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118 lines
3.5 KiB
Groff
118 lines
3.5 KiB
Groff
.\" $NetBSD: uaudio.4,v 1.15 2002/02/12 19:53:57 jdolecek Exp $
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.\"
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.\" Copyright (c) 1999 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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.\"
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.\" This code is derived from software contributed to The NetBSD Foundation
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.\" by Lennart Augustsson.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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.\" POSSIBILITY OF SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd November 12, 2016
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.Dt SND_UAUDIO 4
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.Os
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.Sh NAME
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.Nm snd_uaudio
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.Nd USB audio and MIDI device driver
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.Sh SYNOPSIS
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To compile this driver into the kernel, place the following lines in your
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kernel configuration file:
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.Bd -ragged -offset indent
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.Cd "device sound"
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.Cd "device usb"
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.Cd "device snd_uaudio"
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.Ed
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.Pp
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Alternatively, to load the driver as a module at boot time, place the
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following line in
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.Xr loader.conf 5 :
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.Bd -literal -offset indent
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snd_uaudio_load="YES"
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.Ed
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.Sh DESCRIPTION
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The
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.Nm
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driver provides support for
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.Tn USB
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audio class devices and
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.Tn USB
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MIDI class devices.
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.Pp
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A
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.Tn USB
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audio device consists of a number of components:
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input terminals (e.g.\& USB digital input), output terminals (e.g.\&
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speakers), and a number of units in between (e.g.\& volume control).
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.Pp
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Refer to the
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.Ql USB Audio Class Specification
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for more information.
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.Sh SEE ALSO
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.Xr sound 4 ,
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.Xr usb 4
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.Rs
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.%T "USB Audio Class Specifications"
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.%U http://www.usb.org/developers/docs/devclass_docs/
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.Re
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.Sh HISTORY
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The
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.Nm
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driver first appeared in
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.Fx 4.7 .
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.Sh AUTHORS
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This manual page was adopted from
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.Nx 1.6
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and modified for
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.Fx
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by
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.An Hiten Pandya Aq Mt hmp@FreeBSD.org .
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.Sh BUGS
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The
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.Tn PCM
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framework in
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.Fx
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only supports synchronous device detach.
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That means all mixer and DSP character devices belonging to a given
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USB audio device must be closed when receiving an error on a DSP read,
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a DSP write or a DSP IOCTL request.
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Else the USB audio driver will wait for this to happen, preventing
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enumeration of new devices on the parenting USB controller.
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.Pp
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Some USB audio devices might refuse to work properly unless the sample
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rate is configured the same for both recording and playback, even if
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only simplex is used.
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See the
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.Va dev.pcm.%d.[play|rec].vchanrate
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sysctls.
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.Pp
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The
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.Tn PCM
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framework in
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.Fx
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currently doesn't support the full set of USB audio mixer
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controls.
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Some mixer controls are only available as
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.Va dev.pcm.%d.mixer
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sysctls.
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