Home | History | Annotate | Line # | Download | only in man4 
 $NetBSD: uaudio.4,v 1.31 2024/05/22 00:25:56 uwe Exp $

 Copyright (c) 1999-2024 The NetBSD Foundation, Inc.
 All rights reserved.

 This code is derived from software contributed to The NetBSD Foundation
 by Lennart Augustsson.

 Redistribution and use in source and binary forms, with or without
 modification, are permitted provided that the following conditions
 are met:
 1. Redistributions of source code must retain the above copyright
 notice, this list of conditions and the following disclaimer.
 2. Redistributions in binary form must reproduce the above copyright
 notice, this list of conditions and the following disclaimer in the
 documentation and/or other materials provided with the distribution.

 THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 POSSIBILITY OF SUCH DAMAGE.

.Dd May 21, 2024
.Dt UAUDIO 4
.Os
.Sh NAME
.Nm uaudio
.Nd USB audio device driver
.Sh SYNOPSIS
.Cd "uaudio* at uhub?"
.Cd "audio* at audiobus?"
.Sh DESCRIPTION
The
.Nm
driver provides support for
.Tn USB
audio class devices.

p
A
.Tn USB
audio device consists of a number of components:
input terminals

q e.g. USB digital input ,
output terminals

q e.g. speakers ,
and a number of units in between

q e.g. volume control .
The following types of units are handled by the
.Nm
driver and are accessible via the mixer

q see Xr audio 4
interface:
l -tag -width Em t Em 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
.Sm off
.Li mix Ar N Li \|- Ar S ,
.Sm on
where
.Ar N
is a number that identifies which mixer it is and
.Ar S
which input.
.
t Em selector A selector unit selects one of multiple audio sources such as mic-in
and line-in.
The name of the control is
.Sm off
.Li sel Ar N Li \|- Ar S1S2S3... ,
.Sm on
where
.Ar N
is a number that identifies which selector unit it is and the sequence of
.Ar Sn
indicates candidate units for the audio source.
.
t Em 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
.Li outputs.speaker.bass ,
.Li outputs.speaker.treble ,
.Li outputs.speaker.mute ,
.Li outputs.speaker ,
or likewise.
.
t Em processing A processing unit does one of a number of audio processing functions

q e.g., channel up-down mixing, Dolby ProLogic, or chorus effects .
The name of the on\[en]off control is
.Sm off
.Li pro Ar N Li . Ar M Li \|-enable ,
.Sm on
where
.Ar N
is a number that identifies which processing unit it is and
.Ar M
which kind.
Depending on the type of processing unit there may be other controls
as well.
.
t Em extension An extension unit performs some unspecified audio processing
The name of the on\[en]off control is
.Sm off
.Li ext Ar N Li \|-enable ,
.Sm on
where
.Ar N
is a number that identifies which processing unit it is.
.El

p
For more information the
.Tn USB
Audio class specification is indispensable
reading.
.Sh SEE ALSO
.Xr audio 4 ,
.Xr usb 4
.Rs
.%T "USB Approved Class Specification Documents"
.%U http://www.usb.org/developers/docs/devclass_docs/
.Re
.Sh HISTORY
The
.Nm
driver
appeared in
.Nx 1.5 .
Support for USB Audio Class 2.0 devices appeared in
.Nx 11.0 .
.Sh BUGS
There is no support for multiple-endpoints audio stream,
adaptive recording, async playback, and TYPE-II/III formats.

p
There is the possibility that a device has multiple mixer items
which have the same name.