---
name: "vmixctl"
section: "8"
platform: "linux"
package: "oss4-base"
version: "4.2-build2010-2"
release: "Debian 8 (Jessie)"
platforms: ["linux"]
url: "https://new.carta.tech/vmixctl"
---

# vmixctl(8)

Open Sound System utility to control the vmix subsystem.

## 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)](/ossmix/1.md), [ossxmix(1)](/ossxmix/1.md)**

## FILES

**/usr/sbin/vmixct**

## AUTHOR

**4Front Technologies**