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Camera freezes on stream start


Camera produces an image fine in OBS when launched, but when we start our stream, the camera image freezes. We have to go into OBS to the camera source and deactivate/reactivate the camera to get the image working again. Then all is fine the rest of our stream. Anything you can suggest?

Our setup:

PT30X-NDI-GY, firmware 6.3.18

HP i7 Laptop (an older 15-as016tu, but not being stressed)

IP for commands from OBS dock control 

HDMI optical cable (30 feet) and Elgato Cam Link 4K for video capture

Camera, OBS, stream all set for 1080p 30fps.

OBS version 26.1.1 on Windows 10


Jon T.

Hi Jon,

If this is only happening when the streaming is initiated that makes me think it has something to do with the CPU usage on that machine.  Pull up task manager and go to the Performance tab and watch the CPU usage when you start streaming. 

If this is not the issue, I would test another HDMI source into the Elgato to see if has the issue pulling another source. It could just be a USB power issue. Make sure to go into Device Manager, go down to the Universal Serial bus controllers, and right click on each USB HUB, go to the Power Management tab, and uncheck Windows saving power by turning off that USB port. 

If you cant get it working correctly feel free to all in and we can troubleshoot to try and get to the bottom of it.   484 593 2584 8am to 6pm EST M-F.

Thanks for the suggestions. 

My recollection is that there is plenty of CPU headspace, but we're itching to replace that laptop with a dedicated PC. Can't find a graphics card for a reasonable price, though <sigh>.

The USB port Power Management sounds plausible to me since our stream operator sometimes has to unplug and replug that port to get things working again. The laptop does sit on and idle for at least 20 or so minutes before we start the stream. We'll try those power settings  first, followed by the HDMI suggestion.

To close the loop. We got a church donation that allowed us to buy a dedicated streaming desktop PC in our production area with a fast CPU, a GTX1650 GPU, and lots of RAM. It replaced an older laptop that shuttled back and forth from our church office to the production area for livestream services.

The USB cables are permanently attached to the new PC instead of unplugging and replugging them into the laptop. We haven't seen the camera issues with the new PC.

Faster CPU? Fresh Windows install? Dedicated USB connections? I won't complain. I'll take it.

Thanks for your help.

We got to the bottom of this. We spent a fair amount of time experimenting to figure out exactly what triggers the camera issues. It had nothing to do with the camera. The Vimeo webpages used to select the encoder when starting a live stream was the culprit.

What was happening: as you move through the Vimeo live stream set up pages, it first attempts to provision the camera for their web encoder (WebRTC they tell me). It can't and tells you another application is using the camera (that's true because OBS already has the camera). It's that conflict that causes the camera to freeze or (more recently) display color artifacts. But we never use the web encoder, we skip ahead to use RTMPS with OBS as the encoder. 

A simple disable/reenable "bounce" of the camera input source in OBS reestablishes the normal camera operation. That could be done before going live. But the long-term fix suggested (and works) is to go into Chrome settings and block the Vimeo website from accessing the camera and microphone. Now when you go through the Vimeo pages to start a live stream, you get a message that Vimeo isn't allowed to access the camera, and the camera is unaffected.

In case any of your other users see this. We wanted to get to the bottom of this because we wanted to make things easier for volunteers to operate our live streams.

Another common issue is usually related to the video card in use by the computer, if you are streaming via a PC. Generally, if everything is setup correctly, there won't be an issue. But it's not unlikely that a BIOS error would cause a GPU to not work correctly, which, in turn, can lead to further problems when the streaming application finally launches. I faced this issue from a PC streaming standpoint and was able to narrow the issue down to BIOS settings - so in case it helps someone, here's how you would troubleshoot video card errors normally.

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