One second video lag: how prevent/detect/cure?

[dtgriscom]

I'm using OBS Studio to feed NDI video into a Zoom client for a hybrid church service.

Video path: PTZOptics camera => NDI => OBS => Virtual camera => Zoom

Audiio path: Microphones => Mixer => USB A/D converter => Zoom

Last week, when reviewing our Zoom recording, I found that the camera video was a full second behind the mic audio. Nothing else was misaligned, so I'm pretty sure the problem was in the "NDI => OBS => Virtual camera" path. The lag seemed to stay constant across the one hour service.

Questions:

• What might have caused this?
• How could I detect it (other than having someone on Zoom cue me in)?
• How could I prevent it?
• If I detect it, how could I cure it (without rebooting everything?)

System details:

• Windows 11 on a Dell Intel Core i7 11700 2.5GHz
• nVidia GeForce GTX 1660 Super video card
• 16GB RAM, 500GB SSD
• All networking is wired 1000BASE-T

Thanks,
Dan

 

[DaveyRT]

I have the same issue. What I've found out so far is OBS necessarily has to process the video to then direct to the virtual camera, this does introduce latency into the video stream. Virtual camera does not support audio as far as I am aware, happy to be corrected on that as it would solve my issue. The audio however does not undergo the same level of latency in it's processing and hence is ahead of the video on Zoom or in my case Skype.

I have read that using Voicemeeter in Windows can be used to add latency to the audio but not tried this myself as I run Linux and that's not in the Linux repository. Any Linux readers out there Pulseaudio does not work.

The main issue is in OBS in that you cannot select an audio source for the audio and add latency as you can if you stream to an output.

Please please please feature request begging here.

Hope this helps you out a bit.