Audio is out of sync, arriving late

We are currently streaming from a multiple camera system routed through a Roland V-1HD, output is 1080p/59.94, into an iMac loaded with ProPresenter 7.2 to introduce lower third screens over the video. The audio and video are in sync at the iMac. We then output over HDMI via a thunderbolt 3 adapter to the Webcaster X2.

Our regular upload speed is 7Mbps.

Audio is late in the streamed video. Any ideas as to the cause?

It’s possible it could be caused by the thunderbolt to HDMI adapter, however the other possibility could still be network related. If you are using WIFI, there could be enough signal interference to cause an inconsistent signal strength. I would recommend testing Ethernet (if not already using it.) Additionally, if there is a firewall on the network, it’s possible it could be throttling the network connection enough to cause a break in the video-audio sync. One option could be to try on a completely different network to see if the problem still occurs. If the issue follows the network change it could be the HDMI adapter causing the issue, and I’d recommend testing a different adapter

Unfortunately Webcaster X2 does not have any settings to adjust the sync issue so there are no manual methods from the encoder to address.