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layout: default title: Network Audio Receiver (UDP) for Raspberry Pi description: Lightweight UDP stereo audio receiver for Raspberry Pi with very low latency via ALSA and PipeWire. Developed in Free Pascal on Debian Bookworm.

🎶 Network Audio Receiver (UDP) for Raspberry Pi

A lightweight UDP stereo audio receiver for Raspberry Pi.
It outputs directly to ALSA (also compatible with PipeWire via ALSA emulation), ensuring very low latency – ideal for real-time monitoring and live audio.

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✨ Features

• Receives stereo audio over UDP (e.g., RTP stream) with selectable audio output: 3.5 mm jack, HDMI, USB, and more (choose one device at a time)
• Direct ALSA audio output for minimal delay
• Fully compatible with PipeWire via ALSA emulation
• Developed in Free Pascal using Codetyphon on Debian Bookworm
• No codec → uncompressed audio, maximum quality, minimal processing delay
• Supports multiple audio outputs: 3.5 mm jack, HDMI, USB, and more (selectable in settings)
• On startup, the window is visible
• If the “Start Minimized” checkbox is selected, the application will start minimized
• Lightweight with minimal dependencies (ALSA or PipeWire via ALSA)

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💡 Example Test Setup

• Sender: Raspberry Pi 4 or Pi 5 streaming audio over UDP
• Receiver: Raspberry Pi 4 or Pi 5 connected via Ethernet
• Output: 3.5 mm jack → HiFi amplifier, or HDMI/USB audio

Result: Stable low-latency playback on a typical home network, even while streaming video.

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▶️ 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

4. Save the file, place it on the desktop, and start it with a double-click.

📥 Receiver

Start the player:

./udp_player

• The player does not require sudo, as the necessary capabilities (cap_net_raw,cap_sys_nice+ep) are set during installation.
• On first start, it will create a configuration file at:

/var/lib/udp_player/udp_player.conf

• A window appears and starts playback automatically.
• Select the desired audio output in the settings window.
• Repeats the last valid audio block up to five times if new data is missing, preventing audible dropouts.

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⚙️ Settings Description

Control / Field	Description
Audio Output Selection	Choose the audio output device (Headphones/JACK, HDMI, USB audio, etc.). If no configuration exists for a device, a default configuration is created automatically at first start.
IP	IP address to receive audio from. Use 0.0.0.0 to listen on all network interfaces.
Port	UDP port for incoming audio. Default is 5010.
Frequency	Audio sample rate in Hz.
Latency	Audio latency in samples. Typical values: 22000 for JACK/Headphones, 4000 for USB audio.
Swap Byte Order	Enable this if the incoming audio uses a different byte order (big/little endian).
Hide Window	If enabled, the application window remains minimized or hidden once audio starts.
Test changes	This button immediately applies the current settings without saving them.
Save changes	This button saves the current settings to the configuration file for future use.
Delete Device	This button deletes the selected device configuration. If the device exists, it will be recreated with default values at the next program start.

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🎯 Latency Optimization

• Lower buffer size → lower delay
• Too low → possible dropouts or crackling audio
• Best settings depend on:
  • Network type (LAN allows lower latency than Wi-Fi)
  • Raspberry Pi performance
  • Audio hardware

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🔊 Audio Volume

If sound is too quiet:

alsamixer

• Press F6 to select the right device
• Raise the Master volume

Or via terminal:

amixer set 'Master' 100% unmute

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📦 Installation / Deinstallation via dpkg

Installation Steps

1. Copy the .deb package to your Raspberry Pi.

2. Install the package:

sudo dpkg -i udp_player_x.y.z.deb

This will install:

/usr/bin/udp_player         # Binary
/usr/share/applications/... # Desktop menu entry
~/.udp_player/              # Config folder (empty on first start)

Necessary capabilities are automatically set (cap_net_raw,cap_sys_nice+ep) → no sudo required for running the player.

3. Start the player:

udp_player 
or use the menu entry created during installation.

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Deinstallation Steps

To remove the player completely:

sudo dpkg -r udp_player

This removes the binary and the menu entry.

To also remove the config folder (if you want a clean uninstall):

rm -rf ~/.udp_player

📜 License

This project is licensed under the MIT License.

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🌐 Other Projects by the Author

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• DS18B20-FPC-Pi-GUI – GUI tool to read DS18B20 temperature sensors with linearization for high accuracy.
• RaspberryPi-BME280-GUI – Complete GUI application for accessing the BME280 I²C sensor using Free Pascal.
• RaspberryPi-GPIOv2-FPC – Simple and fast Pascal unit for controlling GPIO pins via the Linux GPIO character device interface.