Vernoxvernax / font-ass_tool

Utility to easily batch through ass subtitle files and collect dependent fonts.

Font-Ass_Tool

A simple small utility to mux a subtitle file with its font dependencies into a Matroska-Container

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Installation:

Linux:

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Make sure you have the following software already installed:

• fontconfig
• FFmpeg
• cargo + rust

cargo install --path .
export PATH="$HOME/.cargo/bin:$PATH"

Windows (by compiling and linking to fontconfig):

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Make sure you have some version of Visual Studio installed (tested with 2022 Community).

Additional requirements:

• meson
• ninja
• git
• FFmpeg
• cargo + rust (for compiling)
• brain

Read and run build_fontconfig.bat.

Now run cargo build --release.

Read and run copy_dlls.bat (unless you want to add three different folders to your path).

Any tips on how to improve the dll situation are very welcome.

Dlopen:

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I don't really know (or care) what this feature is supposed to be useful for, but it requires pkg-config. So pretty painful to set up on Windows (MSYS).

Usage:

fa_tool check subtitle.ass
fa_tool run subtitle.ass

Replace fa_tool with cargo run --release -- when on Windows.

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Notes:

This script parses the subtitle file, asks fontconfig for a matching font and muxes them into one file.

• The mkv output is not a playable file, it's only made for an easier remuxing progress. (MPV options like external-file are not supported)
  • This affects all FFmpeg based applications. If your subtitle file doesn't start at time 0, it won't play as expected. (MPV will always skip to the beginning of the first track)
  • Hint: put a video track into the container, or play the subtitle file externally
• FFmpeg is run with overwrite disabled by default.

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Problems:

I got angry, learned C++ and searched GitHub. After a while I found that Aegisub's font collector almost perfectly matches all font names you feed into it, so I decided to translate parts of it's font_file_lister_fontconfig.cpp file to rust. We thus also finally have "warnings" when a font couldn't be found. (indicated by the font path = Not found).

This code should be able to handle all correctly formatted ASS subtitle files.

If there is anyone who knows how to get a correct match for fonts like Bahnschrift, then please create an issue, or reach out to me on Discord!

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