This file describes the mapping of ALSA mixer element's properties to
sets of Controls of the Port line that abstracts the mixer element.

L/R channels (mono false)
common volume false
(playback) vol true (not joined)
common switch false
(pb) switch true (joined)
Example: Master
-->
boolean MUTE
float VOLUME (or MASTER_GAIN)
float BALANCE (or PAN)
-- alternative:
boolean MUTE
compound [
float VOLUME (left)
float VOLUME (right)	// can order be guaranteed?
]
-------------------------------------------------------
pb channels: L (mono true)
common vol false
pb vol true (joined)
common switch: false
playback switch: true (joined)
Example: Master Mono
-->
float VOLUME
boolean MUTE
------------------------------------------------------
pb channels: L/R (mono false)

Example: Tone