
# The Project

This project is a small experiment to capture and transcribe in real time an audio stream from a radio station (RAC1) and display the most relevant fragments using a minimalist web interface. All of it is automated with Docker.

It's also a personal *vibe coding* test, done with a clear goal but no prior planning—just following intuition to see how far one can accelerate development. Although the project works, I acknowledge that with this process you lose part of the pleasure of structured knowledge and planning, which would make the solution more robust and scalable.

This fast and improvised way of coding tends to skip certain abstractions and structures that are often what enable deeper creativity: the kind that emerges when tools not only work, but you understand *why* they work.

## Access the Demo

👉 Try it: [https://eurekatop.com/radioalert](https://eurekatop.com/radioalert)  
👉 SSE Endpoint: [https://eurekatop.com/radioalert/events](https://eurekatop.com/radioalert/events)

<img
  src="/images/radio-alert-content-1.png"
  alt="Image description"
  style={{ alignSelf: 'center', width: '80%', maxWidth: '80%', height: 'auto', borderRadius: '12px' }}
/>

## Backend: Automatic Transcription with Whisper

The core of the project is a Python script that listens to the stream as if it were a browser. At first, I tried using `ffmpeg` to capture the stream, but it failed because the station has anti-bot protections and the connection was not accepted.

As an alternative, I found that using `httpx.stream()` allows reading the audio stream without issues—as long as the request looks like a real browser's. That’s why you need to add some headers...

The script is split into two parts: one for capturing the stream and another for transcription and keyword filtering. This transcription runs in parallel with the stream capture, so there's no need to wait for it to finish before continuing to capture.

The audio is processed in 4-second chunks and transcribed using the optimized *Whisper* model (`int8`).

```python
model = WhisperModel("/models/whisper-small", compute_type="int8")
segments, _ = model.transcribe(BytesIO(audio_data), language="ca")
```

Once transcribed, it checks for keywords like “barça”, “avui”, or “lamine yamal”. If any are found, it triggers an alert and logs everything to a `.log` file. For example:

🕒 [2025-06-09 14:10:23] 🗣️ [12] avui a catalunya hem vist que...  
🚨 🕒 [2025-06-09 14:10:23] ALERT: Keyword detected: avui

The system includes a short queue of previous audio to avoid cutting off sentence beginnings, since the model needs context to understand the stream correctly.

All of it is automated with Docker.

## Frontend: Live Visualization

A small Node.js server displays the transcribed lines live from a `.log` file, sending them via Server-Sent Events to the terminal-style web interface.

```js
fs.readFile(FILE_PATH, 'utf8', (err, data) => {
  const lines = data.trim().split('\n').slice(-30)
  lines.forEach(line => res.write(`data: ${line}\n\n`))
})
```

On the client side, the connection remains open with the browser's `EventSource()`, which automatically receives real-time updates:

```js
const eventSource = new EventSource('/events')
eventSource.onmessage = function(event) {
  console.log(event.data)
}
```

---

## 💡 Learnings

- Whisper is quite reliable, even in Catalan.
- Adding a buffer of previous audio improves accuracy in clipped sentences.
- With `httpx.stream` and lightweight threads, you can capture audio stably without overloading the main process. `ffmpeg` was initially used but discarded to avoid anti-bot protections by simulating a real browser connection.
- Server-Sent Events are a very simple yet effective tool to stream live data to a web app.

## Stack and Techniques

- 🐍 Python + [faster-whisper](https://github.com/guillaumekln/faster-whisper)
- 📡 httpx for capturing audio streams
- 🎛️ Catalan transcription with the optimized Whisper-small model
- 🐳 Docker to encapsulate the service
- 🟩 Node.js + Express to expose the file as an SSE feed
- 🎨 HTML + CSS in terminal-console style

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A vibe coding experiment by Francesc López Marió, 2025


A small experiment that captures and transcribes a radio stream in real time using Whisper, and displays the keywords on a retro-style web interface.

Category: transcription