I'm doing 3- and 4-cam mixes. All cams but one are within a 12ft HDMI cable run. One cam ports HDMI-to-ethernet for about 250-300 ft run. I'm taking audio from a house system through one of the cams that is running direct HDMi to the card. I check my audio sync and it looks good. I come back and hour later and have up to about a full second of video latency. I haven't figured out how to compensate with audio delay in each cam. Should I expect latency and frame sync issues with such a setup?

I should mention that I set all cam inputs to not follow audio, because follow doesn't seem to work consistently. For example: If I am using audio from cam 1 with the other cam inputs set to follow, I take a video clip that is not following (set to automatically mix audio), and come back to any cam except cam 1, I do not get cam 1 audio, but get no audio. So, I set each cam input to use cam 1 audio as the audio device, and set each cam to not follow. So, I can take any cam after a video or music file and will get cam 1 audio. Does all of this make sense (including the trouble I have getting back cam 1 audio when coming from a video file and taking for example cam 2)?

Back to my original question, is there any explanation for the video latency I am experiencing?

I know this is a confusing set of problems. I hope I've been somewhat clear, and I thank you for any help.

* I'm only using audio from cam1.

* I am taking the feed into cam1 for three reasons:

1) Convenience. I receive a balanced XLR mic level output and run a cable to balanced XLR input in the camera.

2) Reduce chance for introducing noise in by-passing USB or line-in interface on computer

3) Allow easy control of levels on the fly by cam1's operator (no need to adjust levels on an audio mixer).

* There is different latency issue on different cams, I believe. I am attempting to adjust the delay for each camera in the vMix audio mixer. If I dial in the cam with the long run the others seem to need a different delay setting.

I'm sitting in my studio trying to replicate the problem and can't. I have two cams running in with 12' HDMI and one running with 150' of CAT6 between two 12' HDMI. All cams sync fine with no appreciable latency. I get to the remote site and the problem appears. It also looks like the latency may be drifting over time. Is that possible?

Your questions to me bring another question from my side. Does going line-in or USB from an audio mixer to computer differ from the camera input approach I'm using differ in latency considerations. Is there some consideration for latency when processing audio through HDMI as compared with direct USB or line-in interface to computer?

Thank you very much for even attempting to help with these questions.

[I could describe my setup a bit more so you can see why I'm making the choices I am. I'm shooting municipal meetings in different venues. I set three cams. Cam3 is locked down on the dais covering the chairperson. Cam2 is locked down on the public speaker podium. Cam1 is the only camera being operated. vMix is being controlled entirely by the one shooter operating Cam1 using an XKeys XK-24 mounted on the camera tripod. Cam4 input is an external computer feeding media (powerpoint and image files) operated by a the presenter. This allows me to run a sophisticated multi-cam mix with just one shooter and no engineer. My current XKeys assignment controls 4 cams, fade, cut, 3 DVRs with preview take stop play restart, preview take and lose title with up to 15 titles. It's quite impressive to watch one person do all of this from the camera station.]

So, it appears I can't pin down the issue. I have intermittent VIDEO sync changes going on mid-production.

Recently, in a 3-cam show (recorded and run through external HDMI for live TB broadcast), I had 2 cams direct HDMI (12' cable) and one cam with a 50' cat6 run between an 12' and a 4' HDMI.

What is troubling is that about 40 mins in, one of the direct HDMI cams shifted sync (approx 500ms video delay of video). I tried turning off the cam, unplugging from the cam input, plugging back in and turning the cam back on. No joy. I had to move the audio for that cam 500ms to accommodate the video delay.

After the show, I stopped recording and did a test recording. Resetting the audio delay back to 0 for that cam threw the sync off again.

I quit vMix, restarted the computer, relaunched and the audio sync problem was gone.

I went back to my studio and ran a couple of 8-10 hour tests using the identical setup, and even going through a hundred or so cam and title switches to simulate the show environment. But there was no video frame sync issues.

I'm tempted to conclude that this is an intermittent issue for which there seems to be no cause, and for which the only solution (other than to adjust audio sync in response to discovering the occurrence) is to stop the production and reboot.

[Aside: One thing that I did not try is the "change" the input during the show, reselecting the same cam.]

Another comment is that, since it appears that the video from one cam input is being delayed, this will create some video cut problems when cutting between cams. 500 ms is quite a difference.

Thank you for your report.

Yesterday, I did a 2-cam shoot.

Cam1 direct HDMI 12' run
Cam2 125' cat6 run with 12' HDMI on cam side and 3' HDMI on switch side

Over the course of 2 hours, the video on Cam2 became increasingly delayed. By 30 minutes it was approximately 250ms and by 90 minutes it was approximately 500ms delayed.

Anyone have thoughts on how to correct the issue?

Thanks.

Thank you, SportsNetUSA for your help.

* Comprehensive CHE-1 (1080p to 164 feet)

* Yuan SC542 N4 HDMI

I would say there are only two places it could be happening....

1) Ethernet converter

or

2) Capture card..

Are you able to use a different brand of either? Maybe try a different capture card... See that that solves the issue....

Best,

Ben

One thing that is a constant in the two productions that have manifested the sync issue is that one camera was moved during the shoot. I'm not aware of any loss of HDMI connection, but can moving the cams cause latency issues with video?

To answer SportsNetUSA's question, I am using U/FTP cable. (THIS in varying lengths).

Thank you.