Multi frame rate TC question

[Marc Hoppe]

I'm shooting an interview on a Canon 1D (primary cam) and the Panasonic P2 Varicam (secondary cam). 1D TC set to 23.98 being fed a scratch track from an erx from Nomad. Hardwire into Varicam. The Varicam is shooting at 23.98, but it is actually a pull down from 29.97.

When I tried to feed it 23.98 TC from the erx, I got a warning flashing. When I switched the erx to 29.97, it took the jam fine and appears to be staying in sync. We're not rolling until after lunch so I'll check back then.

My question is twofold:

1. What is happening when the erx is receiving 23.98 TC but outputting at 29.97? And

2. What will happen on the timeline when the audio files and the video files are on 2 different frame rates, but the waveforms are exactly the same?

Thanks

Marc Hoppe

[Philip Perkins]

If the files from the two cams are properly digitised they will be fine--ie "real time" will be maintained, ie sync.  The Varicam will only take ext TC @ 29.97 in my experience, for the reasons you said.  You've got clean audio to both cams, that gives post lots of syncing options.

 

philp

[studiomprd]

" What is happening when the erx is receiving 23.98 TC but outputting at 29.97? "

SMPTE/EBU TC 101:  the two non-integer frame rates are at the same speed; they line up perfectly at the :00 frame's every second.

[Marc Hoppe]

I get that Mike, but is the erx converting it, doing in essence a "pull-up" after being sent 23.98? I wasn't aware that it could receive 1 frame rate and output another, it was just something I tried and it worked.

We'll also be slating.

Thanks

Marc.

[studiomprd]

" is the erx converting it, doing in essence a "pull-up" after being sent 23.98? "

not really...

while I have no technical knowledge of the specific camera involved,  the device is jamming on the :00 frame, and counting on its own from there,(that is what "jamming" is); one device is dividing its "second" into 24 slices, and the other is dividing that same second into 30 slices.

[Marc Hoppe]

Thanks Mike, I appreciate the simple explanation.

Marc

[John Blankenship]

...

the device is jamming on the :00 frame, and counting on its own from there,(that is what "jamming" is); one device is dividing its "second" into 24 slices, and the other is dividing that same second into 30 slices.

Good description.