OBS for Church Streaming on Laptop: Lessons Learned

[wamcneil]

Hi All,
I've been using OBS to live-stream service for a small church. I'm posting this info with my experience in case anybody like me is searching for this kind of info on OBS and budget-oriented laptops.
TLDR Summary: Laptop dedicated graphics are essentially rendered useless if you need to do full-screen capture of any external monitor (ie- capture a projection slide show)

Our A/V booth is very small and fitting a full size desktop computer was not an attractive option. I'm not live-streaming my gaming or doing other activates that I figured should load the system down, so I thought an entry-level gaming laptop with dedicated graphics (ie- with hardware encoding: NVENC) would suffice.
In fact I tested the theory with my work laptop and it handled the load just fine (6-core i7 9750h, Quadro T1000, 32GB ram). But that kind of laptop was not in the church's livestream budget...
All of the advice on this forum says "don't try a laptop", but nobody gave any details on WHY it might not work. And it DID work for me with a really beefy laptop (and if I were doing nothing but streaming, the gaming laptop would be been fine).
So I got an MSI GF63 gaming laptop with i5 processor and GTX 1050 graphics. And it didn't work so well, so I thought I would share my experience in case anybody else is on a budget and thinking about ignoring the advice to not use a laptop.
Here's the way I'm using computer to run the service and OBS.

• PTZ Optics camera at 1080p using RTSP over ethernet
• OBS is streaming to Facebook at 720p
  • OBS also recording to disk
  • OBS sending full-screen 1080p preview for remote projection
• Sound device is Focusrite Scarlett used for computer audio in/out
  • Computer is connected to sound board to feed laptop audio into the house mix
  • Sound board is connected to computer to fed house mix into live-stream
  • OBS 'monitor' feature used to feed combined audio out computer HDMI for remote projection system
• One computer monitor output is connected to HDMI distribution system to drive two projectors in church
  • Computer runs PowerPoint slide show on projectors for the church service
• One computer monitor output is connected to HDMI distribution system to drive projector and sound in fellowship hall (duplicate of live-stream)
  • OBS sends full-screen preview to monitor output for fellowship hall projector and sound system

So, here's what I found. If I was ONLY showing static powerpoint slides, the setup worked pretty well. The processor and onboard graphics would sit at about 60-75% and the dedicated graphics about 15%.
But when my powerpoint included a video, it would peg the processor AND onboard graphics at 100%, and OBS couldn't keep up. So the output would slooooow dooowwwn during the video, and then catch back up afterward. The output would skip for about a minute after the video ended and OBS struggled to catch up.
What you ask??? Why is the onboard video saturated, while the dedicated graphics just loafing along at 15%???
Good question. And here's WHY a budget-oriented laptop is not a good fit for OBS. It has to do with the way laptops handle video processes. And the dedicated graphics winds up ONLY being used for NVENC hardware encoding.
Remember the sticky in this forum on what to do if you get nothing while trying to do a screen capture with OBS on laptop? I'm not sure if I completely understand the technical aspects of this, but apparently almost all laptops are built such that only the laptop screen benefits from dedicated graphics. If you connect an external monitor, it is driven by the onboard graphics exclusively and there's nothing you can do about that. And if you want to do a screen capture of an external monitor (ie: driven by the onboard graphics), you need to restrict OBS so that it ONLY uses the onboard graphics.
So effectively the dedicated graphics is only used for hardware encoding, and EVERYTHING else is loaded on the poor little onboard graphics and processor.
If my budget setup was ONLY used for video capture and streaming, it would have worked out fine.
But here are the surprise lessons-learned for me:

• Laptop dedicated graphics are essentially rendered useless if you need to do full-screen capture of any external monitor (eg- capture a projection slide show)
• Full-screen preview is very resource intensive (sending full-screen output for remote projection was about 30% of my total load)
• Playing videos within Powerpoint slides is an incredible resource hog (this would pile on about 40% more total load)
  • Side notes on powerpoint videos
    • You've got to keep focus on the powerpoint application continuously while the video is running. So if you click on any other application like OBS while the video is playing, the video STOPS playing until you put focus back on powerpoint. This really bites and as far as I can tell, there is no way around this in powerpoint.
    • Now I have our videos provided separately from the powerpoint slides. Playing the videos in another application like VLC full-screen is much more efficient and doesn't hijack the computer while the video is playing.
    • VLC has some options that make a video launch straight into full-screen on a pre-designated monitor.

So, sorry for the long post. Hopefully this helps steer someone in the right direction.
In my experience, a budget gaming laptop with NVENC can run OBS just fine as long as you're not asking it to do much else.
Cheers,
Walter

 

[wamcneil]

And another followup note: I found that HP and Dell have entry-level gaming desktops in a relatively compact chassis. These are available with i5 9th gen processor and GTX 1660 graphics at a cost comparable to entry-level gaming laptops. Both of these had a price-point and size that worked for me.
There are more compact options available with GTX 1660 or better graphics, , but everything I found that was significantly smaller was much more expensive.