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     snd_uaudio -- USB audio device driver


     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):



     The snd_uaudio driver provides support for USB audio 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.


     sound(4), usb(4)

     USB Audio Class Specifications,


     The snd_uaudio driver first appeared in FreeBSD 4.7.


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


     The PCM framework in FreeBSD, as of this writing, does not handle device
     un-registrations in a properly abstracted manner, i.e., a detach request
     is refused by the PCM framework if the device is in use.  For USB and
     supposedly other detach-able busses, it is necessary to allow the device
     un-registration to complete successfully, otherwise the driver leaves
     wild pointers to invalid data structures and thus leading to a panic.