NDI video and USB audio out of sync

[elNehee]

Hi every one.

I have a small setup for a church. We have no internet connection on the temple. We record the service and when we get home, the service is uploaded to YouTube.

1. We have a PTZ NDI camera connected directly to the Laptop. Works fine on OBS. The video feed from the IP web-page from the PTZ camera runs with no latency. The video signal is the same on NDI Video Monitor.
2. Also a XAir18 from Behringer and the audio we get goes to the computer through USB.

That is all we need.

The OBS setup in NDI video source is:

Bandwidth: Highest​

Request hard. acc.: ON​

Latency mode: Low​

When the recording starts the audio is synchronized. But after a few minutes, the video gets out of synch and much after from the audio.

What can I do to get a synched audio and video all through the recording?
I have tried to capture the window from NDI Video Monitor, but is the quality the same?

 

[Lawrence_SoCal]

Hi every one.
I have a small setup for a church. We have no internet connection on the temple. We record the service and when we get home, the service is uploaded to YouTube.

Welcome, and you are not the first in that situation

1. We have a PTZ NDI camera connected directly to the Laptop. Works fine on OBS. The video feed from the IP web-page from the PTZ camera runs with no latency.

there is ALWAYS some latency. that it is low enough for you not to notice/care... that's great

2. Also a XAir18 from Behringer and the audio we get goes to the computer through USB.

Beware USB hubs, USB Root hub, etc. I'd recommend using a CPU connected port (vs chipset, if possible)... model specific detail.. and even then not always easy to figure out

When the recording starts the audio is synchronized. But after a few minutes, the video gets out of synch and much after from the audio.

That usually indicates a computer that is getting overloaded. and then Windows audio subsystem is NOT known for its real-time processing consistency... so can easily get out of sync
- so check for thermal throttling on laptop (I'm not aware of a general approach, tends to be model specific)
- ensure you are not CPU bottlenecking with your settings/load

What can I do to get a synched audio and video all through the recording?

Laptops, designed typically for battery life, tend to be pretty poor at the computationally intensive real-time video encoding, especially if you don't have a highly efficient video encode/decode offload chip (usually GPU). Laptops that can handle sustained high CPU load tend to be really expensive professional mobile workstation models (not retail/consumer models)... but it depends on specific settings, workload, and environment

making sure laptop thermal management system is free of dust/lint would be a first step. a fan that works with specific model laptop for extra cooling might help. Or you may need to lower your settings on Recording... or get a better laptop? depends