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AJA IO HD Varicam issue

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Shane O'Sullivan
AJA IO HD Varicam issue
on Aug 31, 2009 at 9:50:22 pm

Hello,

My first post here. I'm digitising Varicam rushes shot at 720/25P over 60P with FCP 7, an AJ-HD 1400 and IO HD via Firewire on an Imac. The aim is to digitise to 720/25P or 1080/25PsF, so I can intercut with previous 25P rushes shot on the HDX900, which wasn't available where we shot.

Page 6 of the 1400 manual claims "720/25P over 60P sources can be converted to 1080/25 PsF" but Panasonic UK can't tell me how to do it and the manual has no specific instructions.

So I hired an IO HD and modified the AJA 59.94 Capture pre-set for 25 FPS and asked it to remove the extra frames. It seemed to capture okay, at first, but when I checked the captures, there is a slow but constant audio drift.

In Quicktime, the FPS on the captures reads 24.99, 24.98, 24.97 but never exactly 25. So there's a fractional difference in frame-rate between video and audio. So if it's 24.99 and I speed up the audio by 100.041% (25/24.99) to compensate, it's back in sync but I can't understand why this drift is happening.

The 1400 and IO HD are connected by a BNC for the SDI port and a Sony 9-pin connector.

At the moment, I'm digitising everything at 59.94 as a workaround until I can find a fix that will do the pulldown to 25 accurately. The Panasonic FRC only converts 59.94 to 29.97 or 23.98, not 25.

Any help very much appreciated!

Best,
Shane



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gary adcock
Re: AJA IO HD Varicam issue
on Sep 1, 2009 at 3:13:27 pm

[Shane O'Sullivan] "So I hired an IO HD and modified the AJA 59.94 Capture pre-set for 25 FPS and asked it to remove the extra frames. It seemed to capture okay, at first, but when I checked the captures, there is a slow but constant audio drift. "

thats because you screwed yourself.

to shoot 25p with the varicam, you need to set the system to be 60fps not 59.94

have you tried conforming your clips to be 25.0? open each clip in Cinema tools and use the conform function to force the file back to 25.0 from the 24.xxx that it actually is.

gary adcock
Studio37
HD & Film Consultation
Post and Production Workflows for the Digitally Inclined
Chicago, IL


http://library.creativecow.net/articles/adcock_gary/AJAIOHD.php




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Jeremy Garchow
Re: AJA IO HD Varicam issue
on Sep 1, 2009 at 3:30:04 pm

Also, you can take the tape out, set the deck to 24/25 mode, set the 720p out to 1080i and you will get 1080 psf out of the deck.

Jeremy


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