💾 Copus - MP3 to Opus/Ogg Converter

Copus is a lightweight web app that lets you convert MP3 files to Opus or Ogg formats directly in your browser. It's built with Node.js, Express, ffmpeg, and a simple frontend for drag-and-drop file conversion.

⚙️ Features

• Drag-and-drop or click-to-upload MP3 files

• Convert MP3 to Opus or Ogg formats

• Shows file size and conversion progress

• Download the converted file instantly

• Simple, responsive, and lightweight UI

• CORS enabled for flexible use

👨‍💻 Tech Stack

• Backend: Node.js, Express, Multer, ffmpeg

• Frontend: HTML, CSS, JavaScript

• File handling: Multer for uploads, Fluent-ffmpeg for audio conversion

• Deployment: Can run locally or on platforms like Render

✨ Getting Started

Prerequisites

• Node.js (v18+)

• ffmpeg installed and available in PATH

Installation

Clone repo

git clone https://github.com/loag0/copus.git
cd copus

Install dependencies

npm install

Running Locally

Tip

Install nodemon for live server reloading

npm install -g nodemon

Start server

nodemon index.js

Otherwise use

node index.js

Open your browser and go to:

http://localhost:3000

⚠️ Make sure you have ffmpeg installed; Copus uses it for file conversion.

📁 Folder Structure

copus/
│
├─ index.html
├─ index.js           # backend server
├─ package.json
├─ styles.css         # frontend styles
├─ script.js          # frontend logic
├─ assets/            # images, icons, favicon
│   ├─ upload.svg
│   └─ favicon.ico
└─ uploads/           # temporary uploaded files (auto-deleted after conversion)

Usage

• Open the app in your browser.

• Drag-and-drop or click to upload an MP3 file.

• Select the target format (Opus or Ogg).

• Click Convert.

• Download the converted file.

• Security & Performance Notes

• Temporary files are deleted after conversion.

• Only MP3 files are allowed for upload.

• CORS is enabled for frontend flexibility.

For production deployment, consider:

• Using HTTPS

• Limiting max upload size

• Rate limiting endpoints

• Running ffmpeg in a sandbox/container

⬆️ Deployment

You can host it on Render, Vercel, or any Node.js compatible server.

Make sure the server is accessible via HTTPS for secure file uploads/downloads.

Recognition

This project was inspired by @disara7, whose image format converter gave me the idea to make my own tool. I built copus to convert MP3s to Opus/OGG for my custom notification sounds, and now anyone can use it too!

🪪 License

MIT License — feel free to use, modify, or share.