README.en.md

ASS Tools

中文 | English

ASS Tools is a collection of utilities for processing and optimizing Advanced Substation Alpha (.ass) subtitle files.

Developed and maintained by MontageSubs, this toolkit focuses on advanced subtitle effects, specifically optimizing vector drawing tags and managing embedded resources.

File Structure

ass-tools/
├── scripts/
│   └── python/              # Python Scripts
│       ├── ass-drawing-subsetter.py
│       └── ass-font-extractor.py
├── LICENSE                  # MIT License
└── README.md                # Chinese Documentation
└── README.en.md             # English Documentation

Scripts

ass-drawing-subsetter.py

Description

Extracts vector drawing commands (\p1, etc.) from an ASS file and converts them into a subsetted, embedded TrueType font (TTF).

• Size Optimization: Replaces heavy and redundant drawing tags with lightweight font character calls.
• Subsetting: Uses FontTools to ensure the smallest possible font file size by including only required glyphs.
• Automation: Handles SSA-standard UUEncoding and updates the [Fonts] section automatically.

Usage

$ python ass-drawing-subsetter.py input.ass

Note: The optimized file will be saved as <filename>_optimized.ass.

ass-font-extractor.py

Description

A diagnostic tool designed to extract and decode embedded TrueType fonts (TTF) from ASS files using the SSA UUDecode algorithm.

• Validation: Useful for verifying glyphs after optimization.
• General Extraction: Decodes and restores any font embedded in the [Fonts] section.

Usage

$ python ass-font-extractor.py optimized_subtitle.ass

Dependencies

• Python 3.x
• FontForge (with Python extension)
• FontTools (pip install fonttools)

Community

Join our discussion groups for subtitle tech support, feedback, or collaboration:

• Telegram: MontageSubs
• IRC: #MontageSubs (Synced with Telegram)

License

Source code and documentation are licensed under the MIT License.

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