How to Communicate with nymphcast_server from a Custom App (React Native)

[ayushbharadva]

📡 How to Communicate with nymphcast_server from a Custom App (React Native Feature)

Hi NymphCast team and @MayaPosch 👋,

First off, thank you for this fantastic project! It's an amazing concept, and I’m really excited to integrate it into my react-native app setup.

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✅ What I’ve Got Working

• I’m able to run nymphcast_server (v0.1) on my Windows 11 PC.
• When using the official NymphCast Android app, everything works smoothly — I can successfully cast media from my phone to the PC.

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🎯 What I Want to Achieve

I already have a React Native app — it’s similar to a Google Home-style app, where users can control their smart appliances over the local network.

Now, I want to add a feature that allows users to:

• Discover available cast targets on the local network
• Select a device and cast MP3 files from the phone to it
• Control playback (play, pause, stop)

Eventually, this feature is intended to work with Wi-Fi speakers. But for testing purposes, I’m using my PC, where I’ve set up nymphcast_server to simulate a castable speaker device.

So instead of building a separate NymphCast client, I want to integrate this casting functionality directly into my existing react-native app.

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❓ What I Need Help With

I’d really appreciate some guidance on:

• 📡 What protocol does nymphcast_server expect?

  • Is there a public protocol specification or message format?
  • How should commands like PLAY, PAUSE, or STOP be structured?

• 💡 Are there any example scripts or tools (in Python, JavaScript, etc.) that demonstrate sending commands to the server?

The client and server are written in C++, and I have a very basic understanding of C++, it’s been difficult to figure out how communication is handled.

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🙏 Why I’m Asking

Having a clear way to interact with the NymphCast server from a custom controller would be incredibly helpful — especially for integration into mobile react-native apps like mine.

Any protocol info, examples, or pointers would be deeply appreciated.

Thanks again for your amazing work on this open-source project!

[MayaPosch]

Hello @ayushbharadva

The easiest way to integrate NymphCast support is by using the libnymphcast project: https://github.com/MayaPosch/libnymphcast

This is a C++ library with a C binding also available. Please let me know if this is an acceptable solution for you.

[ayushbharadva]

Appreciate the guidance, @MayaPosch.

Yes, libnymphcast with C bindings appears to be a promising direction.
To proceed effectively, I’d like to clarify a few key points:

1. Is there a minimal example of using the C bindings to:

   • Discover available servers
   • Establish a connection
   • Cast a local file or a streaming URL
   • Control playback (pause, resume, stop)

2. Does the library expose any functionality to retrieve playback status or media metadata (e.g., title, artist, album art)?

3. From your experience, is it advisable to use a C++/C shared library bridge on Android to expose these capabilities to a React Native app, or is there a better abstraction route you’d recommend?

4. Once the receiver is connected, is it limited to casting only local media, or can it also accept streams from external apps (e.g., Spotify, Apple Music, YouTube) as a unified output target?

Looking forward to your insights to better align the implementation roadmap with NymphCast’s strengths.