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Will I have SYNCING PROBLEMS when I record video with a separate recorded audio mix?

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sally obrien
Will I have SYNCING PROBLEMS when I record video with a separate recorded audio mix?
on Aug 24, 2009 at 1:36:58 pm

I'm going to film someone singing in a recording studio today. Later, they're going to give me the mixed track so I can sync it up to my video.

I've heard of cases where the video and audio can go out of sync; like one has a delay over the other. Is this something that's avoidable depending on how you record it? Do we need to set our cameras or audio recorders to a certain setting to make sure this doesn't happen?

Or is this always inevitable, and you just have to fix it in post-production? If so, what's the best way to do that?


Sal


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Thax Clave
Re: Will I have SYNCING PROBLEMS when I record video with a separate recorded audio mix?
on Aug 24, 2009 at 6:33:32 pm

If you are shooting digital video, and they are recording the audio digitally, they sync should be perfect.

(Unless the recording studio changes the "speed" of the recording for some reason.)



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Ty Ford
Re: Will I have SYNCING PROBLEMS when I record video with a separate recorded audio mix?
on Aug 24, 2009 at 7:48:21 pm

Hello Sally and welcome to the Cow Audio Forum.

My experiences vary from those of Thax.

I have had everything from, "works fine even with a sample rate convert" to "no way this will work."

The conventional wisdom dictates that an audio recorder with SMPTE time code be slaved to the camera's timecode output.

My successful experiences have not always required time code. The best advice I can offer is to try the specific gear you intend to use, using 48 kHz as the audio sample rate on the recorder and see what happens. It sometimes takes minutes for sync to creep; sometimes sync will only be off a few frames after an hour. Please do let us know what you find.

Regards,

Ty Ford

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






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Sam Mallery
Re: Will I have SYNCING PROBLEMS when I record video with a separate recorded audio mix?
on Aug 24, 2009 at 10:02:59 pm

If there is a lot of video shot, and a lot of audio recorded in the studio, the biggest problem will likely be figuring out what audio belongs with what video. Once you figure out what audio belongs with what video, you have to line them up manually in the timeline so it looks natural.

Once you have the audio and video lined up, you have to keep an eye out for drift. No matter if both recordings are done digitally, the audio and video can still drift. Basically, you will notice that if you have everything lined up properly, after a while you may notice that the audio and video are no longer synced. It starts to look like a poorly dubbed Kung Fu movie. You just have to go back on the timeline and figure out where the audio and video start to drift. When you find that point, you have to make a cut in the audio and move it maually so that it's in sync again.



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John Livings
Re: Will I have SYNCING PROBLEMS when I record video with a separate recorded audio mix?
on Aug 25, 2009 at 3:07:28 pm

Hi Sal,

This post might be to late for you , but here goes...

I would agree that that things may drift out of sync.

My first choice would be to "Pull" the sound off the Main mixer, Meaning use the Tape Out to your recorder.

Also if you can record to your Camera using a longer cable and a boom pole for your Mic, That would be a good thing. This could turn out to be your best Audio recording.

It's actually kind of simple to match up Video and Audio if you can do the following; (This also works real well for Multi- Camera Shoots if you have time code breaks) W/O TC breaks use FCP Multi cam filter.

1. Start Video and Audio a couple of minutes before anything happens, About a minute before the action starts use a clapboard or hand clap that is IN-FOCUS and is picked up by the audio recorder.

2. Record Video and Audio... Action stops, wait a minute or so with the camera and audio running, And use the clapboard again the same as before. And if you can, Don't start and stop cameras or recorders during the shoot. (No time code breaks)

This makes it a little easier it to match things up in post.

Many reasons to be out of Sync, I will List a few.--- 1. DF vs. NDF settings on cameras, recorders and your NLE system settings---Digital tape---Tape transporters---Etc.

Also Lock the Video track and edit the audio track, One of the reasons is that in FCP you can only move the video 1 Frame and the audio 1/100 of a Frame.( Or something like that)

Good Luck







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Thax Clave
Re: Will I have SYNCING PROBLEMS when I record video with a separate recorded audio mix?
on Aug 25, 2009 at 11:23:07 pm

[John Livings] "DF vs. NDF settings"

TC settings have no affect on speed or timing.
TC is simply a frame-numbering system.

I have shot recording studio footage many times over the years.
Then manually connected audio and video footage.
I shoot recording sessions and build documentations of the sessions.

Each of the units (video camcorder and digital recording system) are each locked internally to their own dead-on-accurate "clocks."
There should be no reason that a digital camcorder running at standard speed would slip even one frame in regard to a digital audio recording.
(UNLESS, again, the recording engineer intentionally "adjusts" the length of the recording for some reason.)

I've imported audio from digital sources (a CD or MD of the finished audio product works great) and
had zero "slippage" in straight 55 minute video takes.




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John Livings
Re: Will I have SYNCING PROBLEMS when I record video with a separate recorded audio mix?
on Aug 26, 2009 at 5:10:47 am

Hi Thax,

Please take a look this.

http://forums.creativecow.net/thread/30/854719#854729

Also if you Google "df vs. ndf" you will get the bottom line, And that is in about 1 hour the time codes will differ about 4 seconds (The actual amount of frames will be the same if the only difference is DF vs. NDF)

I agree, Some projects require no syncing, they match up, Others don't.

I may be incorrect on this.

John



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Ty Ford
Re: Will I have SYNCING PROBLEMS when I record video with a separate recorded audio mix?
on Aug 26, 2009 at 6:09:06 am

John,

Suffice it to say that Thax has been very lucky/successful with this and some (myself included) have seen it go either way. I've seen enough posts on forums where people are asking why the very thing she's asking about didn't work to give her a green light.

I think the important thing here is not to get into a can/can't argument, but to let Sally know that she isn't guaranteed success and that she should test first.

Regards,

Ty Ford




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






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Thax Clave
Re: Will I have SYNCING PROBLEMS when I record video with a separate recorded audio mix?
on Aug 26, 2009 at 11:03:59 am

[John Livings] "Also if you Google "df vs. ndf" you will get the bottom line, And that is in about 1 hour the time codes will differ about 4 seconds (The actual amount of frames will be the same if the only difference is DF vs. NDF)
"


Yes, the time CODES differ (that's why there are 2 systems,)
but the LENGTH does not change.

TC is just a numbering system.
It counts and identifies frames.
It does not affect length or speed.






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