Raspberry-UDP_audio_receiver

🎶 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 using its ALSA bridge), ensuring very low latency – ideal for real-time monitoring and live audio.

✨ 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 (PipeWire ALSA bridge supported)
Developed in Free Pascal using Codetyphon on Debian Bookworm
No codec → uncompressed audio, maximum quality, minimal processing delay
On startup, the window is visible
If the “Start Minimized” checkbox is selected, the application will start minimized
Settings can be activated immediately without saving
Separate settings window for device configuration

⚙️ Settings Overview (Form2)

Control / Field	Description
Audio Output Selection	Choose the audio output device (3.5 mm jack, HDMI, USB, etc.). If no configuration exists for a device, a default configuration is created automatically at program start. Only one device can be selected at a time.
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`.
Network Buffer	Size of the receive buffer in bytes. Must be at least as large as a single sent audio block.
Frequency	Audio sample rate in Hz (e.g., 48000).
Latency	Audio latency in samples. Typical values: 22000 for JACK/Headphones, 3000 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.
Activate	Immediately applies the current settings without saving them.
Save	Saves the current settings to the configuration file for future use.
Delete Device	Deletes the selected device configuration. If the device exists, it will be recreated with default values at the next program start.

💡 Example Test Setup

Sender: Raspberry Pi 4 or Pi 5 streaming YouTube audio via Wi-Fi
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 in a typical home network.

📥 Receiver

Start the player:

./udp_player

A window appears and starts playback automatically when UDP packets arrive. Audio output selection: If this is the first run or no previous configuration was selected, choose your desired audio output (3.5 mm jack, HDMI, USB, etc.) in the settings window.

Silence Handling:

If no audio packets arrive for 5 seconds, ALSA stops and releases the output.
Playback resumes automatically when new packets arrive.

📤 Sender (System Audio)

Install ffmpeg:

sudo apt install ffmpeg

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

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

chmod +x StartFFmpegTransmitter.sh

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

🎯 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

🔊 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

📜 License

This project is licensed under the MIT License.

🌐 Other Projects by the Author

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RaspberryPi-BME280-GUI – Complete GUI application for accessing the BME280 I²C sensor using Free Pascal.
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