Hi everyone,

First time poster, been using vMix for a number of years at a novice-intermediate level.

We are experiencing an issue streaming to YouTube with audio & video drifting out of sync the longer the stream goes for.

Using a 4G service with quite limited bandwidth (10/10 Mbps) but

YouTube stream 4Mbps, 128kbps audio, 1080, 25 frames

• Blackmagic Design Quadlink with 1 HDMI input (MAIN video source)
  
• Single iPhone with NDI|HX over wifi

• Youtube stream health reporting "excellent"
  
• Normal Latency setting

Screenshot 2025-06-07 145433.png (82kb) downloaded 20 time(s).

The Audio and Video from the vMix Output sync perfectly, but as the stream goes on, they are drifting into the 1-5 second range when watching on YouTube.

We set Stream Delay to 0 seconds (it was set to 5 seconds, but no one knows why) and that appeared to improve performance. This aligned with the comments from our audience for such a high delay.

The rest of the settings are as suggested on the vMix KB article https://www.vmix.com/help27/StreamingQuality.html

statistics.png (70kb) downloaded 24 time(s).

Ignore the other 2 iPhone/NDI they are not broadcasting.

It's in a church/seminar setting, no camera movement. Which we've done hundreds of times before, but in our most recent streams this ""out of sync" issue is very noticeable.

Any thoughts or suggestions? Or more info I can share?

Thanks

CWA