UAUDIO(4)						   BSD Kernel Interfaces Manual 						 UAUDIO(4)

NAME

     uaudio -- USB audio device driver

SYNOPSIS

     uaudio* at uhub?
     audio*  at audiobus?

DESCRIPTION

     The 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).	The following types of units are handled by the uaudio driver and are accessible via the
     mixer (see audio(4)) interface:
	mixer	      A mixer has a number of inputs and one output.  Each input has a control that determines its volume in the output.  The name
		      of the control is mixN-S, where N is a number that identifies which mixer it is and S which input.
	selector      A selector unit selects one of multiple audio sources such as mic-in and line-in.  The name of the control is
		      selN-S1S2S3..., where N is a number that identifies which selector unit it is and the sequence of Sn indicates candidate
		      units for the audio source.
	feature       A feature unit changes the sound in some way, like bass, treble, mute, or volume.  The name of the control is determined in
		      a heuristic way.	If the unit changes the sound to a speaker output terminal, the names of the controls may be out-
		      puts.speaker.bass, outputs.speaker.treble, outputs.speaker.mute, outputs.speaker, or likewise.
	processing    A processing unit does one of a number of audio processing functions (e.g., channel up-down mixing, Dolby ProLogic, or cho-
		      rus effects).  The name of the on-off control is proN.M-enable, where N is a number that identifies which processing unit it
		      is and M which kind.  Depending on the type of processing unit there may be other controls as well.
	extension     An extension unit performs some unspecified audio processing The name of the on-off control is extN-enable, where N is a
		      number that identifies which processing unit it is.

     For more information the USB Audio class specification is indispensable reading.

SEE ALSO

     audio(4), usb(4)

     USB Approved Class Specification Documents, http://www.usb.org/developers/devclass_docs/.

HISTORY

     The uaudio driver appeared in NetBSD 1.5.

BUGS

     There is no support for multiple-endpoints audio stream, adaptive recording, async playback, and TYPE-II/III formats.

     There is the possibility that a device has multiple mixer items which have the same name.

BSD
								September 20, 2011							       BSD