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SND_UAUDIO(4)		    Kernel Interfaces Manual		 SND_UAUDIO(4)

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 num-
       ber 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 par-
       enting 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.

FreeBSD	13.2		       November	12, 2016		 SND_UAUDIO(4)
NAME | SYNOPSIS | DESCRIPTION | SEE ALSO | HISTORY | AUTHORS | BUGS

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