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How can I edt Frame Accurately to AJ-HD1700 at 59.94?

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Mark Boszko
How can I edt Frame Accurately to AJ-HD1700 at 59.94?
on Oct 10, 2006 at 5:17:16 pm

First, our system:
G5 Quad 2.5, 8GB RAM, Kona 3 (running 3.1 drivers) with Kbox, FCP 5.0.4, OSX 10.4.6, QT 7.1.1, Xsan 1.3 connected via dual fibre to shared 24TB SAN.

Now, the issue:
We have, for about a year now, had a Panasonic AJ-HD1700 deck that we have not been able to edit frame accurately to. We are editing our shows at 23.98 in FCP, and editing to tape through the Kona 3. (This issue, though, has existed since we were using FCP 4.5, a Kona 2, and earlier versions of all the other pertinent software.) I'm going to explain things as I understand them-- please correct me if I've got something wrong.

The issue seems to be that the 1700 uses a 29.97 timebase split into progressive "fields" (yes, I know they're not interlaced fields, but I don't know what else to call them, so bear with me-- if you know the proper terminology, I'd love to hear it.) So, on the TC display for the 1700 deck, you will see, for instance 1:00:00:00, then the next frame is 1:00:00:00*, the asterisk denoting the 2nd "field", and thus it goes for 60 frames-- a single timecode, then a duplicate number with an asterisk, and so on, so this is how it counts to 60 using only 30 numbers.

From what I have been told, this is because there is no 59.97 TC standard at this point, and so the approximation to 29.97 with "fields" is used. When we try to edit to tape, though, it pretty reliably slips out of sync, and so if I tell it to edit in at 1:00:00:00, it will instead start at 1:00:00:00*-- the one with the asterisk. My theory at this point is that the Kona is getting confused, and since the RS-422 standard doesn't account for there being 2 frames with the same TC, it doesn't even know it's editing in the wrong place. Of course, this seems silly-- I know I'm not the only person using this deck at 59.94, so there must be a solution that works.

AJA told us a few months ago to try, instead of using our house blackburst sync, to instead try pulling the sync cable out of the 1700 and set the Kona to free run, and that would aloow it to sync on its own, and should get rid of the problem. That did help things (as we had been more than a single frame out in the past), but now it seems to be very consistently 1/60th of a second late. I can't compensate for this with FCP's frame offset, since it only allows you to offset in full frames as it counts at 29.97, which would actually push me 2 frames out.

We're at our wits end on this, and save getting AJA, Panasonic and Apple on a conference call to battle it out, I'm not sure how to resolve this. If you have any suggestions at all, they would be most welcome.

--
Mark Boszko
Self-Proclaimed Digital Media Guru-in-Training

mark@steamermedia.com
http://www.steamermedia.com


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Mark Boszko
Re: How can I edt Frame Accurately to AJ-HD1700 at 59.94?
on Oct 12, 2006 at 8:15:11 pm

Wow! Zero repoonses!

Am I really the only person having this issue?


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gary adcock
Re: How can I edt Frame Accurately to AJ-HD1700 at 59.94?
on Oct 13, 2006 at 12:26:12 am

[Mark Boszko] "The issue seems to be that the 1700 uses a 29.97 timebase split into progressive "fields....so this is how it counts to 60 using only 30 numbers.""

Mark Panasonic issued a service note on this some time back, there is a service patch that can correct this issue- this is an older model 1700 deck ( my guess is an early "a:" model)

[Mark Boszko] " instead of using our house blackburst sync, to instead try pulling the sync cable out of the 1700 and set the Kona to free run,.... That did help things (as we had been more than a single frame out in the past), but now it seems to be very consistently 1/60th of a second late."

Drop frame vs non drop.


I have laid to tape on over 30 shows to a 1700 and never seen this issue.

contact me offline (studio37@mac.com) to talk more.




gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows


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