*audio driver on linux

Reference Essential Linux device drives

1. Audio connection


cpu ===> audio codec ===> MIC or speaker

ex: audio codec : AC97. TI TPS65950
audio codec converts digitial audio to analog sound for playing through speakers
Then, audio codec has "mixer" functionality

2.Linuc sound subsystem
ALSA is the sound subsystem of choice in the 2.6 kernel

Device node : /dev/snd/*

/dev/snd/controlC0 is control node for volume gain
/dev/snd/pcmC0D0p is a playback device, p is playback
/dev/snd/pcmC0D0c is a recording device, c is capture

3. Accessing information via /proc/asound and /sys/class/sound

4. ALSA library : user space alsa library alsa-lib which provides the libasound.so
ALSA utility : alsa-utils, alsamixer, amixer, alsactl , aplay and areocrd

5. Audio driver is build out of three main function
* Playback
* Capture
* Mixer control functions