- USB Audio/MIDI/Mixer driver
The Open Sound System driver for USB Audio and MIDI devices.
The Audio driver supports:
- 8-96Khz Playback/Recording
- 8 or 16 or 32 bits
- 2, 4, 6 or 8 channel audio.
- SPDIF digital output and Input
- AC3 passthrough
- Volume control and device input mixer
The oss_usb driver supports all MIDI devices that are compatible with the
official USB MIDI specification. In addition the driver supports few devices
that use their own private protocol (including some Yamaha and Midiman
The USB Audio mixer is a new type of mixer that doesn't have the normal volume
controls found on AC97 or Legacy SB devices. The USB audio mixer provides
control for selecting the Alternate device setting - this usually allows the
device to be switched into a Professional audio mode (eg 24bit or 96Khz mode)
Some USB audio devices use a feature called as alternative settings for
bandwidth management. Typically such devices have multiple high speed inputs
and outputs that may require more bandwidth than provided by the USB bus. The
alternative settings feature is used to select between multiple low speed
devices or just few high speed devices.
When the device has multiple alternative settings an "altsetting"
selector will be visible in the control panel for the device (use
(1) or ossxmix
(1) to change it). Alternative setting OFF
means that all audio devices are disabled. The other settings provide
different combinations of high/medium speed devices. You can use the
(1) command (ossinfo -a -v3
) to find out the
devices supported by the currently selected alternative settings and the
capabilities of them.
Under Linux it is necessary to run the ossdetect -d
commands after an USB device has been hot-plugged. Alternatively you can
execute soundoff and soundon to reload OSS.
/etc/oss4/conf/oss_usb.conf Device configuration file