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Timecode inconsistencies.


jason porter

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Post says they have inconsistent drift between 2 * Panasonic 3100's and my Nomad.  "Drift" is typically 1-3 frames, and it varies from device to device (sometimes cam A and sound are locked, sometimes cam A & B are locked...etc.)

Gear is -

Nomad

SB3

Mozegear Q28

2 Panasonic 3100's

Nomad 23.98

Cameras 23.98

Sync boxes xJammed to 29.97

 

Post can't seem to figure it out, does anyone have any insight to what it could be??

 

Thank you

 

Jason

Edited by jason porter
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Is it drift or offset? Drift is a problem, offset is something that will occur with any camera system and any timecode system. Some more than others.

The only difference is that some whiny post people make phone calls and send emails and complain about it, and some just get on with their jobs and leave us to do ours.

The sooner we stop making this our problem, the better off we'll all be.

My .02

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The problem seems to bounce around from device to device...which I find strange. There doesn't seem to be a consistent offset, but the difference is always 1-3 frames.

Post said the same- they can deal with it, but we just want to make sure we are doing everything we can to get as close as possible to "synced"

The camera rental house suggested it's because I am using 2 different models/brands of sync box...I don't think theory this holds water.  They also suggested that I not xJam the sync boxes and just go 23.98...but I was under the impression that the Pannys want to see 29.97 only at the TC input.

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Hi Jason. FWIW when ever I'm paired with a Panasonic 3100, 2700 or HDX I set my recorder to 29.97 and sync my ambient tiny lock it to the same. Panasonic native recording frequency is 59.94 and due to the math stuff, it likes 29.97 throughout. I've never had any issues doing this. 

Thanks Edward, I may try this.

For what it's worth, all 3 devices look synced throughout the day (as far as a human eye can tell).

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Keep in mind (and I believe this is the case -- someone correct me if I'm wrong) that when you transcode time code, it grabs the code on a full second mark.  This could account for some discrepancy.  I'd definitely try it the way Edward stated.  I agree that your recorder should be set to the same rate as the boxes.

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These Panasonic cameras are a prime example that illustrates that Time Base, Frame Rate, and Time Code are actually three different things.

I believe for the cameras under discussion, the Time Base is 59.94, the Frame Rate is 23.976, and the time code is 29.97.  It has to do with how Panasonic initially stores the frames and then how it extrapolates the necessary frames to achieve the desired frame rate.

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The one exception to the rules for Panasonic are the new Varicam 35, which will do true 23.98 and 24.00fps timecode and framerate.

I would do a workflow test and see how it works with 29.97 timecode going to everything. I would also use an SB-T assuming the Panasonics can take in Genlock reference. That should at least ensure that the cameras are precisely in sync with each other. Without genlock, it'll often slide a frame either way, meaning you could have +1 on A Cam and -1 on B Cam, meaning 2 frames of offset.

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I just heard back from post.

After the 2nd week of shooting, I starting rejamming every 4 hours (instead of 6) hoping that would help.

Post says the cameras are now "bang on" but my Nomad is 1-3 frames out, but not consistent.

We are going to try audio at 29.97 and see how that goes.

Thanks for all the insight!

Edited by jason porter
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