129 lines
4.0 KiB
Groff
129 lines
4.0 KiB
Groff
.\" $NetBSD: uaudio.4,v 1.23 2008/04/30 13:10:54 martin 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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.Dd June 22, 2005
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.Dt UAUDIO 4
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.Os
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.Sh NAME
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.Nm uaudio
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.Nd USB audio device driver
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.Sh SYNOPSIS
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.Cd "uaudio* at uhub?"
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.Cd "audio* at audiobus?"
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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.
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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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The following types of units are handled by the
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.Nm
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driver and are accessible via the mixer (see
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.Xr audio 4 )
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interface:
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.Bl -tag -width Dv -offset 3n -compact
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.It mixer
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A mixer has a number of inputs and one output. Each input has a control
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that determines its volume in the output.
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The name of the control is
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.Ar mixN-S ,
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where
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.Ar N
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is a number that identifies which mixer it is and
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.Ar S
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which input.
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.It selector
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A selector unit selects one of multiple audio sources such as mic-in
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and line-in.
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The name of the control is
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.Ar selN-S1S2S3... ,
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where
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.Ar N
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is a number that identifies which selector unit it is and the sequence of
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.Ar Sn
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indicates candidate units for the audio source.
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.It feature
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A feature unit changes the sound in some way, like bass, treble,
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mute, or volume.
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The name of the control is determined in a heuristic way.
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If the unit changes the sound to a speaker output terminal,
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the names of the controls may be outputs.speaker.bass, outputs.speaker.treble,
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outputs.speaker.mute, outputs.speaker, or likewise.
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.It processing
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A processing unit does one of a number of audio processing functions
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(e.g., channel up-down mixing, Dolby ProLogic, or chorus effects).
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The name of the on-off control is
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.Ar proN.M-enable ,
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where
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.Ar N
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is a number that identifies which processing unit it is and
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.Ar M
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which kind.
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Depending on the type of processing unit there may be other controls
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as well.
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.It extension
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An extension unit performs some unspecified audio processing
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The name of the on-off control is
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.Ar extN-enable ,
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where
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.Ar N
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is a number that identifies which processing unit it is.
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.El
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.Pp
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For more information the
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.Tn USB
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Audio class specification is indispensable
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reading.
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.Sh SEE ALSO
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The
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.Tn USB
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specifications can be found at:
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.Dv http://www.usb.org/developers/docs.html
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.Pp
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.Xr audio 4 ,
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.Xr usb 4
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.Sh HISTORY
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The
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.Nm
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driver
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appeared in
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.Nx 1.5 .
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.Sh BUGS
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There is no support for multiple-endpoints audio stream,
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adaptive recording, async playback, and TYPE-II/III formats.
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.Pp
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There is the possibility that a device has multiple mixer items
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which have the same name.
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