Editing Sound server

{{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 [[sound reproduction|audio]] devices (usually a [[sound card]]). It commonly runs as a [[background process]].

== Sound server in an operating system==
[[File:Soundserver eng.png|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:

* Applications (e.g. mp3 player, web video)
* Sound server (e.g. [[aRts]], [[Enlightened Sound Daemon|ESD]], [[JACK Audio Connection Kit|JACK]], [[PulseAudio]])
* Sound subsystem (described as kernel modules or drivers; e.g. [[Open Sound System|OSS]], [[Advanced Linux Sound Architecture|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 (computer software)|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.

==List of sound servers==
* [[aRts]]
* [[Enlightened Sound Daemon]]
* [[JACK Audio Connection Kit|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)]]