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Old September 21st, 2006, 07:51 AM   #1
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Decklink out of sync problem

Not sure I'm in the right forum now but here it goes.
I've recently been using my MOTU traveler as my audio output instead of my deck-link card. My computer display is sync with picture and deck-link video output is delayed about four frames.

I can delay both sound and picture using the "frame offset" in "playback control" so that the two displays match up, but now both the computer display AND the CRT is four frames out of sync with audio. Is there a workaround for this?
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Old September 21st, 2006, 09:33 AM   #2
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Quote:
Originally Posted by Per Kristian Indrehus
Not sure I'm in the right forum now but here it goes.
I've recently been using my MOTU traveler as my audio output instead of my deck-link card. My computer display is sync with picture and deck-link video output is delayed about four frames.

I can delay both sound and picture using the "frame offset" in "playback control" so that the two displays match up, but now both the computer display AND the CRT is four frames out of sync with audio. Is there a workaround for this?
As an experiment try rendering a small portion, 5 minutes or so, and see if playback of the final output file is in synch or not. Sometimes preview is out of sync a bit even when the actual editing video is fine.
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Old September 21st, 2006, 01:27 PM   #3
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Output seems to be in sync regardless of frame offset. So itīs a monitoring issue. The deck-link needs four extra frames to process playback. So it seems to me that the MOTU interface needs to be delayed four frames to match the decklink output.

My starting point is:
(Comp. monitor 0fr) (MOTU interface 0fr) (CRT from deck-link +4fr)

When I set playback frame offset to +4 i get:
(Comp.monitor +4fr) (MOTU interface 0fr) (CRT from deck-link+4fr)

So now the two monitors is sync, but sound is out of sync with both of them.
I would like all three to match up if possible.
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Old September 21st, 2006, 01:52 PM   #4
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Someone else might have some ideas but it may not be possible. Someone might have some ideas if you told us what NLE software you're using? You may just have to bite the bullet and resign yourself to using the editing timeline to work with synch and the CRT external monitor to work with compositing and colour correction.
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Old September 22nd, 2006, 02:14 AM   #5
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Final Cut Pro Studio on a G5 dual2. I guess you're right. Better use the deck-link audio outs then and delay the LCD. Thanks.
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Old September 22nd, 2006, 05:23 AM   #6
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Originally Posted by Per Kristian Indrehus
Final Cut Pro Studio on a G5 dual2. I guess you're right. Better use the deck-link audio outs then and delay the LCD. Thanks.
I'm not familiar with Final Cut but Sony Vegas suggests using "print to tape" to send audio and video to an external monitor in order to get full quality previews with proper sync etc when its really needed. I wonder if that could work in Final Cut as well?
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