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Here’s a baffler…
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Well..maybe its a lunar ,crystal sync, kryptonite, Mayan calendar-end-of-the-world thing. Are you near Area 51? 🙂
Sorry I couldn’t resist.Seriously this is a real stumper.
Hmmm.
How much footage? Can they be logically broken up into segments/songs/interviews and recapture smaller clips?j
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[avidzombie] “Well..maybe its a lunar ,crystal sync, kryptonite, Mayan calendar-end-of-the-world thing. Are you near Area 51? :)”
I finally figured out that there was a ripple in the time-space continuum here today in Brentwood. I called Apple support to see if that was covered under AppleCare support, but they said I needed AppleCare Professional Video Support. Jeeze, you know they really should divulge these things to customers at time of purchase. I mean heck, you’d think something so basic would be covered by the manufacturer. I think Apple should really be ashamed.
David Roth Weiss
Director/Editor
David Weiss Productions, Inc.
Los AngelesPOST-PRODUCTION WITHOUT THE USUAL INSANITY™
A forum host of Creative COW’s Business & Marketing, and Indie Film & Documentary forums.
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[David Roth Weiss] “I finally figured out that there was a ripple in the time-space continuum here today in Brentwood.”
I was going to suggest that you check for inordinately high tacheon (tack-ee-on) emissions in your area, but you’ve obviously done your research.
– Don
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Fascinating! I wonder if this could happen with two P2 cameras or two hard drive recording cameras.
Here’s my theory. The audio sample rate really is off by some tiny amount but it’s too small to show as anything different than 48K in the item properties–a rounding error if you will. As to why that would happen I have no guess. I’d be suspicious of the FireWire bus though.
Please tell us the answer if you find it.
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[David Roth Weiss] “[Arniepix] “Does this drifting audio stay in synch with the picture of that camera?”
Yeppers!!!”
[David Roth Weiss] “[Sean ONeil] “What about the picture? Does the video for both cameras stay in sync?”
Yep!!!”
Hi
Paradox time…
If each camera’s audio is in sync with its video, and
If both camera’s audio drifts sync with the other, then
Both cameras video should, in maintaining audio sync, not remain matched.So a timecode reader filter on each cameras video should determine if there is the same frame count = duration on each camera shot from clapper board to something equally determinable at the end of the audio.
If it isn’t then the two cameras are running at different frames/sec rates – which is a mechanical head-rotation difference, and nothing to do with audio sample rate.
Different battery-charge levels or something, affecting each camera’s head-rotation ability to keep up with its internal crystal-sync…
On the other hand if there is the same frame duration for the two cameras over the hour+’s video duration, then something is indeed happening to the audio sampling rate.
Does Cinema Tools or some other software have a ‘Conform to Frame-rate’ facility?
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Global Warming.
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[David Roth Weiss] “So, I sync ’em up to cut multicam and whatta ya know, they only stay in sync for a few minutes before one camera’s audio appears to lag behind the other,”
How many minutes before the drift?
There’s the time-honored “Capture in short segments” technique that has saved many a sync issue in the past.
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AND…
I’m still back at why you don’t just PLAY both tapes at once and see if you get the drift on PLAYBACK, or if this is strictly an in-the-Mac-or-Hard Drive FCP problem.
If they drift just PLAYING, then its a tape problem and we know not to chase it in the Mac.
If no drift just PLAYING, then we can look at capture or FCP issues.
Play one tape on a deck, the other on a camcorder, or any combo of the two.
We could even see if CAPTURING from a CAMCORDER will change things, but we need more info so we know wherein the problem lies.
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Timing is probably provided within the camera by quartz crystal oscillators. Power supply voltage variation and aging, as well as temperature, can affect the crystal.
Perhaps the camera uses a separate circuit for audio clocking, and in one camera it has drift. This probably doesn’t help your situation, but it might accout for the phenomena.
I would suspect whichever camera is older as being the more likely culprit.
From this source: https://www.planetanalog.com/features/showArticle.jhtml;jsessionid=BDTAQENVJ3NVCQSNDLRCKHSCJUNN2JVN?articleID=196801770
Quartz crystals are shown to exhibit discontinuities in the frequency vs. temperature, or reactance vs. temperature characteristics of a crystal which may cause the frequency of the oscillation to shift or stop completely under a particular combination of temperature and voltage, in otherwise normally functioning units.
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David,
Have you tried recapturing the media to see if the problem happened during the capture?Lee Berger
http://www.leebergermedia.com
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