nld.srt.

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How it works

1. Removes AppleDouble files (._*)
2. Optionally strips leading/trailing quotes from filenames
3. Detects MKV files
4. For each MKV:
   • Finds matching SRT files
   • Skips SRTs already containing the marker line
   • Runs ffsubsync to generate a corrected subtitle
   • Backs up the original SRT
   • Replaces it with the fixed version
   • Appends a marker line:

     Fixed by ffs on YYYY-MM-DD HH:MM
     

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Backup behavior

Every processed subtitle is backed up automatically:

original.srt → original.srt.bck

This ensures you can always revert if needed.

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Notes

• The script does not modify MKV files.
• The script only processes .srt subtitles.
• The skip‑marker prevents expensive reprocessing.
• Filenames with quotes can be cleaned automatically if desired.

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If you want, I can also generate:

• a man‑page style README
• a GitHub‑ready README with badges
• a usage example section with real MKV/SRT filenames

Just tell me what style you prefer.