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

In a Unix-like operating system, a sound server mixes different data streams 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, ESD, JACK, PulseAudio) * Sound subsystem (described as kernel modules or drivers; e.g.

OSS OSS or Oss may refer to: Places * Oss, a city and municipality in the Netherlands * Osh Airport, IATA code OSS People with the name * Oss (surname), a surname Arts and entertainment * ''O.S.S.'' (film), a 1946 World War II spy film about ...

, 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.

List of sound servers

* aRts *

Enlightened Sound Daemon In computing, the Enlightened Sound Daemon (ESD or EsounD) was the sound server for Enlightenment and GNOME. Esound is a small sound daemon for both Linux and UNIX. ESD was created to provide a consistent and simple interface to the audio devi ...

* JACK *

Network Audio System Network, networking and networked may refer to: Science and technology * Network theory, the study of graphs as a representation of relations between discrete objects * Network science, an academic field that studies complex networks Mathematics ...

PipeWire PipeWire is a server for handling audio, video streams, and hardware on Linux. It was created by Wim Taymans at Red Hat. It handles multimedia routing and pipeline processing. History In 2015, Taymans started work on PipeWire. It was based ...

* PulseAudio *

sndio sndio is the software layer of the OpenBSD operating system that manages sound cards and MIDI ports. It provides an optional sound server and a documented application programming interface to access either the server or the audio and MIDI hard ...

OpenBSD OpenBSD is a security-focused, free and open-source, Unix-like operating system based on the Berkeley Software Distribution (BSD). Theo de Raadt created OpenBSD in 1995 by forking NetBSD 1.0. According to the website, the OpenBSD project em ...

audio and MIDI framework

Streaming

* Icecast * SHOUTcast

References

External links

Introduction to Linux Audio

Servers (computing)