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Home: Video University Forums: Mac Video:
audio off

efenugy
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Apr 10, 2006, 11:25 PM

Post #1 of 18 (2585 views)
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audio off	Can't Post

Why does my audio go off sync when recording mini dv tapes but not full size dv?

RatVega
Enthusiast

Apr 10, 2006, 11:33 PM

Post #2 of 18 (2582 views)
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Re: [efenugy] audio off [In reply to]	Can't Post

What is the length of the DV tape?

______________________________________________________________
Currently on a loaded 2.5GHz G5 dualie/5GB/1TB internal RAID/dual 19" monitors. Final Cut Studio, Adobe Suite, Boris RED. Shooting with Canon.

VU California Crew, Inland Empire Sub-Chapter (paragraph?)

efenugy
User

Apr 11, 2006, 12:21 AM

Post #3 of 18 (2578 views)
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Re: [RatVega] audio off [In reply to]	Can't Post

The full size dv tapes run 2-3 hours but no problem with those but the minis run about an hour.

Mike S
User

Apr 11, 2006, 5:41 AM

Post #4 of 18 (2573 views)
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Re: [efenugy] audio off [In reply to]	Can't Post

Make sure that you have the audio set to the same settings. If your camera is capturing 16bit audio make sure that your editing system is also set up for 16 bit audio
Mike S
V.P.
Ontario Professional Videographers Association
(www.opva.com)

efenugy
User

Apr 11, 2006, 10:54 AM

Post #5 of 18 (2570 views)
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Re: [Mike S] audio off [In reply to]	Can't Post

Thanks I'll check.

RatVega
Enthusiast

Apr 11, 2006, 3:47 PM

Post #6 of 18 (2551 views)
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Re: [efenugy] audio off [In reply to]	Can't Post

There is no technical reason that the audio should change. DVCAM and MiniDV only differ physically (the cases are larger, the tapes longer, and the coating is supposed to yield fewer drop-outs.) The output stream for both formats is the same, so quality could theorectically be slightly different but the sync should be the same.

Some people have posted problems with audio sync issues with long clips (hence my previous question about clip length.)

Make sure you have completely rendered the timeline and mixed down the audio before output. Some problems have inferred a RAM buffering/CPU speed issue with long clips, so if your machine is slower and or has limited RAM this may be an area to work with - shutting down unnecessary apps and freeing RAM (and CPU cycles) may improve results. There is also a possibility that the deck itself is the culprit; try another deck if you have one available.

______________________________________________________________
Currently on a loaded 2.5GHz G5 dualie/5GB/1TB internal RAID/dual 19" monitors. Final Cut Studio, Adobe Suite, Boris RED. Shooting with Canon.

VU California Crew, Inland Empire Sub-Chapter (paragraph?)

efenugy
User

Apr 11, 2006, 9:13 PM

Post #7 of 18 (2544 views)
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Re: [RatVega] audio off [In reply to]	Can't Post

My problem is in capture only.

efenugy
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Apr 11, 2006, 9:14 PM

Post #8 of 18 (2543 views)
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Re: [efenugy] audio off [In reply to]	Can't Post

I have two decks and it happens in both.

sky writer
Enthusiast

Apr 11, 2006, 10:50 PM

Post #9 of 18 (2534 views)
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Re: [efenugy] audio off [In reply to]	Can't Post

In Reply To

Why does my audio go off sync when recording mini dv tapes but not full size dv?

Are yo batch capturing or using Capture NOW? The reason I ask, is that I have had sync issues in the past when I used Capture Now, and didn't escape the capture before the end of timecode.

I have also had sync issues when there were slight dropouts during capture.

How much is it out of sync? Is it consistant, or does it drift, and get worse as the tape progresses?

RatVega
Enthusiast

Apr 12, 2006, 2:44 PM

Post #10 of 18 (2519 views)
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Re: [efenugy] audio off [In reply to]	Can't Post

Only on capture, same on both decks... Hmmmm.....

