一字幕 is a free multimedia subtitle plugin that supports bilingual audio and video subtitles. It enables users to translate words, phrases, and entire sentences, supporting platforms like YouTube and Bilibili. Users can also add external subtitles or embed subtitles, adjust playback speed, repeat sections, follow along with subtitles, and block parts of the screen.

The main purpose of the design is to efficiently assist foreign language learners in acquiring new languages by utilizing online and local audio and video resources with the help of AI technology.

Key features include displaying bilingual subtitles in a list format for audio and video media resources, using shortcuts for various subtitle playback functions, translating unfamiliar words, phrases, and sentences, covering parts or all of the screen, and support for mainstream video platforms like YouTube, Bilibili, and Aliyun Drive.