{{Short description|Software that manages audio devices}} {{About|a form of computer program that runs in the background|computers that stream audio over a network|media server}} {{inline |date=January 2025}} A '''sound server''' is software that manages the use of and access to audio devices (usually a sound card). It commonly runs as a background process.

== Sound server in an operating system== thumb|right|Description of layers that uses a Sound Server In a Unix-like operating system, a sound server mixes different data streams (usually raw PCM audio) and sends out a single unified audio to an output device. The mixing is usually done by software, or by hardware if there is a supported sound card.

===Layers===

The "sound stack" can be visualized as follows, with programs in the upper layers calling elements in the lower layers<ref>{{Cite web |title=Professional audio - ArchWiki |url=https://wiki.archlinux.org/title/Professional_audio |access-date=2026-02-27 |website=wiki.archlinux.org}}</ref>:

* Applications (e.g. mp3 player, web video) * Sound server (e.g. aRts, ESD, JACK, PulseAudio, PipeWire) * Sound subsystem (described as kernel modules or drivers; e.g. OSS, ALSA) * Operating system kernel (e.g. Linux, Unix)

=== Motivation ===

Sound servers appeared in Unix-like operating systems after limitations in Open Sound System were recognized. OSS is a basic sound interface that was incapable of playing multiple streams simultaneously, dealing with multiple sound cards, or streaming sound over the network.

A sound server can provide these features by running as a daemon. It receives calls from different programs and sound flows, mixes the streams, and sends raw audio out to the audio device.

With a sound server, users can also configure global and per-application sound preferences.

=== Diversification and problems ===

{{As of | 2012}} there are multiple sound servers; some focus on providing very low latency, while others concentrate on features suitable for general desktop systems. While diversification allows a user to choose just the features that are important to a particular application, it also forces developers to accommodate these options by necessitating code that is compatible with the various sound servers available. Consequently, this variety has resulted in a desire for a standard API to unify efforts.

In 2017, PipeWire began incorporating audio support, and would then go on to realize that unification for the most part.

==List of sound servers== * aRts * Enlightened Sound Daemon * JACK * Network Audio System * PipeWire * PulseAudio * sndio - OpenBSD audio and MIDI framework

=== Streaming === * Icecast * SHOUTcast

==References== <references />

==External links==

* [http://www.osnews.com/story.php?news_id=6720&page=2 Introduction to Linux Audio] * [http://mail.gnome.org/archives/gnome-multimedia/2001-May/msg00002.html RFC: GNOME 2.0 Multimedia strategy]

Category:Servers (computing)