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Wednesday, April 19, 2017


This is a techie question for my readership.  Suppose I want to record and post on YouTube lectures involving technical materials that can only be taught clearly with the aid of visuals – diagrams or equations and the like.  My recent experience convinces me that having Staples make up big boards is too expensive, and my handwriting is now, with advancing age, so crabbed as to be virtually unreadable.  What I would like to do is this:  Prepare pages of formal materials in advance on my computer, and then deliver a lecture to a camera in such a way that with a click of a mouse, I can switch from the picture of my face [always something of a turn-off  J ] to a prepared page of material while my voice can still be heard over the projected formal material.  Then, with another click, I return to me talking to the camera.  It would of course be a big plus if, as I did this, I could deploy an arrow with a mouse to call attention to something on the screen being projected.

Intuitively, it seems this ought to be possible, but I have not a clue how one would do it.  Does anyone know what equipment I would need or how it could be done?


Chris said...

Something like this?

Robert Paul Wolff said...

That is certainly a step in the right direction. Now, how is that done? And what equipment do you need to do it?

Mazen said...

1) Instead of making boards with Staples, why don't you simply making slides with powerpoint or keynote? Just have the camera move back-and-forth between you and the screen during the lecture. This is the simplest (low-tech) option.

2) It might not be too difficult to combine video and slides using iMovie or other video editing programs (I don't know of a program that provides as easy a solution as you want).

Robert Paul Wolff said...

I tried the moving the camera solution and it really does not work successfully. There has got to be a way. Here is the question: While the mike continues to feed my voice into the camcorder, can I switch from one video feed to another -- from me to the computer and back again?

Mazen said...

Yes, now that I think of it, it should be possible. I think you need to use screen capture software (it should capture what is on your screen and your voice as well). Then you need to combine your screen capture video and lecture video using a video editing software (e.g., iMovie).

Here's how to do it on a Mac:

Robert Paul Wolff said...

hmm. All that is rather mysterious, but I have the feeling once I learned it I could do it. I might have to get a Mac, which my son, Tobias, has been urging on me for ever.

Daniel said...

I recently watched one of your Kant lectures and noticed this exact problem. Honestly I think you would have been better off just making a Powerpoint and then posting the slides in PDF form. As long as the slides are done well and you reference which one you're on, the online reader will be able to download them and then follow along just fine. The solution I saw you implementing, which was using MS Word projected onto a computer, is definitely one to avoid. But it is very easy to link to slides in the description portion of a YouTube video. Just make sure you host them somewhere that can be permanent for those who want to access them years later.

As far as the video-editing solution, that seems like overkill, but maybe you will figure it out just fine. You certainly don't need a Mac as long as you buy some screen capture and video editing software for PC. The biggest limit to video editing is not having a powerful enough graphics card onboard. Most Macs do have this, which is why they are often recommended, and their on-board editing solutions are relatively simple and easy to use (but also limiting in what you can do for that same reason).

Chris said...

Professor Wolff, there are certain screen recording softwares which will record everything going on on your PC monitor. If you had some of that software plus a webcam, you could keep a video feed of yourself going, like the man in the youtube link, and also go through a powerpoint.

So as of this moment you need a webcam, which I think you have, and a screen recording software, which are all over the internet.

Chris said...

Maybe this?

Mazen said...

Would this work?

If yes, you can send me your notes and the lecture video, and I can combine them and see if this works for you.

Unknown said...

Apowersoft is an excellent software for screen recording, it includes mouse cursor movement while recording your voice through the webcam or any other microphone input. As long as you have that software running while you film your lecture, you can simply use your computer as if you are presenting on a projector. Afterwards, you can edit the screen recordings saved with Apowersoft with your camera footage using any simple video editing software. (e.g. iMovie.)

Danny said...

'While the mike continues to feed my voice into the camcorder, can I switch from one video feed to another -- from me to the computer and back again?'

How twitch folks do it, is you have two tripods, and a volunteer to monitor the laptop and to operate the video mixer (i.e. to choose whether to use video from the camera or from the projector). In other words, you record a projector and 'the speaker', and you use a digital mixer to switch between these videos on the fly.

Unknown said...

For recording your screen, I strongly recommend OBS - Open Broadcaster Software.

Yes there are a lot of options, but you (or someone friendly) sets it up once, and then it will just work. It's free and won't try to sell you anything and it's very low latency - no lag between doing things.

It's what most Twitch broadcasters now use.

Marinus said...

I second Alexander's suggestion. The kind of thing you describe is very easily accomplished with a program like OBS. Also, because of its popularity, there are very many good guides to using it available online.

What OBS does (and other similar programmes too) is compose a video from the inputs you give it, prominently, from the screens of the programmes you tell it to look like or from a camera attached to the computer. How it would work for you is that you set it up to have two inputs, the camera and the program where you've prepared the notes (Powerpoint, Word, whatever), and while recording you tell OBS to change the video it records from one to the other. At that point the video will switch from showing you to showing the work. When you're done with that, you switch back to the camera feed.

With only a few more well-chosen mouse clicks, you can set it up so that while you're showing the formal material, there's a picture-in-picture of your face in one corner.

Robert Paul Wolff said...

this sounds really promising. I am going to look into it. Thank you.

Anonymous said...

Professor Wolff,

I'm currently listening to your Ideological Critique series on YouTube. I'm curious about your impressive library. Do you have a list of the books that you have? How large is your collection of books? I'm assuming you have some of the greatest books ever written in your collection..


Anonymous said...

The advice here seems more complex than is necessary.

This is a 10 minute job in post-processing, and in my opinion can be learned in the same amount of time.

Take your recording in whatever format on a computer. Pull it up into any video editing software, I prefer Sony Vegas but Apple and Windows both come with a built in one for free and I'm pretty sure youtube has editing software built in now as well. You can scroll through the video and overlay an image whenever you deem necessary.

As mentioned in other comments, it would be best to use a powerpoint presentation to create the slides being used.

Anonymous said...

OBS - Open Broadcaster Software is the way to go. You will also like the licensing agreement inspired by Richard Stallman of the Free Software Foundation.

I just used this today actually to demonstrate why some web page was not working. It took some time to figure out. I went to and searched for "Open Broadcaster Software" or "OBS tutorial". I found many impressive tutorials of people combining video games, camera feeds, and other displays to present a broadcast.

You may want to use OBS to capture all these inputs and then upload those files to

You may also want to use and have us comment on your presentation as it happens. Who knows, you might be a new star on twitch.

Anonymous said...

OBS is more complex than necessary? Bullshit. It's more work to do post-editing to insert slides. Besides, the video output (of the slides only, if desired) could be projected in real time while the software records the talk and is switched between the slide presentation and the video camera.

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