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Mac 101: Audio Attachments
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oss_usb(7) OSS Devices oss_usb(7) NAME
oss_usb - USB Audio/MIDI/Mixer driver DESCRIPTION
The Open Sound System driver for USB Audio and MIDI devices. AUDIO The Audio driver supports: o 8-96Khz Playback/Recording o 8 or 16 or 32 bits o 2, 4, 6 or 8 channel audio. o SPDIF digital output and Input o AC3 passthrough o Volume control and device input mixer MIDI 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 models). USB MIXER 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) ALTERNATIVE SETTINGS 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 oss- mix(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 ossinfo(1) command (ossinfo -a -v3) to find out the devices supported by the currently selected alternative settings and the capabilities of them. KNOWN BUGS
Under Linux it is necessary to run the ossdetect -d and ossdevlinks commands after an USB device has been hot-plugged. Alternatively you can execute soundoff and soundon to reload OSS. OPTIONS
None FILES
/etc/oss4/conf/oss_usb.conf Device configuration file AUTHOR
4Front Technologies 16 December 2012 oss_usb(7)
