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Audio Drift Issue (47.962 khz & 29.96 fps???)
Hi everyone,
I captured some footage at DV50 through Final Cut Pro using Capture Now (because there were timecode breaks). I did two passes because the dailies tape has four channels of audio–I did one pass to capture channels 1 & 2 and one pass to capture channels 3 & 4, both with video.
In FCP, however, when I cut either or both clips into a sequence, the audio drifts very badly. I checked the original QT file (clip with channels 1 & 2) in my Capture Scratch and the audio drifts there, as well. So it’s definitely a capture problem. In the QT Inspector, it says the FPS is 29.96 and the audio is 47.962. Has anyone ever seen this before? This seems totally weird to me.
Here’s where it gets weirder: the clip where I captured channels 3 & 4 have an audio rate at 47.963, .001 higher than the other clip.
Any advice would be much appreciated!
Unfortunately, I don’t have the deck any longer, though acquiring it again probably won’t be a problem. I’m just trying to make sense of what’s going on!
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14 Replies
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[Richard Lowe] “Here’s where it gets weirder: the clip where I captured channels 3 & 4 have an audio rate at 47.963, .001 higher than the other clip. “
Some time back I also experienced that same strange audio sampling issue with a rented Panasonic deck. Every tape and every capture attempt reported a different sample rate in the 47.xxx range.
As I recall there was no easy solution for that one. It cost me days and days to sort out. I think we ended up having to use the camera on which the material was shot.
David Roth Weiss
Director/Editor
David Weiss Productions, Inc.
Los AngelesPOST-PRODUCTION WITHOUT THE USUAL INSANITY ™
A forum host of Creative COW’s Apple Final Cut Pro, Business & Marketing, Indie Film & Documentary, and Film History & Appreciations forums.
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Hi Dave,
The FCP Item Properties window shows 47962.4hz, which I imagine translates to 47.962 khz for the clip with channels 1 & 2 and 47.963.1hz for the clip with channels 3 & 4. (I am not an audio guy, unfortunately.)
However, the video says 29.97 in FCP.
Thanks!
–richard.
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David–
Thanks for the advice. Apologies that it took days and days, but thanks for giving me the heads up to not spend too much time on it.
It’s strange: we captured several tapes, but this is the only one with an issue. An anomaly or could it be a tape issue?
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What deck did you use?
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It was the AJ-SD93P Panasonic deck…
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And this was via firewire?
Are you absolutely sure the deck had the proper dif speeds and format changes for dv50?
What happens if you log and capture instead of capture now?
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How was the footage originated? Was it shot on a DV camera? It’s been a while, but I recall early generation consumer DV cameras had issues with audio drift due to some vagaries of the format. Didn’t the first gen XL-1 have issues with creating materials with strange audio sampling rates. At any rate, David Weiss’ advice is probably the surest fix: capture from the same camera that shot the material.
Matt Lyon
Editor
Toronto -
[Matt Lyon] “capture from the same camera that shot the material. “
Not in this case. If it’s an SDX900 (dv50), you aren’t going to use the $20,000 camera as a capture device. This isn’t a dv situation.
It’s all about the deck settings.
Jeremy
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Yeah, it was via Firewire.
I don’t know what the deck settings were. I didn’t set them, unfortunately, and I didn’t know it needed specific settings. The company we rented from didn’t mention it, either, when we told them we were capturing DV50.
So you’re feeling is it’s a deck setting? What should the AJ-SD930 be set to for DV50?
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[Richard Lowe] “So you’re feeling is it’s a deck setting?”
I am. Someone might have set it up for dv.
You’d have to dig through the manual and change the three or four places where you can choose dv vs dv50.
If all looks good, then Id’ run and log and cpature instead of capture now.
Also, you did only have one firewire device (the deck) connected to your Macs internal bus, correct?
Jeremy
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