I think we have all had a capture problem from time to time, but this is odd...

Sky has it right about the Capture Now vs. Log and Capture (or Clip) mode, this has cause a few weird problems.

Let's see... first what I think we can eliminate:

It's not the Mac.
It's not the codec, you should be using the same one.
It's not FCP since it's just capturing what the codec gives it.
It's not the deck unless they both have the same oddity (really unlikely.)

This pretty much leaves:
Tape - there are some differences in the make-up of tapes, possibly more if you're using grade 1 DV and grade 9 mini-DV.
Mode of capture - I post footage for others and sometimes get some real crap. I had some recently in which the TC was so badly hammered I had to capture it in iMovie and convert it in order to get a usable clip. This is an area of suspicion because along with the presets there are also the capture window settings (in the tabs on the right side of the Capture window.)

Also as Sky asked, what is the nature of the sync? The possible causes for a static offset would be different from an increasing drift.

______________________________________________________________
Currently on a loaded 2.5GHz G5 dualie/5GB/1TB internal RAID/dual 19" monitors. Final Cut Studio, Adobe Suite, Boris RED. Shooting with Canon.

VU California Crew, Inland Empire Sub-Chapter (paragraph?)

efenugy
User

Apr 12, 2006, 9:02 PM

Post #11 of 18 (2507 views)
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Re: [sky writer] audio off [In reply to]	Can't Post

I capture in capture now but this only happens with the mini dv tapes.

efenugy
User

Apr 12, 2006, 9:03 PM

Post #12 of 18 (2506 views)
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Re: [RatVega] audio off [In reply to]	Can't Post

I use panasonic master quality tapes ,they are the best.

efenugy
User

Apr 12, 2006, 9:06 PM

Post #13 of 18 (2502 views)
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Re: [efenugy] audio off [In reply to]	Can't Post

It starts off in sync then later in the tape maybe half way it goes off. Once on the timeline I can grab the audio and shift to the left a few frames and its good from there on usually.

sky writer
Enthusiast

Apr 13, 2006, 10:27 AM

Post #14 of 18 (2473 views)
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Re: [efenugy] audio off [In reply to]	Can't Post

In Reply To

It starts off in sync then later in the tape maybe half way it goes off. Once on the timeline I can grab the audio and shift to the left a few frames and its good from there on usually.

Just so that I understand. It starts in sync, then "at some point" loses a few frames, then is consistantly out those few frames, right? It doesn't drift more and more as time goes on?

If that is the case, my money is on an audio dropout, probably caused by a video breakup (drop frame, etc.). If you can isolate where the sync change takes place (within a few seconds), zoom in on your audio waveform in the viewer. Scrub along and look for a flatline blank spot. It is obviously not going to be very big if it's only two frames, but if it is during a section with lots of amplitude, it should stick out. Then once you find it, take a look at the corresponding video track. See any pixelation, weirdness, anything?

If this doesn't work for you, then we'll keep trying.

sky writer
Enthusiast

Apr 15, 2006, 4:43 PM

Post #15 of 18 (2363 views)
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Re: [efenugy] audio off [In reply to]	Can't Post

How did you make out?

bbalser
User

Apr 16, 2006, 6:42 PM

Post #16 of 18 (2351 views)
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Re: [sky writer] audio off [In reply to]	Can't Post

What camera did you shoot with?
Did you double check the audio sample rate the camera is set for?

efenugy
User

Apr 19, 2006, 5:47 PM

Post #17 of 18 (2321 views)
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Re: [sky writer] audio off [In reply to]	Can't Post

I have checked the audio settings on the cameras and they are set correct. At first i thought that was the problem because they were off on my two vx 2000s but since then I have corrected that and it is still a problem.

bbalser
User

Apr 20, 2006, 9:27 PM

Post #18 of 18 (2302 views)
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Re: [efenugy] audio off [In reply to]	Can't Post

In your Browser in FCP, right click the clip, go to Item Properties. Check and verify the audio settings of the clip itself in the Browser.