Description:

The Advanced Linux Sound Architecture (ALSA) provides audio and MIDI
functionality to the Linux operating system. ALSA has the following
significant features:
1. Efficient support for all types of audio interfaces, from consumer
soundcards to professional multichannel audio interfaces.
2. Fully modularized sound drivers.
3. SMP and thread-safe design.
4. User space library (alsa-lib) to simplify application programming
and provide higher level functionality.
5. Support for the older OSS API, providing binary compatibility for
most OSS programs.

These are the C header files for the alsa modules system,
which define structures and constants that are needed when building
most standard programs that use alsa.