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 device(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/ossxmix). 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

                                                11 February 2015                                      vmixctl(8)