AI Subtitle Annotator
Add pinyin, furigana, or romaji reading aids to your Chinese and Japanese subtitles. Perfect for language learners. AI-powered with your own API key.
Drag & drop your subtitle file here
Drag and drop subtitle files here or click to browse
Key Features
Engineered for video editors and localization teams. Helps enforce common subtitle timing rules and formatting.
AI Subtitle Annotator Live Execution Demo
Direct Provider Processing
File loading happens in your browser runtime; subtitle batches are sent directly to your chosen AI provider using your configured API key.
Millisecond Precision
Millisecond-accurate timecode parsing and arithmetic prevent synchronization drift across desktop and web players.
Fault-Tolerant Engine
Automatic multi-encoding detection and syntax sanitization gracefully handle malformed cues and unexpected linebreaks.
Common Use Cases
Real-world scenarios across video post-production, course transcription, and global localization.
Language Learning
Add pinyin to Chinese drama subtitles or furigana to anime subtitles for reading practice.
Karaoke Preparation
Add romaji to Japanese song subtitles so non-readers can sing along phonetically.
Study Materials
Create annotated subtitle files for language class materials or self-study.
Reading Support
Help learners who can speak but not read CJK characters by providing pronunciation guides.
Translation Review
Add readings to verify that subtitles match the spoken audio in tone and pronunciation.
Accessibility
Provide phonetic reading aids for viewers who are learning the language of the subtitles.
How It Works
Streamlined end-to-end processing pipeline engineered for speed and precision.
Upload & Import
Select your Chinese or Japanese subtitle file.
Format Analysis
Enter your OpenAI API key (get one at platform.openai.com).
Choose the annotation mode
Pinyin for Chinese, Furigana or Romaji for Japanese.
Processing
Select whether readings appear above the text or inline in parentheses.
Click Annotate
The AI processes subtitle text in batches to add reading aids.
Delivery
Download the annotated subtitle file in your chosen format.
Why Choose AllSubConverter?
Client-Side Privacy
Standard tools run in your browser so standard files are not uploaded to our servers.
Fast Local Parsing
Optimized processing engine parses and converts files directly in your browser.
Generous Batches
Up to 50 MB per file, 200 files or 1 GB total per batch.
Universal Compatibility
Runs in modern browsers across Windows, macOS, Linux, iOS, and Android.
More Subtitle Tools
Frequently Asked Questions
Yes. This tool uses your own OpenAI API key to generate annotations. You can get one at platform.openai.com. The key stays in your browser and is sent directly to OpenAI, never to our servers.
The AI uses context to determine correct readings, which handles most cases well. However, Chinese has many homophones and Japanese kanji has multiple readings, so some annotations may need manual review for uncommon proper nouns or rare characters.
Separate Line places the reading on a new line after the original text. Inline places the reading in parentheses after each word or character segment.
Pinyin is the romanization system for Mandarin Chinese (e.g. ni3 hao3). Furigana are small hiragana characters placed above kanji to indicate pronunciation. Romaji is the romanization of Japanese text (e.g. konnichiwa).
The tool is designed for Chinese and Japanese text. For Korean, you could use romaji mode, but accuracy may vary. English and other Latin-script text is passed through unchanged.
Input: SRT, VTT, ASS, SSA, LRC, SBV, TTML, SCC, STL, SMI. Output: SRT, VTT, or TXT (plain text with annotations only).
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