7(16 December 2012) 7(16 December 2012)
NAME
sndstat - Open Sound System status device
DESCRIPTION
/dev/sndstat is a text formatted device special file that returns information about available (OSS) sound devices. This device file is
obsolete and the ossinfo(1) utility should be used instead.
Notice that the device numbering used in this file is different that the official numbering used by ossinfo(1) and some other utilities.
/dev/sndstat uses device numbers that match the "legacy" /dev/dspN, /dev/midiN and /dev/mixerN device files.
Application programs should not use /dev/sndstat to obtain information about the sound devices. The format of this file may change in the
future and /dev/sndstat may even be removed from OSS in distant future. OSS 4.0 and later has an ioctl interface for getting detailed and
reliable information about the devices.
AUDIO USAGE HISTORY
/dev/sndstat reports some history information about previously run audio applications. This section is a debugging aid for application
developers and it will be moved to the ossinfo program in the future.
For example:
History:
/dev/oss/hdaudio0/pcm0.10: pid 6326 cmd 'error_test' OUT Play events:01009:2 Rec events:01002:0
/dev/oss/hdaudio0/pcm0.10: pid 6329 cmd 'mpg123' OUT
/dev/oss/hdaudio0/pcm0.10: pid 6329 cmd 'mpg123' OUT
/dev/oss/hdaudio0/pcm0.10: pid 6329 cmd 'mpg123' OUT
Each line will show the the device name, PID and name of the application (if known) and access mode (IN and/or OUT). There may also be
additional info about buffer underruns/overruns and other recording and playback related events.
Each Play and rec events consist of 5-6 digit event code and a parameter separated by a colon. A list of defined event codes and their
explanations can be found from http://manuals.opensound.com/developer/oss_error_codes.html. Purpose of these events is to inform applica-
tion developers by potential problems in their code.
COMPATIBILITY
/dev/sndstat has been available in all OSS versions. However in OSS 4.0 and later this device file should only be used by applications
written for earlier OSS versions.
OPTIONS
None
PROGRAMMING INFORMATION
Some applications use /dev/sndstat to find the audio devices available in the system. This method is no longer recommended. Applications
should use the SNDCTL_AUDIOINFO(2) ioctl call to find the devices.
SEE ALSO
o dsp(7) - Audio device files
o mixer(7) - Mixer (control panel) device files
o midi(7) - MIDI device files
FILES
/dev/sndstat
AUTHOR
4Front Technologies
OSS Devices 7(16 December 2012)
Check Out this Related Man Page
vmixctl(8) OSS System Administration Commands vmixctl(8)NAME
vmixctl - Open Sound System utility to control the vmix subsystem.
SYNOPSIS
o vmixctl attach [attach_options...] audiodev [inputdev]
o vmixctl detach [attach_options...] audiodev
o vmixctl rate audiodev samplerate
o vmixctl remap audiodev channels
DESCRIPTION
The vmixctl program can be used to attach or detach the virtual mixer subsystem (vmix) to/from audio devices. In addition it can be used to
control vmix related parameters such as the sampling rate to be used with the device.
By default most OSS drivers will attach virtual mixer to the primary audio device of the sound card (or motherboard audio chip) when the
device is attached. However possible secondary audio devices (engines) will not have vmix attached by default. In additional professional
audio devices will be attached without vmix because mixing may cause some unwanted distortion to the signal.
ATTACHING VMIX TO AN AUDIO DEVICE
There are two forms of vmixctl attach command:
o vmixctl attach audiodev This alternative is to be used with devices that support only output or have a single audio device file that
supports full duplex.
o vmixctl attach audiodev inputdev The second form is to be used with devices that have separate output and input device files. The
"audiodev" parameter defines the output device and the "inputdev" parameter is the device file to be used for input direction. Note
that both device files must belong to the same "physical" sound card. In some cases it might be possible to use one sound card for
playback and another for recording. However this configuration is not supported and the result may not be functional.
To find out the right device file names (audiodev and inputdev) you can use the "ossinfo -a" command.
ATTACH OPTIONS
o -r Disable recording functionality. By default vmix will support recording if the master device(s) support it.
o -p Do not preallocate client engines. By default vmix will preallocate first 4 (out of 8) client engines when attaching to the
device. The remaining engines will be allocated on-demand if there are more concurrent applications that use the device.
o -M Make vmix use more fragments.
o -V Make client devices visible (have private device nodes under /dev).
o -c <n> Preallocate <n> client engines instead of 4. However -p option makes this option ineffective.
EXAMPLES
o vmixctl attach /dev/oss/oss_envy240/pcm0
o vmixctl attach /dev/oss/oss_envy240/pcm0 /dev/oss/oss_envy240/pcmin0
SETTING THE SAMPLING RATE USED BY VMIX
The virtual mixer subsystem will set the physical audio devce(s) to use fixed sampling rate that is 48000 Hz by default. It is possible to
use "vmixctl rate audiodev" to switch vmix to use some different rate with this device (pair). You should use "ossinfo -a -v2" to verify
that the sampling rate is actually supported by the device. Otherwise the actual device may enforce vmix to use the nearest supported rate
(or some default rate).
The "audiodev" parameter is the device file name (see ossinfo -a) that is used for playback. The input device name doesn't need to be spec-
ified.
Note that some professional audio devices may be locked to external sampling rate or some fixed rate (defined in ossmix/ossxmis). In such
case the rate is not changeable by vmixctl.
EXAMPLE
o vmixctl rate /dev/oss/oss_envy240/pcm0 44100
CHANGING THE VMIX CHANNEL MAP
The vmix subsystem can remap channels, so that all output sent to a channel via vmix will end up being played on a different channel. The
syntax uses a list of channels, where typically 0=default, 1=left, 2=right, 3=center, 4=lfe, 5=left surround, 6=right surround, 7=left rear
and 8=right rear. Note that vmix-channels should be set first to Multich if vmix is to recognize the extra channels.
EXAMPLES
o vmixctl remap /dev/dsp 2 1 #switch left and right
o vmixctl remap /dev/dsp 0 0 0 0 6 5 #switch left and right surround
DETACHING VMIX FROM AN AUDIO DEVICE
It is possible to detach vmix from an audio device if it causes problems with applications by using "vmix detach audiodev".
It is not possible to detach and (re)attach vmix to the same device more than few times. Use the vmix-enable setting in the control panel
(ossxmix or ossmix) to disable/re-enable vmix if you need to do it repeatedly. Use vmix detach only if you need to attach virtual mixer
using different parameters.
EXAMPLE
o vmix detach /dev/oss/oss_envy240/pcm0
POSSIBLE BUGS
o The control panel elements related with vmix are not removed from the mixer API when vmix is detached. This may be somehow confus-
ing.
SEE ALSO soundoff(1), soundon(1), ossmix(1), ossxmix(1)FILES
/usr/sbin/vmixct
AUTHOR
4Front Technologies
16 December 2012 vmixctl(8)