Release notes for the USB audio and MIDI driver
===============================================
Important! This is a BETA test driver which means that it works wery
well with some of the devices but may fail completely with
some others. Also there may be problems with some applications
while most others work OK.
**************************************************************************
* At this moment the USB driver is ONLY AVAILABLE FOR Linux 2.6.8.1 and *
* later kernels. It will not be made vailable for older Linux kernels. *
* *
* Support for the other operating systems may be released in the future *
* but at this moment there are no specific plans. *
**************************************************************************
In the initial release the following USB audio devices are known to work:
M Audio Sonica Theater USB
M Audio USB AudioSport Duo
M Audio USB AudioSport Quatro
M Audio OmniStudio USB
Creative Sound Blaster Extigy
Creative Sound Blaster MP3+ USB
Logitec Quickcam Pro 4000 (mic)
Logitec USB Headset 20
Philips ToUcam Pro (mic)
Labtec LCS1040 Speaker System
Hercules Gamesurround MUSE Pocket
In addition most if not all other USB audio devices should work
but we have not been able to verify them.
The following USB MIDI devices are known to work.
M Audio USB MIDISPORT 2x2
Using USB sound devices with OSS
--------------------------------
To get USB audio working with OSS you should have the audio device plugged in
the system when installing OSS. Then run oss-install and select the
"Autodetect soundcards" function when getting to the configuration
screen (3rd screen). After autodetect you should have the USB device visible
in the device list. Save the configuration and start OSS using the soundon
command.
Alternative settings
--------------------
USB audio devices use so called "alternative settings" method to control
the USB bandwidth usage of the device. It's not possible to have multiple
hight speed devices in the system at the same time. For this reason the
devices usually have multiple alternative settings (numbered from 0 to N).
In some settings it possible to use all the devices but limited to 48 kHz
and 16 bits. Some other alternative settings permit higher rates such at
96 kHz and 24 bits but at the same time some of the inputs and outputs
may be switched off.
The alternative setting can be changed by starting the ossxmix applet and
by changing the altsetting parameter. Setting it to 0 disables all the
devices. Alternative setting 1 is the default.
To find out the right mixer device to use you can use the "ossinfo -x" command
to list the mixers. The start ossxmis with the -dN argument where N is the
mixer device number.
To see what the alternative settings do you need to switch the mode and to
execute the following command to list the audio devices and their current
feature set (in the initial USB driver version you will also need to play
or record some audio before the mode change takes effect).:
ossinfo -a -p -v3
The above comand shows if the device is available or not. It also shows the
sample rates and sample formats that are available.
The alternative settings mechanism doesn't affect any MIDI devices.
Possible problems
-----------------
In some systems it may be necessary to reboot the system after installation
(oss-install). Otherwise the kernel USB audio drivers take control of the
device which prevents OSS from loading.
If the USB audio device is not detected by soundconf or it doesn't get
initialized during soundon the most likely reason is that the system
doesn't see the device. Use the "lsusb" command to find out if the device
was detected by the kernel.
If the audio device was not reported then make sure all cables are properly
connected. If this doesn't help then reboot the system while the USB device
is powered on.