uaudio(4)
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UAUDIO(4) NetBSD 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 iden-
tifies 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 candi-
date units for the audio source.
feature A feature unit changes the sound in some way, like bass, tre-
ble, 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
outputs.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
chorus effects). The name of the on-off control is
proN.M-enable, where N is a number that identifies which pro-
cessing 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/docs/devclass_docs/.
HISTORY
The uaudio driver appeared in NetBSD 1.5. Support for USB Audio Class
2.0 devices appeared in NetBSD 11.0.
BUGS
There is no support for multiple-endpoints audio stream, adaptive record-
ing, async playback, and TYPE-II/III formats.
There is the possibility that a device has multiple mixer items which
have the same name.
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