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What causes out of sync? using dslr and h4n zoom

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Grant Wilber
What causes out of sync? using dslr and h4n zoom
on Oct 19, 2012 at 11:18:57 pm

So I used my Canon T2i and a H4n Zoom to record some interviews and its going out of sync every minute. I've recorded for a year with this set up and have never ran into this problem including recording presentations for hours.

What settings or reasons would cause this set up to be out of sync?


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Peter Groom
Re: What causes out of sync? using dslr and h4n zoom
on Oct 20, 2012 at 8:49:17 am

Probably different sample rates.
One is prob on 44.1 khz and the other on 48khz. Chexk the recording menus of each.
Peter

Post Production Dubbing Mixer


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Grant Wilber
Re: What causes out of sync? using dslr and h4n zoom
on Oct 20, 2012 at 10:53:53 am

Both of them are 48.0 KHz.

I thought it might be because I was trying to keep it in H264 when I usually convert to prores. But I just converted and there is still an issue with it.

ALTHOUGH: I dug into the audio info and noticed it has 'TC rate' set to 25. I'm gonna assume thats the issue. I had no clue my zoom could even be switched to different rates or even how it possibly could've of done that.

I'm looking for ways to convert 25 audio to 23.978 footage but not coming up with anything yet. Any suggestions?


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igor jovcevski
Re: What causes out of sync? using dslr and h4n zoom
on Oct 20, 2012 at 2:51:39 pm

audio has no specific fps actually, it is 48000 fps in your case to be precise. The drift is mainly caused by the accuracy of the quarz clock in recorders. secondly, it may be related to codecs and audio duration change.the fps you find in your wav file is actually metadata only. you can easily just import it in Audacity and export whatever you like without any metadata.It's normal go off few frames for 20 min footage. you can avoid this by having shorter recordings.

Igor
Woowave.com
tools for digital artists


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Brian Reynolds
Re: What causes out of sync? using dslr and h4n zoom
on Oct 20, 2012 at 10:48:16 am

A colleague of mine had a similar problem recently and currently working through it with testing, here is a copy of an email with some more info.
Yes Im aware this problem occurred on a Cannon 5D3

Direct from the operation manual there are two ways of recording moving vision on the 5D3. As mentioned over the phone I always send the camera out in ALL-I mode, but I did noticed (camera person) had selected the compressed mode, IPB mode. As the camera is new I’m learning too. I will look in the blogs to see if anyone else has had similar issues.

Here you’ll see the options:




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Andrew Rendell
Re: What causes out of sync? using dslr and h4n zoom
on Oct 20, 2012 at 11:17:16 am

What software are you using to sync the audio with the video?

There's a long standing issue with FCP that it assigns a "frames per second" speed to audio and if you haven't got the settings right when you import it will, for example, slow down an audio track with an assignment of 25fps to match video at 24fps when you need it to not do that.


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Grant Wilber
Re: What causes out of sync? using dslr and h4n zoom
on Oct 20, 2012 at 11:24:05 am

I'm cutting on FCP7 and was syncing with Pluraleyes.

I don't think the TC rate thing I found is an issue because I looked back on older projects and some the audio TC is 23.98 and some its 25 and this is the first time I experienced audio out of sync.

Andrew, maybe FCP is changing the audio rate. How do I go about checking that this isn't done?


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Grant Wilber
Re: What causes out of sync? using dslr and h4n zoom
on Oct 20, 2012 at 11:29:54 am

It looks like after an hour its off by 3 seconds 16 frames


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Grant Wilber
RE: What causes out of sync? using dslr and h4n zoom
on Oct 20, 2012 at 12:50:53 pm

So I think its solved for at least now.
Found this thread: http://forums.creativecow.net/thread/8/1155930

I changed the audio speed to 100.09% and everything synced up fine.

Have no clue why this all of a sudden happen after a year and a half of never receiving this problem with this same set up. My zoom is funky from time to time and I have had to factory restart it so maybe it's an issue with that?


EDIT:

actually it's still doing it. This is totally weird. The speed change synced up an hour and a half presentation, but having trouble on a 5 minute clip.


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John Fishback
Re: RE: What causes out of sync? using dslr and h4n zoom
on Oct 29, 2012 at 10:47:02 pm

FCP assumes a frame rate from the Easy Setup used at the start of your project. Try this advice from Jeremy Garchow, "First, delete the audio out of FCP and your timeline. Set FCP up in an easy setup for your project (23.98 , 25 ,etc.), then quit FCP. Now reopen FCP and reimport your audio." This has worked for others and often is easier than pulling the audio up or down.

John

MacPro 8-core 2.8GHz, 8 GB RAM, OS 10.7.4, QT10.1, Kona 3, Dual Cinema 23, ATI Radeon HD 5870, 24" TV-Logic Monitor, ATTO ExpressSAS R380 RAID Adapter, PDE enclosure with 8-drive 6TB RAID 5
FCS 3 (FCP 7.0.3, Motion 4.0.3, Comp 3.5.3, DVDSP 4.2.2, Color 1.5.3)
FCP-X 10.0.5

Pro Tools HD w SYNC IO & 192 Digital I/O, Yamaha DM1000, Millennia Media HV-3C, Neumann U87, Schoeps Mk41 mics, Genelec DSP Monitors, Prima CDQ120 ISDN


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Peter Groom
Re: What causes out of sync? using dslr and h4n zoom
on Oct 20, 2012 at 1:11:39 pm

The audio adjustment is called a Pull up and is to sync different frame rates. FCP is a donkey for this type of trick.
Id check that the sqequence settings match that of the audio and video. I wouldnt be surprised if the video and the sequence settings differ. zoom has no adjustment for frame rate, only bit depth and sample rate. I even think fcpmight have different settings on project, sequences and timeline settings. That is why i use avid (amongst dozens of other reasons.)
Peter

Post Production Dubbing Mixer


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Ty Ford
Re: What causes out of sync? using dslr and h4n zoom
on Oct 21, 2012 at 2:14:58 pm

Hello Grant and welcome to the Cow Audio Forum.

Thanks so much for bringing this issue to the Cow and letting us thrash it out with you.

That you were able to have sync for that long with your set up, I find unusual, damn lucky and good for you!

What's changed? I like the idea that an unintended menu flip did it. Can you reset the camera to it's original settings? (noting the customs you have made, so you can get back to them.)

Could also be that, over time, the values of the circuitry of your two clocks have shifted a little.

Please do keep us in the loop as you discovery continues.

Regards,

Ty Ford
Cow Audio Forum Leader


Want better production audio?: Ty Ford's Audio Bootcamp Field Guide
Ty Ford Blog: Ty Ford's Blog


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