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UAUDIO(4)                  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 outputs.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 chorus 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.

NetBSD 7.1.2                  September 20, 2011                  NetBSD 7.1.2