UAUDIO(4) NetBSD Kernel Interfaces Manual UAUDIO(4)
uaudio -- USB audio device driver
uaudio* at uhub? audio* at audiobus?
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 indi- cates 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, out- puts.speaker.treble, outputs.speaker.mute, out- puts.speaker, or likewise. processing A processing unit does one of a number of audio process- ing functions (e.g., channel up-down mixing, Dolby Pro- Logic, or chorus effects). The name of the on-off con- trol is proN.M-enable, where N is a number that identi- fies 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 pro- cessing 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.
audio(4), usb(4) USB Approved Class Specification Documents, http://www.usb.org/developers/docs/devclass_docs/.
The uaudio driver appeared in NetBSD 1.5.
Releases 1.0 and 2.0 of the USB Audio class specification are not mutu- ally compatible. The uaudio driver only supports devices compliant with Release 1.0. There is no support for multiple-endpoints audio stream, adaptive record- ing, async playback, and TYPE-II/III formats. There is the possibility that a device has multiple mixer items which have the same name. NetBSD 9.0 January 26, 2015 NetBSD 9.0
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