better-ai-srt-translation/README.md

SRT Translator

A powerful, browser-based tool for translating SRT subtitle files using AI. Built for speed, accuracy, and ease of use.

🎯 What Problem Does It Solve?

Translating subtitles is tedious and expensive:

• Manual translation is slow and costly
• Generic AI translation loses subtitle timing and structure
• Existing tools don't handle the unique challenges of SRT format (split sentences, timing markers, etc.)

SRT Translator solves this by:

1. Preserving all timestamps exactly as-is
2. Using a smart marker system to maintain line-by-line correspondence
3. Processing chunks in parallel for maximum speed
4. Allowing custom instructions for domain-specific terminology

✨ Features

• Drag & Drop - Just drop your SRT file and go
• 50 Parallel Requests - Blazing fast translation
• Smart Chunking - Processes 75 subtitle blocks per request for optimal speed/accuracy balance
• Marker-Based Alignment - Each subtitle block stays aligned with its timestamp
• Custom Instructions - Add context-specific translation rules (e.g., "Use informal 'sen' instead of formal 'siz'")
• Custom Model Support - Use any model available on OpenRouter
• Multi-Language - Translate to 15+ popular languages
• Real-Time Progress - Visual feedback for each chunk's status
• Retry with Backoff - Automatic retry on failures

🚀 Quick Start

1. Open index.html in your browser
2. Enter your OpenRouter API key
3. Drop an SRT file
4. Select target language
5. Click "Translate"
6. Download your translated SRT

⚙️ Configuration

Setting	Default	Description
Model	google/gemini-3-flash-preview	AI model for translation
Chunk Size	75	Number of subtitle blocks per API request
Parallel Requests	50	Maximum concurrent API calls

Recommended Model

For the best performance/cost balance, we recommend:

google/gemini-3-flash-preview

This model offers:

• Fast response times
• Excellent instruction following
• Great translation quality
• Cost-effective pricing

Other options:

• google/gemini-2.5-flash-lite - Budget option, may have lower accuracy

🧠 How It Works

The Marker System

Traditional AI translation loses track of which text belongs to which subtitle block. We solve this with markers:

Input to AI:

[B1] I don't think OpenAI will
[B2] be around in 5 years.
[B3] They're burning cash.

AI Output:

[B1] OpenAI'ın var olacağını
[B2] 5 yıl içinde sanmıyorum.
[B3] Paralarını yakıyorlar.

Each [B#] marker ensures the translated text maps back to the correct timestamp.

Translation Priority

1. Line Structure (Mandatory) - Each marker line stays separate
2. Natural Translation - Idiomatic, not word-for-word
3. Word Count (Soft) - Similar length per line when possible

📁 Project Structure

srt-translator/
├── index.html          # Main UI entry point
├── README.md           # Documentation
├── src/
│   ├── app.js          # Core application logic
│   └── styles.css      # Dark theme styling
└── assets/
    └── ui.webp         # UI screenshot

🔧 Custom Instructions Examples

Turkish informal:

Türkçe çeviride "siz" yerine "sen" formu kullan.

Technical content:

Keep technical terms like "API", "SDK", "cache" untranslated.

YouTube tone:

Use casual, engaging language suitable for YouTube videos.

📝 API Requirements

• Provider: OpenRouter
• API Key: Get one at https://openrouter.ai/keys
• Models: Any chat completion model on OpenRouter

🛡️ Privacy

• Your API key is stored locally in your browser (localStorage)
• SRT files are processed client-side
• Only subtitle text is sent to the AI API
• No data is stored on any server

📄 License

GPL-3.0 License

Built with ❤️ for content creators who need fast, accurate subtitle translations.