UAUDIO(4) BSD Kernel Interfaces Manual UAUDIO(4)
NAME
uaudio -- USB audio device driver
SYNOPSIS
uaudio* at uhub?
audio* at audiobus?
DESCRIPTION
The uaudio driver provides support for USB audio class devices.
A USB audio device consists of a number of components: input terminals (e.g. USB digital input), output terminals (e.g. speakers), and a
number of units in between (e.g. volume control). The following types of units are handled by the uaudio driver and are accessible via the
mixer (see audio(4)) interface:
mixer A mixer has a number of inputs and one output. Each input has a control that determines its volume in the output. The name
of the control is mixN-S, where N is a number that identifies which mixer it is and S which input.
selector A selector unit selects one of multiple audio sources such as mic-in and line-in. The name of the control is
selN-S1S2S3..., where N is a number that identifies which selector unit it is and the sequence of Sn indicates candidate
units for the audio source.
feature A feature unit changes the sound in some way, like bass, treble, mute, or volume. The name of the control is determined in
a heuristic way. If the unit changes the sound to a speaker output terminal, the names of the controls may be out-
puts.speaker.bass, outputs.speaker.treble, outputs.speaker.mute, outputs.speaker, or likewise.
processing A processing unit does one of a number of audio processing functions (e.g., channel up-down mixing, Dolby ProLogic, or cho-
rus effects). The name of the on-off control is proN.M-enable, where N is a number that identifies which processing unit it
is and M which kind. Depending on the type of processing unit there may be other controls as well.
extension An extension unit performs some unspecified audio processing The name of the on-off control is extN-enable, where N is a
number that identifies which processing unit it is.
For more information the USB Audio class specification is indispensable reading.
SEE ALSO
audio(4), usb(4)
USB Approved Class Specification Documents, http://www.usb.org/developers/devclass_docs/.
HISTORY
The uaudio driver appeared in NetBSD 1.5.
BUGS
There is no support for multiple-endpoints audio stream, adaptive recording, async playback, and TYPE-II/III formats.
There is the possibility that a device has multiple mixer items which have the same name.
BSD
September 20, 2011 BSD