pengchujin/jzsub

JZSub is a tool that takes a single video link and hands you back the highest quality version of that video, its cover image, and a version with two language subtitles burned directly into the picture. It works with YouTube, Bilibili, Vimeo, Twitch, Dailymotion, TikTok, and other sites supported by the yt-dlp download library, though what formats and subtitles are actually available depends on each platform. The tool downloads the best available video and audio streams and packages them into a nearly lossless MP4. For subtitles, it translates the source captions in small batches, keeping context between batches so the translation reads naturally, then splits the result back along sentence boundaries. The original subtitle text is never altered. By default it translates into Chinese, but you can set a different target language such as Japanese or French. The finished bilingual subtitles are burned into the video using a specific font, stacked at the bottom of the frame, with the layout adjusting automatically for vertical, portrait style videos. You choose what you actually want delivered: the full pipeline of video, cover, subtitles, and a burned in bilingual MP4, just the video plus any original subtitle file, just the raw subtitles, or only the bilingual subtitle files without downloading the video at all. If a platform has no subtitles, the tool still delivers the video, an MP4, and a cover image. JZSub is built to run as a Codex skill, a kind of plugin for the Codex coding assistant. You can install it with a single command through Codex's skill installer, or clone the repository and copy its skill folder into place manually. Once installed, you send a short command with a video link inside a Codex session and the tool handles downloading, translation, subtitle rendering, and final delivery on its own. Running it requires Python 3.10 or newer, the yt-dlp downloader, the Deno JavaScript runtime, FFmpeg built with subtitle rendering support, and a specific bold font that must be downloaded separately from Xiaomi's website. The author notes that JZSub only downloads content you already have the right to access, and does not bypass DRM, paywalls, captchas, or other platform protections. The project is released under the MIT license.