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7D onboard audio offset?

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Matt Lyon
7D onboard audio offset?
on May 24, 2011 at 8:43:27 pm

Hi all,

First post to this forum! (I usually stick w/ the Final Cut Pro one). I tried searching first, but apologies if this is already covered and I missed it.

I'm cutting a short that was shot on a 7D @ 23.976 fps. I've worked on some DSLR projects before, but this is the first one that used a clapboard. I'm noticing that the onboard audio (which we recorded as guide) is always one or two frames offset from picture.

I confirmed this is the case in both the camera original h264s and my converted ProRes files.

It's not a big deal, since I can sync our "good" audio manually, but this offset makes it tricky to use automated solutions like Pluraleyes.

Has anybody else seen this offset? Could it be a setting on the camera? (I wasn't the shooter in this case).

Thanks in advance,

Matt Lyon
Editor
Toronto


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Noah Kadner
Re: 7D onboard audio offset?
on May 25, 2011 at 2:44:06 pm

Yup- most DSLR onboard audio circuitry is pretty much terrible. Not surprised you are discovering an offset. Stick with the double system audio and be happy you were on a production wise enough to shoot with it.

Noah

Unlock the secrets of 24p, HD and Final Cut Studio with Call Box Training. Featuring the Panasonic GH2 and Canon 7D.


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Matt Lyon
Re: 7D onboard audio offset?
on May 25, 2011 at 11:30:12 pm

Thanks for the info Noah. This discovery has made me extra nervous, because I'm starting to hear people say things like, "we don't need to slate anymore, just use Pluraleyes!" (and that's not a dig at Pluraleyes - I think it's very useful software).

Matt Lyon
Editor
Toronto


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Noah Kadner
Re: 7D onboard audio offset?
on May 26, 2011 at 4:23:01 am

Slating's not just useful for sync, it also really helps keep you organized both in post and as you shoot. I just use an iPhone with MovieSlate- works like a charm and it's sometimes a lot simpler/more satisfying to manually sync.

http://www.pureblendsoftware.com/movieslate

Noah

Unlock the secrets of 24p, HD and Final Cut Studio with Call Box Training. Featuring the Panasonic GH2 and Canon 7D.


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Guy Smith
Re: 7D onboard audio offset?
on Jun 1, 2011 at 11:58:07 pm

Interestingly enough, I ran across this post after I did a little experiment converting m2t files (from HDV files created by my Z1U) using Cineform NeoScene and noted an offset of about 2 frames in the converted files (audio precedes the video). For the record, the audio on the original m2t files was in sync with the video.

I thought that I would try using NeoScene on the AVCHD files from my 7D and see what NeoScene would do with them, but noted that even before I did a conversion, there was already an offset on the captures direct from the 7D using the Canon EOS utility.

Bottom line is I guess I'm going to have to start using a clapboard on all my shoots! And I thought I'd solved my sync problems with Plural Eyes!


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Matt Lyon
Re: 7D onboard audio offset?
on Jun 2, 2011 at 1:54:08 pm

Thanks for the confirmation Guy. With the batch of 7D footage I'm currently working on, the offset seems to be almost always 2 frames, but every so often I'll see a clip that is only 1 frame off. AND the very rare occasion, a clip with be closer to three frames off (offset doesn't seem to always land cleanly on a "whole" frame!) This is frustrating because it would be much easier to deal with if the offset was at least consistent.

FWIW, I sent a request to Pluraleyes for a "manual sync offset" option.

Matt Lyon
Editor
Toronto


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