Linux Display Audio Keepalive

A systemd user service that prevents HDMI/DisplayPort audio from cutting out by maintaining a silent audio stream.

The Problem

Many displays, monitors, and AV receivers aggressively power down their audio processing when no sound is playing. This causes several annoying issues:

• First sound cutoff: The first 0.5-2 seconds of audio gets lost when playback starts after silence
• Audio pops/clicks: Audible artifacts when the audio hardware wakes up
• Delayed audio start: Noticeable lag before sound begins playing
• Periodic dropouts: Some devices (especially those with One Connect boxes) drop audio for 1-2 seconds periodically

This happens because HDMI and DisplayPort embed audio in the video signal. When audio stops, the receiver's DAC and audio processing circuitry enter sleep mode. Re-initialization takes time, causing the symptoms above.

Samsung Odyssey Ark 2nd Gen / One Connect Box

The Samsung Odyssey Ark 2nd Gen with its One Connect Box is particularly affected by this issue:

• Periodic audio drops: Users report sound cutting out for 1-2 seconds approximately every 45-60 minutes
• External source issues: The problem primarily affects devices connected via the One Connect Box's HDMI ports, while internal apps work fine
• Dolby Digital processing: There appears to be an issue with how the One Connect Box processes Dolby Digital signals from external sources
• Audio delay: Some users experience ~200ms audio delay when using eARC with external receivers
• Signal renegotiation: The One Connect Box may trigger HDMI/DP link renegotiation during periods of silence, causing brief audio interruptions

The One Connect Box acts as an intermediary between your PC and the display, and its power management behavior can be more aggressive than direct connections. This service works around these issues by ensuring continuous audio data flow.

Related Samsung Issues

These problems have been reported across multiple Samsung devices with One Connect boxes, including:

• Samsung Odyssey Ark (1st and 2nd Gen)
• Samsung The Frame series
• Samsung QLED TVs (Q95TD and similar)
• Samsung S95C/S95D OLED TVs with eARC

How It Works

The service uses pacat to continuously stream silence to the audio output. This works with both PulseAudio and PipeWire (via pipewire-pulse compatibility).

pacat -p --rate=48000 --channels=2 --format=s16le /dev/zero

Parameter	Purpose
-p	Playback mode
--rate=48000	48kHz sample rate (standard for HDMI audio)
--channels=2	Stereo output
--format=s16le	16-bit signed little-endian PCM
/dev/zero	Source of silence (continuous zeros)

This keeps the audio link active without producing audible sound, preventing the receiver from entering sleep mode.

Requirements

• Linux with systemd
• One of the following audio tools:
  • pulseaudio-utils (recommended): provides pacat, works with both PulseAudio and PipeWire
  • pipewire-utils (alternative): provides pw-cat for native PipeWire

The installer automatically detects which tool is available.

Installing Dependencies

Fedora:

sudo dnf install pulseaudio-utils

Ubuntu/Debian:

sudo apt install pulseaudio-utils

Arch Linux:

sudo pacman -S libpulse

Installation

Quick Install (curl)

curl -fsSL https://raw.githubusercontent.com/DigitalCyberSoft/linux-display-audio-keepalive/main/install.sh | bash

Or clone and run:

git clone https://github.com/DigitalCyberSoft/linux-display-audio-keepalive.git
cd linux-display-audio-keepalive
./install.sh

Manual Installation

cp hdmi-keepalive.service ~/.config/systemd/user/
systemctl --user daemon-reload
systemctl --user enable --now hdmi-keepalive.service

Uninstallation

./install.sh --uninstall

Or manually:

systemctl --user disable --now hdmi-keepalive.service
rm ~/.config/systemd/user/hdmi-keepalive.service
systemctl --user daemon-reload

Verifying It Works

Check service status:

systemctl --user status hdmi-keepalive.service

Verify the silent stream is active:

pactl list clients | grep pacat

Troubleshooting

Service fails to start

Ensure pacat is installed:

which pacat

Audio still cuts out

The service streams to the default audio sink. If you have multiple audio outputs, you may need to modify the service file to target a specific sink.

Find your sink name:

pactl list sinks short

Then edit ~/.config/systemd/user/hdmi-keepalive.service and add --device=YOUR_SINK_NAME to the ExecStart line.

High CPU usage

This service should use negligible CPU (<0.1%). If you see high usage, check for other audio issues or try restarting PulseAudio/PipeWire.

License

MIT License - Use freely, modify as needed.