Advanced Linux Sound Architecture

Information about Advanced Linux Sound Architecture

ALSA
Author:Jaroslav Kysela
Initial release:1998
Latest release:1.0.15 / October 16, 2007
OS:Linux
Genre:Audio
License:GPL and LGPL
Website:www.alsa-project.org
Enlarge picture
A screenshot of alsamixer.
Advanced Linux Sound Architecture (known by the acronym ALSA) is a Linux kernel component intended to replace the original Open Sound System (OSS) for providing device drivers for sound cards. Some of the goals of the ALSA project at its inception were automatic configuration of sound-card hardware, and graceful handling of multiple sound devices in a system, goals which it has largely met. A couple of different frameworks, such as JACK, use ALSA to allow performing low-latency professional-grade audio editing and mixing.

Led by Jaroslav Kysela, the project started from a Linux device driver for the Gravis Ultrasound sound card in 1998, and was developed separately from the Linux kernel until it was introduced in the 2.5 development series in 2002 (2.5.4-2.5.5)[1]. In the 2.6 version it replaces OSS by default, although a backwards-compatibility layer exists.

ALSA features

ALSA was designed to use some features which were not, at the time of its conception, supported by OSS:
  • Hardware based MIDI synthesis.
  • Hardware mixing of multiple channels.
  • Full-duplex operation.
  • Multiprocessor-friendly, thread-safe device drivers.
To provide these features cleanly, ALSA has a bigger and more complex API than OSS, so it can be harder to develop applications that use ALSA as their sound technology. However, ALSA also provides an optional OSS emulation layer, so the simpler and more portable OSS API can be used.

Besides the sound device drivers, ALSA bundles a user space library for application developers who want to use driver features with a higher level API than direct interaction with the kernel drivers.

See also

References

External links

Software design is a process of problem-solving and planning for a software solution. After the purpose and specifications of software is determined, software developers will design or employ designers to develop a plan for a solution.
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Jaroslav Kysela (aka perex) is the creator of the ALSA project for sound drivers in the Linux operating system. He now works at Novell.

External Links

  • [https://internet.perex.cz/~perex/ Kysela's Home Page]

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A software release is the distribution, whether public or private, of an initial or new and upgraded version of a computer software product.
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Open Sound System (OSS) is a standard interface for making and capturing sound in Unix operating systems. It is based on standard Unix devices (i.e. POSIX read, write, ioctl, etc.).
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A device driver, or software driver is a computer program allowing higher-level computer programs to interact with a computer hardware device.

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Sound Card

A Sound Blaster Live! Value card, a typical present-day PCI sound card

Connects to:
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JACK Audio Connection Kit or JACK is a sound server or daemon that provides low latency connections between so-called jackified applications. It is created by Paul Davis and others and licensed under the GNU GPL.

JACK is free audio software.
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Jaroslav Kysela (aka perex) is the creator of the ALSA project for sound drivers in the Linux operating system. He now works at Novell.

External Links

  • [https://internet.perex.cz/~perex/ Kysela's Home Page]

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Gravis Ultrasound or GUS is a sound card for the IBM PC compatible system platform, made by Canada-based Advanced Gravis Computer Technology Ltd. It was very popular in the demo scene in the 1990s, due to its superior sound quality compared to similarly-priced soundcards of
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Open Sound System (OSS) is a standard interface for making and capturing sound in Unix operating systems. It is based on standard Unix devices (i.e. POSIX read, write, ioctl, etc.).
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MIDI (Musical Instrument Digital Interface; IPA: /ˈmɪdi/) is an industry-standard protocol that enables electronic musical instruments, computers and other equipment to communicate, control and synchronize with each other.
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Hardware mixing is a performance feature of computer audio hardware which enables soundcards to receive multiple audio streams and play them all at the same time. Hardware mixing improves performance by offloading audio mixing operations from the CPU and performing them at hardware
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kernel space and user space. Kernel space is strictly reserved for running the kernel, device drivers and kernel extensions. In most operating systems, kernel memory is never swapped out to disk.
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LADSPA is an acronym for Linux Audio Developers Simple Plugin API. It is a standard for handling filters and effects, licensed under the GNU LGPL. It was originally designed for Linux through consensus on the Linux Audio Developers Mailing List, but works on a variety of
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