1.\" $NetBSD: uaudio.4,v 1.25 2011/09/20 19:31:47 wiz Exp $ 2.\" 3.\" Copyright (c) 1999 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Lennart Augustsson. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 18.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 19.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 20.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 21.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 22.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28.\" POSSIBILITY OF SUCH DAMAGE. 29.\" 30.Dd September 20, 2011 31.Dt UAUDIO 4 32.Os 33.Sh NAME 34.Nm uaudio 35.Nd USB audio device driver 36.Sh SYNOPSIS 37.Cd "uaudio* at uhub?" 38.Cd "audio* at audiobus?" 39.Sh DESCRIPTION 40The 41.Nm 42driver provides support for 43.Tn USB 44audio class devices. 45.Pp 46A 47.Tn USB 48audio device consists of a number of components: 49input terminals (e.g. USB digital input), output terminals (e.g. 50speakers), and a number of units in between (e.g. volume control). 51The following types of units are handled by the 52.Nm 53driver and are accessible via the mixer (see 54.Xr audio 4 ) 55interface: 56.Bl -tag -width Dv -offset 3n -compact 57.It mixer 58A mixer has a number of inputs and one output. 59Each input has a control that determines its volume in the output. 60The name of the control is 61.Ar mixN-S , 62where 63.Ar N 64is a number that identifies which mixer it is and 65.Ar S 66which input. 67.It selector 68A selector unit selects one of multiple audio sources such as mic-in 69and line-in. 70The name of the control is 71.Ar selN-S1S2S3... , 72where 73.Ar N 74is a number that identifies which selector unit it is and the sequence of 75.Ar Sn 76indicates candidate units for the audio source. 77.It feature 78A feature unit changes the sound in some way, like bass, treble, 79mute, or volume. 80The name of the control is determined in a heuristic way. 81If the unit changes the sound to a speaker output terminal, 82the names of the controls may be outputs.speaker.bass, outputs.speaker.treble, 83outputs.speaker.mute, outputs.speaker, or likewise. 84.It processing 85A processing unit does one of a number of audio processing functions 86(e.g., channel up-down mixing, Dolby ProLogic, or chorus effects). 87The name of the on-off control is 88.Ar proN.M-enable , 89where 90.Ar N 91is a number that identifies which processing unit it is and 92.Ar M 93which kind. 94Depending on the type of processing unit there may be other controls 95as well. 96.It extension 97An extension unit performs some unspecified audio processing 98The name of the on-off control is 99.Ar extN-enable , 100where 101.Ar N 102is a number that identifies which processing unit it is. 103.El 104.Pp 105For more information the 106.Tn USB 107Audio class specification is indispensable 108reading. 109.Sh SEE ALSO 110.Xr audio 4 , 111.Xr usb 4 112.Rs 113.%T "USB Approved Class Specification Documents" 114.%U http://www.usb.org/developers/devclass_docs/ 115.Re 116.Sh HISTORY 117The 118.Nm 119driver 120appeared in 121.Nx 1.5 . 122.Sh BUGS 123There is no support for multiple-endpoints audio stream, 124adaptive recording, async playback, and TYPE-II/III formats. 125.Pp 126There is the possibility that a device has multiple mixer items 127which have the same name. 128