How to Combine Your Slides and Webcam
If you’re wondering whether your students are paying attention during your online lectures…they’re not.
“I’m waking up and then falling asleep again in Zoom classes.” – Xavier University Student
To be clear, this isn’t your fault or your students’ fault. The way screen sharing works on video conference platforms (where students see your slides fullscreen but only a tiny thumbnail of your webcam) means it’s near impossible for anyone to pay attention during a slide-based online lecture.
But you can easily change that. Using free, open source software, you can do what news and TV shows have done for decades:
Show facts and faces side-by-side.
When students can see your face, they can read your non-verbal cues to see how passionate you are and how important a subject is. Combine that with the fact that human faces are naturally engaging, and you can start lecturing online in a way that’s not only more interesting to your students, but more fun for you – at least it has been for me :).
For everything you need to combine your slides and webcam, open the free instructions below.
How to Combine your Slides and Webcam
We will show you, step-by-step, how to combine your slides with your webcam to create engaging experiences for your students when listening to your lectures online.
Step 1: Create Test Slides
Create slides that have a green screen built into them, which means you will add an area (your green screen) that you will eventually replace with a video output (your webcam). To do this, in PowerPoint:
- Click “Insert” on the top menu
- Click the “Shapes” option
- Select the square shape option.
Draw a square box over half of a blank slide. Then fill that box with a bright green color, using RGB color codes 0 for Red, 255 for Green, and 0 for Blue. You then want to send your green screen to the back by right-clicking, and selecting “Save to Back” from the menu that pops up. Finally, move the text box on the slide to the other half of the slide so it does not overlap with the green screen half.
Keep the PowerPoint window open and move it to the left half of your screen.
You can also download sample slides here.
Step 2: Create Video Output
Now download OBS Studio, which is free, open-source software that will enable the green screen effect. You’ll first want to set up your video output in OBS. To do this
- Click on “File” in the top left corner
- Click on “Settings” in that File menu
- Click on “Video” in the menu on the left
- In the top box labeled “Base (Canvas) Resolution”, make sure it is “1920 x 1080”
Now you want to add a new video source. In the “Sources” box at the bottom:
- Click the + button
- Click “Video capture device” from the menu that pops up
- Name the device in the top line of the box that pops up (“Webcam” for instance)
- Click “OK”
- In the next pop-up box, select your webcam in the “Device” box
- In the “Resolution/FPS Type” box, if your webcam allows output at different resolutions, you will want to select the same resolution you selected in the OBS video output (in this case, “1920 x 1080”)
- Click “OK” and you should see your webcam output with a red box around it in the OBS window.
Next, you want to add a specific window to your OBS video output as a source. In this case, that window will be your PowerPoint slides. To do this, in PowerPoint:
- Click on the “Slide Show” menu at the top
- Click on the “Set Up Slide Show” menu
- Click on the “Browsed by an individual (window)” radio button
- Click “OK”
- Start your slideshow
Next, you want to tell OBS to put the window showing your PowerPoint slide on top of the output from your webcam. To do this, in the Sources box of the OBS window:
- Click the + button
- Click “Window capture” from the drop-down menu
- Name the output (maybe “Slides”)
- Click “OK”
- OBS will provide you with a set of windows you can potentially capture and lay over the webcam output. Click the drop-down menu labeled “Window” and select “PowerPoint Slideshow Presentation”
- Click “OK”
You will now see the slideshow on top of your webcam output, with a red box around it. Drag the edges of the red box to make the slide show window the entire OBS output. You can then resize the original slide show (on the left half of your screen) to get rid of any black bars or elements around the edges you don’t want visible.
The next step is to get rid of the green screen. To do this:
- In the OBS window, in the Sources box, right-click on the “Slides” source (or whatever you named your slides file)
- Click “Filters” from the drop-down menu
- Click the + on the bottom left of that window that opens
- Click on “Color Key” from the drop-down menu
- Name the Color Key in the box that pops up (for example, “Greenscreen”)
- Click “OK”
You will see that the green part of the slideshow screen has been eliminated. If you see a slight green line between the two halves of the slides showing in the OBS window, you can slide the “Similarlity” slide to the right until that disappears. Click “Close” and you should see the right half of your slides visible and your webcam visible on the left half of the OBS window.
The next step is to move the webcam window. Click and drag the webcam output to the left until your face is positioned in the left half of the OBS window.
Now you can advance the PowerPoint slides by clicking on the Powerpoint window, and advancing the slides as you normally would. What you will see is in the OBS window, on the right side, the slides are advancing while the webcam output stays in place.
One advanced step is to create an audio source in OBS. To do this:
- Click the + button in the Sources box at the bottom.
