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VobSub Image Extractor and OCR

This is a Python program designed to extract images from VobSub (.sub/.idx) files and convert them to text using OCR (Optical Character Recognition).

The extraction of the VobSub as been taken from SubtitleEdit and ported to python.

Features

1. Image Extraction: The program can extract images from provided VobSub files. The user can specify the file and destination folder for the extracted images.

2. OCR Processing: The program can use OCR to convert pre-extracted images to text. It supports multiple languages and uses different models for different languages. Specifically, it uses the MangaOcr model for Japanese (ja) and easyocr.Reader for other languages.

3. Flexible Modes: The program offers flexibility in its operation. Users can choose to only extract images from VobSub files, only perform OCR on existing images, or both.

4. [Not fully tested] Parallel Processing: The program allows the user to specify the number of jobs to run in parallel for image extraction, speeding up the process for large files.

Installation and Setup

Before running this program, it's recommended to create a virtual environment. This helps to isolate the project and avoid conflicts with dependencies of other projects. Here's how you can do it:

Creating a virtual environment

Using venv:

# Create a virtual environment
python3 -m venv env

# Activate the virtual environment
source env/bin/activate  # On Windows, use `.\env\Scripts\activate`

Using conda:

# Create a virtual environment
conda create --name myenv

# Activate the virtual environment
conda activate myenv

Replace myenv with any name you like for your environment.

Installing Dependencies

The next step is to install the necessary dependencies. These dependencies are listed in a file named requirements.txt.

pip install -r requirements.txt

Ensure you're still within your virtual environment when you run this command.

Usage

The program can be used from the command line as follows:

python script.py -m <mode> -s <sub_file> -d <destination_folder> -l <language> -j <jobs>

The arguments are:

• -m or --mode: Mode of operation. 'extract' to only extract images, 'predict' to only perform OCR on existing images, 'both' to extract and then perform OCR. Default is 'both'.
• -s or --sub-file: Path to the VobSub (.sub) file to process. This argument is required.
• -d or --destination-folder: Directory where the extracted images should be stored or where to find images for OCR, depending on the mode. This argument is required.
• -l or --language: The language(s) of the subtitles. If 'ja', MangaOcr model will be used. If 'other', easyocr.Reader will be used. Can be a list of languages. Default is 'ja'.
• -j or --jobs: Number of jobs to run in parallel for image extraction. Only applies in 'extract' and 'both' modes. Default is 1.

Extract .sub/.idx Files using mkvmerge and mkvextract

1. Download and install MKVToolNix

   You can find it here: MKVToolNix download page

2. Rip DVD to MKV

   You can use a tool like MakeMKV to rip your DVD into an MKV file. The process is usually straightforward: insert your DVD, open MakeMKV, and follow the on-screen instructions.

3. Identify the subtitle track

   Use the mkvmerge tool to identify the subtitle track in the MKV file. Open a terminal window and type the following command:

   mkvmerge -I yourfile.mkv

   This will list all tracks in the file. Look for lines that begin with Track ID. Note down the track ID of the subtitle track you're interested in.

4. Extract the subtitle track

   To extract the subtitle track, use mkvextract. Replace # with the track ID from the previous step. The command looks like this:

   mkvextract yourfile.mkv tracks track_id:outputfile.sub

   This will extract the subtitle track into outputfile.sub. If the subtitle track is in VobSub format, an additional outputfile.idx file will also be created.

Remember, the paths yourfile.mkv and outputfile.sub should be replaced with the appropriate paths and filenames on your system.