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Losing Audio Sync over long clips…what causes that?
I have just done a project that involved the capturing of a 2 hour + 20 minute clip that I captured in one hit. I then noticed that every 20 minutes (approx) I had to cut the audio, move it to the right 2 frames and then stretch it back to keep it in sync with the video. I assume this means the audio was moving slightly faster than the video and I needed to slow it down…but why? Do I have something set wrong in FCP4.5. I appreciate any assistance you can give.
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7 Replies
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Sometimes losing audio sync is an indication that the capture rate isn’t set to the same rate as the source tapes, i.e. the source tape was recorded at 48Khz but the capture setting is 32Khz. Some cameras such as the Canon line don’t record audio at precisely 48Khz and 32Khz and sometimes that causes problems, even though FCP4.5 is supposed to know what camera is connected and make the appropriate adjustment. If you’re using a deck for capture and you’ve put in a Canon recorded tape, FCP may not know about the Canon audio, although I’m not sure about this since I’ve never tried to capture any of my Canon tapes from anything like a Sony DSR-11 deck.
In FCP version 1 I was always having sync issues with audio but since FCP 4X it became a non issue. Just make sure you’ve set your capture prefs to record just the first two channels, because if it’s set to anything other than that FCP will automatically drop the sample rate for capture down to 32Khz.
– Don
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Longest capture I’ve ever had to deal with was 90 minutes, and it worked perfectly, however it was DVCAM. Not mini DV…
The generous post made by Don is not quite on the mark however… if the audio was recorded at 12 bit, you need to change the capture preset to 32 kHz.. FCP doesn’t automatically recognize anything, and neither does any other NLE… but in your case, I don’t think this is the problem. Reason is the sync isn’t off far enough.
It’s much more likely that your disk drives dropped frames and THIS WILL cause an out of sync problem like you describe. Post more about your setup, what are the specs of your scratch disk, and what exactly was the source material on DV or DVCAM or?
Jerry
Apple Certified Trainer
Author: “Jerry Hofmann on Final Cut Pro 4” Click here
Dual 2 gig G5, AJA Kona SD, AJA Kona 2, Huge Systems Array UL3D
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[Jerry Hofmann] “Post more about your setup, what are the specs of your scratch disk, and what exactly was the source material on DV or DVCAM or? “
Knowing what camera it was shot on and what he used to capture from would also help…
Mitch Ives
Insight Productions Corp.
mitch@insightproductions.com
http://www.insightproductions.com -
You’re quite right, Gerry. I forgot about mentioning the 12/16 bit thing. Inexcusable on my part. I stand dejected (corrected). However, what I was referring to about FCP changing bit/sample rate for me is when I choose to download the 2nd two audio channels from a tape recorded with a Canon. In the advanced audio prefs when I make the change to get channels 3 & 4 I’ve noticed that FCP will change the bit rate from 16 to 12 without any further prompting (using FCP4.5).
– Don
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Thanks Jerry. My setup is an iMac G4 with FCP 4.5 and the scratch disc is a 200GB Firewire external drive connected via a firewire cable. The source footage came from DVCAM tape and not MiniDV. Thanks.
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I don’t know what it was shot on, but I do know that I used my Sony DSR-250P camera to capture from. Thanks.
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Wanted to chime in w/ a semi-related experience I had earlier today. I captured five or six minutes of old vhs footage (recorded from vhs deck to mini dv and then captured from mini dv) into fcp5 and my audio was 26 frames off – had to move my audio ahead of my video to achieve “lip lock.” I didn’t check my capture settings prior to any of this so I can’t diagnose what happened. It was easy enough to fix but a curious situation….
Anyway, Happy Weekend folks.
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