ALSA 0.9.x Developer documentation

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[edit] Background Info

The Advanced Linux Sound Architecture comes with a driver API & library API. Our aim is to describe hardware as close as possible in drivers, but in userspace, the alsa-lib covers the hardware differences (if required). It's possible for applications to control all hardware features (if required).


Q: Why is ALSA more advanced than OSS?

  • kernel-space supports only h/w-level capabilities
  • multi-thread safe design
  • transparent use of plugin architecture to handle format,rate,channel cnt and many other conversions
  • support for non-interleaved interfaces
  • user-space software mixing (dmix)
  • user-space "loopback/snoop" capabilities
  • merging multiple cards into a single virtual device
  • hiding non-ALSA-drivers behind a consistent user-space API (e.g. IEEE1394 drivers, or JACK)
  • consistent and generic control API for managing h/w controls
  • sufficiently flexible mixer architecture to handle modern audio interfaces fully (rather than reducing them to a simplistic device)
  • consistent support for multiple instances of the same card
  • linked operations of multiple cards
  • and more...

Currently we need developers to write docs on the ctl API. Until then you will have to read the code and reference other applications for more advanced info.

[edit] Older documents

The ALSA HOWTO/FAQ documentation tries to do the ALSA driver installation easier. If you have any ideas or questions regarding this documentation, please, leave a message on the alsa-devel at lists.sourceforge.net mailing list.

The ALSA-sound-mini-HOWTO describes the installation of the ALSA sound drivers for Linux. This HOWTO is also available from the Linux Documentation Project, take a look at http://metalab.unc.edu/LDP/mirrors.html to find your nearest mirror. You can get this HOWTO in various formats:

There is also an old ALSA FAQ document from John Fulmer.

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