The ALSA library API is the interface to the ALSA drivers. Developers need to use the functions in this API to achieve native ALSA support for their applications. The currently designed interfaces are as follows:
Information Interface (/proc/asound)
Control Interface (/dev/snd/controlCX)
Mixer Interface (/dev/snd/mixerCXDX)
PCM Interface (/dev/snd/pcmCXDX)
Raw MIDI Interface (/dev/snd/midiCXDX)
Sequencer Interface (/dev/snd/seq)
Timer Interface (/dev/snd/timer)
For more information, refer to https://www.alsa-project.org/alsa-doc/alsa-lib/.