'Camera Originals' out of sync in Resolve

I just spent the week doing a livestream using an ATEM Mini Extreme and two Pocket cameras (one 4K, one 6K) and when I went to re-export higher quality versions using the ATEM resolve project, when I switch to Camera Originals, the image is out of sync by two frames. I'm sure I've done this before and it hasn't happened but it happened consistently with every recording over the week. It's easy enough to shift everything a couple of frames on the timeline but I'd rather be able to make it not happen.

Any ideas what would cause this? The ATEM was definitely communicating with the cameras (camera colour correction, timecode and remote record triggering all worked fine). Could HDMI cable length be something to do with it? They weren't particularly long cables (5m) but it's the only thing I can think of. We did swap cables around for another reason on the last day and one of the cameras ended up with a shorter cable, but it happened the same.

Unless the audio was captured in camera, two frames is about as good as it’s going to get. The camera output will add a frame as will the AMP’s frame sync. The AMP output is necessarily later than the camera record so it’s physically impossible for them to be in sync at both points. If the audio was recorded in camera then I couldn’t say.

Some light reading regarding camera delay.
viewtopic.php?t=48116
viewtopic.php?f=2&t=107803

Good Luck

Unless the audio was captured in camera, two frames is about as good as it’s going to get. The camera output will add a frame as will the AMP’s frame sync. The AMP output is necessarily later than the camera record so it’s physically impossible for them to be in sync at both points. If the audio was recorded in camera then I couldn’t say.

Some light reading regarding camera delay.
viewtopic.php?t=48116
viewtopic.php?f=2&t=107803

Good Luck

Thanks for responding. The sound is going into the 6K's XLR and coming into the ATEM via the camera HDMI feed. When it's just the ATEM's mp4 recordings it's all fine and in sync. It's when I switch to Camera Originals that the picture shifts two frames out of sync. When switching back and forth I can see the image jump the two frames forward and back. I notice that the audio doesn't change to link to the original footage but stays as the mp4, which presumably shows there's a discrepancy between the ATEM recordings and the originals caused by the processing as you mention? However, in the demonstration videos I can find online this doesn't happen, and the originals switch over from the mp4 ISO recordings in sync (eg, this video:

). So there's clearly something different going on, whether it's a bug in the system somewhere or a set up issue. I guess I'll go test some more and raise it with BM support.

I notice that the audio doesn't change to link to the original footage but stays as the mp4

This is the issue, for cam originals to be in sync, they must link to the in camera audio as well. The mp4 audio is post rolling shutter, scaling, frame sync, and compression.

I would think that the more common use case would be to use only scratch audio from the cam and a proper mix in the AMP. In this senario, the audio and cam original would be closer to real time sync. You’ve gone the other direction so the solution is to shift the mix to account for the processing delay or remix the audio from cam original.

Once you get into it you’ll realize there is no perfect sync. Consider that the rolling shutter alone is good for 20ms of delay. There’s only perfect sync on one line, the top line and bottom line aren’t even sync’d within the same frame.

Good Luck

I have the same issue. It's not just that the audio is out of sync, it's that the camera originals are out of sync with the ATME ISO files. ATEM audio is in sync with ATME ISO clips and Camera Originals are in sync with the camera audio. But now when you switch the timeline to "Camera Originals" it doesn't switch the audio source to camera originals. So it ends up out of sync.

The time code for the ISO files and Camera Originals are off by 2 frames. You can see in this screen shot that the timecode match, but the movement in the hands doesn't line up.

I never noticed this issue before, so I'm pretty sure it's new. If the HDMI delay is what's causing it then we need to have a TC off set for video like the audio offset for Ch. 1 & 2. One way or another TC on the iso needs to match the camera.

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