- Click the “Audio Input Capture” in the drop-down menu
- This will be to capture your microphone, so name it accordingly (i.e., “Microphone”)
- Click “OK”
- In the pop-up window, select whatever microphone you normally use, then click “OK”
This isn’t necessary to capture the slide and webcam videos in OBS. However, you also have the capability to record videos in OBS. If you wanted to record any lectures/lessons in OBS, now you would have the capability to capture the screen and your audio – you would just click the “Start Recording” button in the Controls box in the OBS window.
Step 3: Send Video Output
You now have OBS set up to produce the output you want. The next step is to send that output to the places you want it sent. You have two basic options to make this happen.
Option 1: Virtual Camera
OBS as a default uses your virtual camera; it takes your OBS output and makes it look like it’s a normal webcam to any video conferencing software (Zoom, Webex, etc.)
In OBS, select the “Start Virtual Camera” button by default under the “Controls” box in the lower right hand corner of the OBS screen.
NOTE: If you are using a Mac, you may need to delete a previously downloaded Mac plugin. Follow these instructions to do so.
This has now enabled your virtual camera to send the output to any service that wants to use your camera. To check whether this is working, open your video conferencing software (i.e., Zoom, Webex). Start a new meeting. Select OBS as the video output (instead of your normal webcam).
If your video conferencing window overlaps with your PowerPoint window, it will show up in your OBS output window. To prevent this, drag or shrink your video conferencing window so it does not overlap with your PowerPoint window, so in your OBS output window, all you see is your webcam output (your face) and the non-greenscreen part of your slides.
We recommend you downsize the OBS window and enlarge the video conferencing window. But when doing this, make sure nothing overlaps with the PowerPoint window.
Click the appropriate buttons to start your video in your video conferencing window. The camera you want to select in your video conferencing software is the “OBS Camera”. You should see the OBS output is now showing in the video conferencing window.
Option 2: Screen Sharing OBS Preview Window
In the OBS output window, right-click in the grey section to the left of your face. Select “Windowed Projector Preview” from the drop-down menu. What this gives you is a window that previews the OBS output. You can adjust that window size to eliminate any sort of black bars or “blank” space around the edges.
In your video conferencing window, instead of using “OBS Camera” as your video output, you can select “Screen Share” (in Zoom) and select the “Windowed Projector Preview” screen. You will see a green box around the “Windowed Project Preview” box, which means that is what is being sent out via the video conferencing Screen Share.
Step 4: Add Some Flair to your Slides
Just as you do in class, you want your presentations to be dynamic and engaging for your students. You can do this by adding small elements to your presentation.
You might add your school colors to the presentation. Use larger, more interesting fonts. You can also experiment with moving the greenscreen portion around on your slides to shift where your webcam output shows up. Maybe you add that to the bottom corner of your slides, and you can look up at the text as it flies into your slides.
You now have the capability to create dynamic, engaging presentations for your students. Experiment with what OBS can do to bring your lectures and presentations to life!
13 thoughts on “How to Combine Your Slides and Webcam”
Thanks for a great tutorial.
I wonder how you make sure your video window follows and rescales to fit the changing green screen? (for example when you switch from the first slide with half screen being green, to another slide with a small circle in the corner)
To accomplish that, I use two different “Scenes” in OBS, each with their own camera placement, and switch between them.
I’ll give that a try.
Justin – I’m getting everything set up and have no problem setting up the various scenes in OBS, but then how do you “advance” the slides and ensure the proper animation and functionality of your slide presentation “follows” you scene to scene. Do you have to advance the slide first and then the scene or switch scenes and then advance the slides? Want to make sure it’s seamless for what the audience (ie my students) see.
Thanks so much for asking this, Alon. I got OBS set up on my Mac with a virtual cam and all the workarounds, but was really stumped on this one. I’ll give it a try with multiple scenes. That’s really helpful.
Hi Justin, thanks for the helpful tips! Following your tutorial, I tried setting up some slides with a green screen in OBS and it worked fine. But when I tried feeding it into Zoom via OBS virtual cam, the resolution is terrible. I am using Auto settings in Zoom. May I know how you managed to retain a clear resolution of your slides and video from OBS to Zoom? Thank you!
Might try making sure Zoom is set to use HD video, and make sure your OBS video output is at least 1280 x 720.
Keep us posted!
Hey Very clear tutorial. But I fail every time at the point where the green screen is meant to disappear. I have set up my slides with powerpoint and with keynote. Ive triple checked Ive done everything you say and still when I click ‘Close’ after setting the filter the green is still there and I can’t see the camera. Baffled!
Do you use Streamdeck to switch from scene to scene?
I use “StreamControl” an app that turns your phone into a streamdeck style interface.
Excellent a very clear set of instructions.
Will this work with Blackboard’s app, Collaborate? We can’t use ZOOM at our school.
I haven’t tried it, but my assumption would be yes.
If you give it a shot, please let us know how it goes!