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Seeking tips to help me suck a bit less with OBS Studio in a lecture hall setting. (lemmy.world)
submitted 8 hours ago* (last edited 8 hours ago) by Sterile_Technique@lemmy.world to c/techsupport@lemmy.world
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Next semester is starting up soon, and one of the most useful things I've taken to doing is recording lectures. I doubt I'll ever be able to get the quality anywhere that would be considered 'good', but I have no idea what I'm doing outside of some trial and error, so I imagine I can probably get it quite a bit better with some optimizations.

Set up... recording with a laptop, and a Ugreen 15728 to capture both video and audio. Everything's done on OBS Studio. I sit at the front of the class with the webcam mounted to a little tripod and aimed at the projector screen with the end goal of basically having narrated powerpoint presentations.

The field of view of the webcam is way higher than I need it to be, so I zoom it in by fitting just the presentation to frame in OBS... which works, but probably 75% of its resolution potential is lost to just cropping it out. I don't think anything can be done about that, since the webcam doesn't have a physical zoom and I can't position it anywhere closer to the screen than I have previously. ...and the resolution as-is comes out... okay. They're powerpoints, and with the exception of the odd bit of unusually fine font, the final product is readable, in a 1995 jpeg kinda way.

I think the real room for improvement is managing the lighting settings - the issue is that the camera is still recording the bits that aren't actually being saved, so if the room lights are on and the ppt has a dark background, it gets 'corrected' to where the light font on the page also get kinda blacked out, I think because it's compensating for the bright surfaces beyond the edges of the presentation. Room lights off with a light background ppt, it all gets white-washed. Tweaking the gamma and... backlight? whitelight? in the device-specific settings I can usually get it to where the text is readable, but again, it kinda looks like shit.

Audio... I used to have some of those interview mics for the prof to wear, which were great quality for the... like two or three? times they actually decided to wear it. They were for some reason opposed to doing that, so they'd just set it on the podium and let it record from there... and then walk all over the front of the classroom, making audio quality all over the place. Tried using the mic on my gaming headset, with the entire headset perched next to the webcam, but it captured me breathing and typing more clearly than the prof; admitted defeat on audio quality and have since used the ones built into the webcam, and they do okay, but with that same kind of barely passable quality as the video.

I've seen some optimization guides, but pretty much all of them are geared toward streaming or web conferences, not lecture halls, and their tips only yielded slight improvements.

I don't really understand what any of the settings actually do, so I just fuck with the sliders or check the toggles and if it makes it better I keep it, if it doesn't I put it back... but I'm probably doing something in a stupid order or overlooking a whole category of settings. Literally just figuring this all out as I go - no prior experience with this or similar software.

...I know my recording conditions and equipment are all far from ideal, but I do share these recordings with my classmates, so if any of know any optimizations I can make with the tools on hand, please let me know!

Thanks all!

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[–] Brkdncr@lemmy.world 1 points 2 hours ago

Get a dedicated audio recording device. They are under $50 and are designed for this purpose.

[–] Nils@piefed.ca 2 points 5 hours ago* (last edited 4 hours ago) (1 children)

I recorded a bunch of lectures, either as student or as presenter.
For what you are doing, OBS (or any other software) would have to do miracles to make it any better.

Since you are doing this for yourself, and you are just recording it for later study.
I imagine you do not have the university endorsement or do not have access to the university AV tools in the classroom.
But there are some small things you can do to increase substantially the quality of your recordings.

  • If you have permission to record the class, ask the teacher to share the presentation slides with the class. Having the source will give you the best visual quality.
  • If the teacher moves a lot, ideally you want a lavalier mic, but I understand you do not get the teacher's support for that. So, ask for other students to record the class on their phones as well. Multiple sources will give you both best audio quality and a backup if any fail.

There are a few ways to go from here, in class, you either:

  1. OBS + real slides + base audio (no need for camera video input): ask the teacher to use the slides from your computer (and plug your computer to the projector), this way you can record the best visual quality + baseline audio.

edit: if you have the slides before the class, and the teacher does not want to use your computer, you can still do this, just make sure you pass the slides when your teacher does on their computer.

[OBS ]You have to set one video source to your slides, and use mic from whatever is better: notebook or webcam.

  1. Or record from your computer, like you are doing so far. (more work later)

[SLIDES] if the teacher did not give you the slides, ask to take pictures. This way you can make sure they are good without struggling with room lighting, shadows, people moving in front of the camera and so on. Your phone will do a better processing of the pictures than a webcam will do, and you do not need to wo

  1. Record from a phone with a tripod. (some work later)

It is similar to 2. But the truth is, most phones do a lot of the preprocessing for you, without having to worry about tweaking things.
With a computer, it is not just the recording software you need to worry about, there are so many variables at play and it is nice to read that you are getting aware of those. On a phone, most of those things are taken care for you.

