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 specified.

       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 confusing.

SEE ALSO

       soundoff(1), soundon(1), ossmix(1), ossxmix(1)

FILES

       /usr/sbin/vmixct

AUTHOR

       4Front Technologies

                                                 23 January 2023                                      vmixctl(8)