ALSA (Linux)
ALSA (an
acronym for
Advanced Linux Sound Architecture) is a
Linux kernel component intended to replace the original
Open Sound System (OSS) for providing 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 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.
ALSA was designed to 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 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.
*
LADSPA*
DSSI*
Official site* http://alsa.opensrc.org/ (a big ALSA
Wiki)