Your only worry would be the battery usage.

After class, get the audio from other students, and pictures or slides.

Use a program to edit video. Like Kdenlive and add the audio tracks and slides to it. You can use the video editor to sync audio and sync visuals. Or use any other tool you prefer.

You want to sync the better audio with the baseline audio you recorded with the slides. Then pick the best audio from each recording you have from other students.

If you did not record OBS with real slides. You probably have terrible visuals, but at least you have an idea when the slides are changed.

Use either the slides provided by the teacher, or the pictures you took for the visual. And match the changes.

I imagine you don't want to a lot of work later and have the final product at the end of the class. But the easiest/cheapest way to have a good result would be a BT lavalier mic on the teacher + slides coming from your computer.

The second would be recording from a phone on a tripod.

Anything else that would not involve work after, would require more endorsement from your uni and your professors.

[–] Sterile_Technique@lemmy.world 1 points 3 hours ago

I imagine you do not have the university endorsement or do not have access to the university AV tools in the classroom.

I get the prof's individual permission to record. I don't have permission from the school at large... but I don't necessarily need permission to do something like shove a cable into a free HDMI port, assuming there is one. At least until IT sees it and chews me out.

Prefer not to do any post editing - I've had to a few times if I forget to pause when one of the profs or students goes into story time mode and starts spilling a bunch of personal details. It's nursing school, so those moments are usually kinda sensitive so I make a point to NOT save or upload those moments. Anyway, just going in after the fact to delete the 30 second chunk takes no time at all; but then exporting the video project back into a video format I can upload can take an hour or two... and I get home from class at like 10pm so I don't want to start an hours long project at that point. The upload itself takes more time than I'd like, but there's usually enough to do to keep me busy during that time getting all my stuff ready for work the following morning.

Slides from my comp would be a good option for most of it - annoyingly they so use some web-based presentation software sometimes. Another poster had a similar suggestion there, which has me wondering if I can link up the two comps via cable, treating theirs as an output and mine as the input, then record their screen with OBS. That would also allow me to position the webcam a lot closer to the podium itself for use solely as a mic, so that might be a two-birds-one-stone solution.

Record from a phone with a tripod

That's what I did before I got the webcam. Quality was great, but you called it: battery. They're evening classes that run 3.5ish hours, so with a good dent in the battery already just from being in my pocket at work all day, even having the phone plugged in while recording it would still die about half way through the class. It was also weird with recording length... after iirc 45 mins or so, it would just stop and save what it recorded as-is, so I'd have to (often fail to) remember to start another recording when it did that. Then stitch them together later with OpenShot, which again adds a super lengthy export to the whole project.

audio from other students

I wonder if my own phone would work for that. Battery/video recording was a no-go, but I imagine audio recording can be done with the screen off and is a less power-hungry function, to it might be able to just passively record audio. That's a different app too, which hopefully means the 45 min thing isn't a factor. Would still need post editing, but would be nice to at least have it as a backup. I have had a few times where something happened and the audio just cut out for like 20 mins randomly.

I'll see what they let me do with the slides. So far the profs have all been okay with recording, so I'd be willing to bet they'd be on board with trying these kinds of workarounds.

Thanks!!

[–] sramder@lemmy.world 2 points 5 hours ago

Check out adding video filters too; compressor, equalizer and gain may help. There’s a bunch more on github, unfortunately I can’t think of anything that adapts to all the situations you described, but you could have more than one instance of your capture device set up, one for room lighting on and one for off.

[–] Nawor3565@lemmy.blahaj.zone 4 points 7 hours ago (2 children)

This may be a silly question, but are you streaming the PowerPoint to the projector from the same laptop you're recording on? If so, you can just use OBS to record the screen directly while it's also on the projector

[–] Sterile_Technique@lemmy.world 1 points 4 hours ago

are you streaming the PowerPoint to the projector from the same laptop you’re recording on?

Negative - prof has a campus-owned comp up at the podium running the ppt, and I do the recording on my own laptop in the student seating area. Where I sit is pretty close to the podium though, so you gave me an idea: I'm wondering it I can just run a cable from their comp to mine, and use OBS on my comp to record their video output... only potential snag would be the availability of a free video port. And whether two computers will even play nice with eachother when connected like that - I've never tried it. I'll look into that!

I think I even have a HDMI to USB cable somewhere, wonder if that'd do the trick.

[–] sramder@lemmy.world 2 points 5 hours ago

Even if not, why not? Capture the application window and just use the webcam for audio (if there’s no option for a lavaliere microphone). There’s numerous advantages; smaller output files, cleanest possible video, lower system resource use…

Might be able to use the laptops mic for audio to, or as a backup track.