Network Audio Receiver (UDP) for Raspberry Pi (FPC)

UDP network audio receiver for Raspberry Pi with very low latency via ALSA.

The program automatically detects whether packets are being received:

• If packets arrive → audio is played.
• For maximum quality, no codec is used – the audio is transmitted uncompressed.
• This allows for very low latency, making it ideal for real-time transmissions (e.g., monitoring, live audio).
• A separate settings window is available.
• If the “Start Minimized” checkbox is selected, the application will start minimized.
• A startup script for an FFmpeg audio sender (StartFFmpegTransmitter.sh) is provided. Place it on the desktop and start it with a double-click.

---

💠 Requirements

• Raspberry Pi running Debian Bookworm
• ALSA installed
• Network connection for receiving UDP packets

---

🧪 Test Setup

Example setup used during development and verification:

• Sender: Raspberry Pi 4 playing YouTube videos in a browser, connected via 2.4 GHz Wi-Fi to a router.
• Receiver: Another Raspberry Pi 4, connected via Ethernet (LAN) to the same router.
• Receiver’s 3.5 mm jack audio output connected to a HiFi receiver for playback.

This setup demonstrated stable low-latency streaming under typical home network conditions.

---

▶️ Usage

📤 Sender (System Audio)

Install ffmpeg:

sudo apt install ffmpeg

To transmit system audio, use the provided startup script StartFFmpegTransmitter.sh:

1. Edit the script and replace the IP address with the address of your receiver.
2. Set the port number to match the configuration on the receiver.
3. Make the script executable:

   chmod +x StartFFmpegTransmitter.sh
   
    Save the file, place it on the desktop, and start it with a double-click.
   

📥 Receiver

Start the player:

./udp_player

A window appears and starts playback automatically when UDP packets arrive.

---

📥 Receiver

Start the receiver:

./udp_player

The receiver window will appear and automatically start playing audio when UDP packets are received.

Silence Handling:
If no audio packets—or only silent packets—are received for 5 seconds, the ALSA output is stopped and released. When new packets arrive, ALSA is automatically re-initialized, allowing playback to resume seamlessly.

---

🎯 Optimization Notes

Audio latency can be configured in the receiver application:

• Lower latency values → reduce audio delay, improving real-time performance.
• Too low values → may cause sporadic audio dropouts, depending on network type and stability.
• Extremely low values → may result in distorted or crackling audio due to buffer underruns.

Optimal settings depend on:

• Network quality and stability
• Connection type (LAN generally allows lower latency than Wi-Fi)
• Performance of the Raspberry Pi and audio output hardware

---

🔊 If the audio is too quiet

This may occur if the receiver volume is set too low.

Possible solutions:

• Use alsamixer, press F6 to select the correct device, and increase the volume
• Or via terminal:

amixer set 'Master' 100% unmute

---

📝 License

This project is licensed under the MIT License.