How to use OBS for presentation

In this small blogpost, I wrote a short tutorial on how I use OBS for academic presentations.

Last week I did a presentation of my recent work to my research group. I decided to go beyond the way of presenting by only talking in mic and came with this set up :

Trying out a new set up with OBS for a remote presentation tomorrow. Hopefully it will be a bit more interactive than just talking in a mic ! pic.twitter.com/GwiDredw6w
— Thomas Feuillen (@TFeuillen) November 1, 2020

Which is essentially a minimalist version of Steve Brunton’s set up

Very excited to share a new video diving into the mathematics of compressed sensing.

I'm always surprised that it's possible to reconstruct full images from a random subsampling of pixels.

More videos on this topic each Friday.

YouTube video: https://t.co/7a6bbE3woZ pic.twitter.com/byqoq9wdXm
— Steven Brunton (@eigensteve) October 9, 2020

This way of presenting allows you to interact with your slides and with the audience in a way that feels more pre-covid times.

Because my research wanted to know how to do it, I thought I would share this tutorial.

What you’ll need :

A computer
A webcam
A white or black wall
A presentation with white or black background
OBS
A remote presentation software (zoom/MS teams)
A external mic (optional)
A tripod for the webcam (optional)

Let’s go

After installing OBS let us configure the scene that we will use to present our work.

You will start with a scene that is all black:

The first thing that you can do is to add a background image in case something goes wrong at least the screen won’t go black.

Now that this is done, let’s add the webcam to the scene and resize it so that it fills the entire screen.

You might notice that the webcam does not mirror your movements when you move (eg, when you point physically to the upper left corner, the webcam feed points to the upper right), which makes it hard when presenting.

We can add a transform on the webcam feed such that it mirrors your movements :

Now that you can see yourself in front of a (kinda) white background, we can add the presentation. Because Linux is sometimes fiddly with OBS when it comes to window capture, I use my web browser as the PDF viewer. You can also resize the presentation window according to your needs (I like having a small space without the presentation so that I am not always in front of something) and use presentation mode in your pdf viewer to remove the edges.

The next step is to remove the white background of the presentation. To do that, we add a filter on the presentation:

The background has now disappeared !

If your wall is not white enough, or like me, there isn’t enough light, you can increase the brightness of the webcam:

Here is the (almost) final result !

The last few steps are setting up how to both change the slides of your presentation while seeing the feed, and how to output it to your presentation software.

For presenting, I set OBS as always on top of the presentation :

This allows me to both see the feed from OBS and control the presentation by clicking or using a wireless presentation remote to change the slides.

You might notice black lines around the presentation on the OBS feed. To remove them, you can modify the properties of the presentation tab :

Finally, you can either use this feed as a virtual webcam by using v4l2sink (which needs to be installed separately), and then selecting the dummy webcam in the software that you use for presenting as your webcam.