1.\" $NetBSD: uaudio.4,v 1.15 2002/02/12 19:53:57 jdolecek 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 November 12, 2016 31.Dt SND_UAUDIO 4 32.Os 33.Sh NAME 34.Nm snd_uaudio 35.Nd USB audio and MIDI device driver 36.Sh SYNOPSIS 37To compile this driver into the kernel, place the following lines in your 38kernel configuration file: 39.Bd -ragged -offset indent 40.Cd "device sound" 41.Cd "device usb" 42.Cd "device snd_uaudio" 43.Ed 44.Pp 45Alternatively, to load the driver as a module at boot time, place the 46following line in 47.Xr loader.conf 5 : 48.Bd -literal -offset indent 49snd_uaudio_load="YES" 50.Ed 51.Sh DESCRIPTION 52The 53.Nm 54driver provides support for 55.Tn USB 56audio class devices and 57.Tn USB 58MIDI class devices. 59.Pp 60A 61.Tn USB 62audio device consists of a number of components: 63input terminals (e.g.\& USB digital input), output terminals (e.g.\& 64speakers), and a number of units in between (e.g.\& volume control). 65.Pp 66Refer to the 67.Ql USB Audio Class Specification 68for more information. 69.Sh SEE ALSO 70.Xr sound 4 , 71.Xr usb 4 72.Rs 73.%T "USB Audio Class Specifications" 74.%U http://www.usb.org/developers/docs/devclass_docs/ 75.Re 76.Sh HISTORY 77The 78.Nm 79driver first appeared in 80.Fx 4.7 . 81.Sh AUTHORS 82This manual page was adopted from 83.Nx 1.6 84and modified for 85.Fx 86by 87.An Hiten Pandya Aq Mt hmp@FreeBSD.org . 88.Sh BUGS 89The 90.Tn PCM 91framework in 92.Fx 93only supports synchronous device detach. 94That means all mixer and DSP character devices belonging to a given 95USB audio device must be closed when receiving an error on a DSP read, 96a DSP write or a DSP IOCTL request. 97Else the USB audio driver will wait for this to happen, preventing 98enumeration of new devices on the parenting USB controller. 99.Pp 100Some USB audio devices might refuse to work properly unless the sample 101rate is configured the same for both recording and playback, even if 102only simplex is used. 103See the 104.Va dev.pcm.%d.[play|rec].vchanrate 105sysctls. 106.Pp 107The 108.Tn PCM 109framework in 110.Fx 111currently doesn't support the full set of USB audio mixer 112controls. 113Some mixer controls are only available as 114.Va dev.pcm.%d.mixer 115sysctls. 116