obs-backscrub

Integration for backscrub project into OBS Studio

What is this?

It's a video filter plugin for OBS Studio (currently limited to video capture devices that produce YUY2 format streams), which uses the backscrub library to remove the background of a video source (replacing it with green), allowing subsequent chroma keying of alternate backgrounds.

Neat! How do I build it?

Linux

• Install the dependencies (assuming you have OBS Studio already!): build-essentials, libobs-dev, libopencv-dev
• Clone this project.
• Do the CMake dance:

  % mkdir build; cmake -B build; cmake --build build -j

This will pull the submodules (backscrub and Tensorflow), configure them (mostly Tensorflow fetching several more dependencies) then compile everything. Expect to wait 10+ minutes for a full build, and lose ~2GB of disk space.

Windows

NB: This is fiddly, fragile and poorly tested

• Development environment: VS2019 community edition, on Server2019 / Windows10/11
• Download and install dependencies (assuming you have OBS Studio already!):
  • OpenCV 3.4.14: https://sourceforge.net/projects/opencvlibrary/files/3.4.14/opencv-3.4.14-vc14_vc15.exe/download
  • Note installed path, eg: C:\Users\phlash\Download\opencv
• Download OBS source code and bodge an import library (in lieu of a libobs-dev package):
  • Match your version, eg for 29.0.2: https://github.com/obsproject/obs-studio/archive/refs/tags/29.0.2.zip
  • Create a fresh libobs folder eg: C:\Users\phlash\Downloads\libobs
  • Save LibObsConfig.zip to the libobs folder and unpack in place to get a CMake config script
  • From OBS source ZIP, unpack only the libobs folder into folder above, then rename as inc, eg: C:\Users\phlash\Downloads\libobs\inc
  • Create a bin folder next to inc eg: C:\Users\phlash\Downloads\libobs\bin
  • Copy the OBS.DLL library out of your installed OBS Studio eg: C:\Program Files\obs-studio\bin\64bit\OBS.DLL into bin folder.
  • In a VS2019 Developer Command Prompt, generate an import library from the DLL, instructions modified from: https://stackoverflow.com/questions/9946322/how-to-generate-an-import-library-lib-file-from-a-dll

    C> cd <libobs\bin folder>
    C> echo LIBRARY OBS > obs.def
    C> echo EXPORTS >> obs.def
    C> for /f "skip=19 tokens=4" %A in ('dumpbin /exports OBS.DLL') do echo %A >> obs.def
    C> lib /def:obs.def /out:OBS.LIB /machine:x64

  • Clone this project.
  • Checkout windows-build branch.
  • In a VS2019 Developer Command Prompt Do the CMake dance, informing it where OpenCV and libobs are:

  C> mkdir build
  C> cmake -B build -D CMAKE_PREFIX_PATH="<OpenCV path>\build;<libobs folder>"
  C> cmake --build build -j

  • The build will fail, you need to fix up a bug in Tensorflow (tensorflow/tensorflow#54323)
    • Edit: tensorflow\tensorflow\core\lib\random\random_distributions_utils.h and replace M_PI symbol with 3.1415928.
  • Re-run build:

  C> cmake --build build -j

It's built - how do I install it?

Linux

I choose to create sym-links for the built object and the data directory out of the obs-studio installation, this avoids install-to-test issues:

% cd /lib/x86_64-linux-gnu/obs-plugins
% sudo ln -s /home/phlash/obs-backscrub/build/obs-backscrub.so .
% cd /usr/share/obs/obs-plugins
% sudo ln -s /home/phlash/obs-backscrub/data obs-backscrub

Windows

Not quite the same as Linux as Windows cannot do file symlinks, only folders, so we copy the built object and dependencies:

C> cd \Program Files\obs-studio\obs-plugin\64bit
C> copy \Users\phlash\obs-backscrub\build\obs-backscrub.dll
C> copy <OpenCV path>\build\x64\opencv-world3414d.dll
C> cd ..\..\data\obs-plugin
C> mklink /D obs-backscrub \Users\phlash\obs-backscrub\data

Using it?

Fire up OBS Studio - check the logs to ensure obs-backscrub.dll loads successfully.

Add a video capture source, go to filters, and add an audio/video filter 'Background scrubber'. That's it.