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OBS stream screen in camera

Sometimes streaming the screen in an application sucks and is very limited. We can feed a stream to a virtual camera (V4L2 loopback device) in order to have more control in streams.

Note: This guide is for Linux. In windows, you can use the virtual camera feature. It comes builtin since version 26.0.0, but can also be added with the plugin obs-virtual-cam.

Kernel module

To create one of these devices (in Linux), we have to install and load a kernel module: v4l2loopback.

Instructions:

  • git clone https://github.com/umlaeute/v4l2loopback.git
  • cd v4l2loopback
  • make && sudo make install
  • sudo depmod -a
  • sudo modprobe v4l2loopback

By this point, you should have a new /dev/videoN device, where N is an integer. This device will probably be the last one of the ones you have.

This kernel module can be unloaded by doing sudo rmmod v4l2loopback. You might have to load it each time you turn on your pc and want to use it: sudo modprobe v4l2loopback.

The loading command can take some arguments to specify the number of devices created and the device ID’s of these devices, e.g.:

  • modprobe v4l2loopback devices=4
  • modprobe v4l2loopback video_nr=3,4,7 NOTE: the exclusive_caps=1 option can be useful to use the device in application that refuse to open devices that have capabilities besides CAPTURE, e.g.: Chrome/WebRTC.

OBS plugin

The obs-v4l2sink plugin provides the capability to OBS studio to output to V4L2 devices.

Instructions (depends on qtbase5-dev and libobs-dev):

  • git clone --recursive https://github.com/obsproject/obs-studio.git
  • git clone https://github.com/CatxFish/obs-v4l2sink.git
  • cd obs-v4l2sink
  • mkdir build && cd build
  • cmake -DLIBOBS_INCLUDE_DIR="../../obs-studio/libobs" -DCMAKE_INSTALL_PREFIX=/usr ..
  • make -j4
  • sudo make install

Note: We cloned obs-studios’s source code in order to links with its libraries during compilation.

Now, we can go to OBS and open the menu entry Tools > V4L2 Video Output. This will open a menu where we can select the video format and the path to the video device (/dev/videoN). After that, we just have to press start and our current OBS scene will be streamed on that device.