Video Merger Tool

A browser-based tool that allows you to merge two videos vertically - with the color video on top and the mask video on the bottom.

Features

• Upload and merge two videos with ease
• Client-side processing (no server uploads needed)
• Support for both MP4 and MOV input formats
• Output as MP4 with combined height
• Responsive design that works on various screen sizes

Demo

Access the live demo at this Page

How It Works

This tool uses FFmpeg.js to process and merge videos entirely in your browser. When you upload two videos, it:

1. Converts both videos to a compatible format
2. Stacks them vertically using the vstack filter
3. Provides a preview and download link for the merged video

Use Cases

• Combining instructional content with demonstrations
• Creating before/after video comparisons
• Merging synchronized video footage from different angles
• Making split-screen presentations

Requirements

• Both videos should have the same length, resolution, and aspect ratio
• Works best with modern browsers (Chrome, Firefox, Edge)
• Requires browser that supports WebAssembly

Local Development

Running the app locally

1. Clone this repository
2. Run a local web server (Python example below)

python3 -m http.server 8000

Or use the included server with CORS headers for better compatibility:

python3 server.py

3. Open your browser to http://localhost:8000 or http://localhost:9999 (if using server.py)

Browser Compatibility

This tool requires a modern browser with WebAssembly support. For best results:

• Use Chrome, Firefox, or Edge
• Safari may have limited compatibility
• Enable JavaScript

Limitations

• Processing large videos may be slow or cause browser memory issues
• Maximum video resolution depends on your device's capabilities
• Both videos must have the same width for optimal results

License

MIT License

Credits

• FFmpeg.js - WebAssembly port of FFmpeg