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NAME
       snd_uaudio — USB audio and MIDI device driver


SYNOPSIS
       To compile this driver into the kernel, place the following lines in your kernel configuration file:

             device sound
             device usb
             device snd_uaudio

       Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5):

             snd_uaudio_load="YES"


DESCRIPTION
       The snd_uaudio driver provides support for USB audio class devices and USB MIDI class devices.

       A  USB  audio device consists of a number of components: input terminals (e.g. USB digital input), output
       terminals (e.g. speakers), and a number of units in between (e.g. volume control).

       Refer to the ‘USB Audio Class Specification’ for more information.


SEE ALSO
       sound(4), usb(4)

       USB Audio Class Specifications, http://www.usb.org/developers/docs/devclass_docs/.


HISTORY
       The snd_uaudio driver first appeared in FreeBSD 4.7.


AUTHORS
       This manual page was adopted from NetBSD 1.6 and modified for FreeBSD by Hiten Pandya <hmp@FreeBSD.org>.


BUGS
       The PCM framework in FreeBSD only supports synchronous device detach.   That  means  all  mixer  and  DSP
       character  devices  belonging to a given USB audio device must be closed when receiving an error on a DSP
       read, a DSP write or a DSP IOCTL request.  Else the USB audio  driver  will  wait  for  this  to  happen,
       preventing enumeration of new devices on the parenting USB controller.

       Some  USB  audio  devices might refuse to work properly unless the sample rate is configured the same for
       both recording and playback, even if only  simplex  is  used.   See  the  dev.pcm.%d.[play|rec].vchanrate
       sysctls.

       The  PCM  framework  in FreeBSD currently doesn't support the full set of USB audio mixer controls.  Some
       mixer controls are only available as dev.pcm.%d.mixer sysctls.

Debian                                          November 12, 2016                                  SND_UAUDIO(4)