Captionify — AI Video Caption Generator Subtitle Editor Flutter App

Flutter Mobile App + Python Backend for AI Video Subtitles

Captionify is a complete Flutter mobile app with a Python backend that allows users to upload videos, generate subtitles, translate subtitle text, customize subtitle styles, and export a final MP4 video with burned-in subtitles.

This item includes the Flutter mobile app source code, Python Flask backend source code, and setup documentation.

Main Highlights

• AI-powered video subtitle generation
• 99+ transcription languages supported by Whisper
• 130+ subtitle translation target languages supported by Google Translate integration
• Flutter mobile app source code included
• Python Flask backend source code included
• One-time purchase
• APK preview available before purchase

Key Features

• AI Transcription: Generate subtitles from video or audio using faster-whisper.
• Subtitle Translation: Translate generated subtitle text into multiple languages using Google Translate integration.
• Subtitle Styling: Customize font size, subtitle color, background color, opacity, position, bold style, and italic style.
• MP4 Export: Export final videos with burned-in styled subtitles.
• Flutter Mobile App: Android and iOS source code with onboarding, Firebase authentication, profile, history, and editor screens.
• Python Backend: Flask REST API with FFmpeg audio extraction, transcription, translation, and SRT subtitle generation.
• Local History: Keep previously generated subtitle projects in the app.
• Light and Dark Mode: Clean UI with theme support.

How It Works

1. Upload Video: Select a video from the gallery or record a new video using the camera.
2. Process Video: FFmpeg extracts audio and faster-whisper generates subtitle text.
3. Customize Subtitle Style: Adjust subtitle colors, size, opacity, and position.
4. Export MP4: Save the final video with burned-in subtitles.