Ultrastudio Mini Recorder audio delay?

Hi folks,
We have an ATEM 1 M/E (HD version) going to multiple locations:

• Broadcast Room monitor: ATEM HD-SDI Program Output to HDMI display monitor via BMD HD-SDI/HDMI micro converter.
• Local Recording iMac: ATEM HD-SDI Aux 3 Output to 27" 2017 iMac via BMD Ultrastudio Mini Recorder (requires an additional Thunderbolt 2 to 3 converter). Recording to MP4 with OBS.
• Teradek Vidiu Streaming Box: ATEM HDMI output straight to Vidiu HDMI input

We've noticed that, while the audio sync on the YouTube livestream (Teradek Vidiu) and the Broadcast Room Monitor (which we use to manually dial audio sync in) both match up perfectly, but the iMac local recording has additional audio delay that we have to adjust when editing the video. Prior to purchasing the iMac, we were using an HP Z400 with Decklink SDI card or USB3.0, neither of which had this issue.

Is this additional audio delay a known issue with using the Ultrastudio Mini Recorder on Thunderbolt 3-equipped Macs that require the TB2/TB3 adapter? If so, are there any solutions to this or alternate HD-SDI to Thunderbolt 3 input adapters that might help? Or possibly settings within OBS? I don't *think* I can adjust audio delay while recording, but even if I could, it's got too *much* so I guess that wouldn't help anyway, unless you can send audio into the future lol.

Thanks,
Jeff

Have you tried recording with any other software other than OBS? Curious as to whether this might happen with other applications as well, or if the sync issue is only with OBS recordings... Maybe try Blackmagic Media Express or download a demo version of Wirecast to see?

We use the Ultrastudio Mini Recorder to feed live streams to Wirecast and OBS using a MacBook Pro laptop and have had a few more issues with OBS than with Wirecast in general... though admittedly we don't record the streams live using either application. That said, the general issues we've seen tend to be around having enough ram / processing power to support the level of stream that we're trying to encode. We've not run into much in the way of audio / video syncing issues.

Hi Brett,
I have not used Media Express regularly since upgrading to the iMac but will try Sunday. When we had the HP Z400, we had used Media Express, OBS and Vmix and audio syncs on all those were the same as our livestream and lobby overflow.

Thanks,
Jeff

Hi Brett,
Forgot to update this on our findings. We tried MediaExpress and it was the same thing, so we determined what we're seeing is additional video processing delay from either the Blackmagic Ultrastudio Mini Recorder, the Apple Thunderbolt 2 to Thunderbolt 3 adapter we have to use to connect the Ultrastudio to the 2017 iMac, the Thunderbolt 3 (USB-C) iMac internal conversion or some combination of the 3.

We did find that there is an audio delay adjustment in OBS and have experimented with that the last few weeks (currently set to about 30msec), however, our office has reported that now the audio delay is inconsistent and they can no longer just offset the audio track as a whole as they did before to correct it (this is for about a 30-45 minute sermon).

I have not been able to find a similar audio delay adjustment in Media Express. I do know that we did not have this issue with the old HP PC setup, with either Vmix, OBS or Media Express, and regardless of if we were using the ATEM SDI output to the PC's Decklink SDI PCIe card or the ATEM's USB3.0 feed to the PC's USB3.0 PCIe card.

Jeff